JP5805246B2 - Vehicle power supply - Google Patents

Description

  The present invention relates to a vehicle power supply apparatus having an inverter that converts a DC input voltage into an AC output voltage, and a converter that converts the DC input voltage into a DC output voltage.

A vehicle using electric energy such as a hybrid vehicle includes a drive motor, a high voltage battery for supplying power to the drive motor, and an inverter. The voltage of the high voltage battery generally reaches 100V to 400V, the inverter converts the DC voltage of the high voltage battery into an AC voltage, and supplies power to the drive motor.
In addition, in conventional vehicles, power is supplied to 12V electric devices by an alternator that generates power using engine power. However, since hybrid vehicles have a mode in which the engine stops, the voltage of the high voltage battery is set to 12V voltage. A converter for converting to 12V is mounted, and power is supplied to the 12V electric equipment by the converter.
The inverter and converter can be mounted on the vehicle in various ways, such as a configuration in which the inverter and the converter are each mounted in separate housings, and a configuration in which the inverter and the converter are mounted in the same housing. Form is taken.

A large-capacity smoothing capacitor is provided between terminals on the input side of the inverter in order to smooth voltage fluctuations and stabilize the operation of the inverter. In consideration of driver rescue work in the event of an accident and vehicle maintenance at a vehicle maintenance shop, it is necessary to discharge the electric charge charged in this smoothing capacitor as soon as possible, but the conventional discharge circuit provided for this discharge is The capacitor was discharged by converting the electric charge into heat with a large-capacity resistor (see Patent Document 1).
Throwing away the charge of a large-capacity capacitor as heat is not only a waste of power, but if you try to reduce the cost of the discharge circuit by avoiding heat generation of the resistor, the discharge time will be longer, and conversely if you try to shorten the discharge time There is a problem that the capacity of the resistor needs to be increased and the cost of the discharge circuit increases.

  As means for solving this problem, an inverter that converts the DC power of the main battery into AC power and drives the traveling motor, a smoothing capacitor connected in parallel to the inverter, charging and discharging of the capacitor, and an inverter are provided. In a control device for an electric vehicle, comprising: a control means for controlling; a sub-battery for supplying power to the control means; and a DC / DC converter for lowering the voltage of the main battery to charge the sub-battery. The control means that should effectively use the electric charge for charging the sub-battery at the time of discharging supplies the electric charge to the sub-battery via the DC / DC converter when the capacitor is discharged (see Patent Document 2).

  According to Patent Document 2, when the electric vehicle stops running and the capacitor charge is discharged, the control means supplies the capacitor charge to the sub-battery via the DC / DC converter. The discharge circuit does not waste energy as heat and can be used effectively for charging the sub-battery. Further, since the discharge circuit is not necessary, not only the cost is reduced, but also the discharge can be completed in a short time without considering the heat radiation of the discharge circuit.

JP-A-8-33103 JP 10-248263 A

The means for discharging the electric charge of the smoothing capacitor using the DC / DC converter described in Patent Document 2 is effective in that an extra discharge circuit may not be required. However, in general, in hybrid vehicles and electric vehicles, a target value for the discharge time is commonly determined regardless of the capacity of the mounted smoothing capacitor, and the DC / DC converter is a voltage conversion circuit. However, the current flowing through this, that is, the discharge current cannot be controlled.
In general, the discharge current depends on the operating conditions of the auxiliary equipment of the vehicle. Therefore, there is a problem that the discharge of the capacitor charge cannot be completed within a target discharge time in a specific vehicle type in which a large-capacity smoothing capacitor is mounted only by the means described in the invention of Patent Document 2.

As a result, in order to achieve the target discharge time, an additional discharge circuit other than the DC / DC converter is required, and the effect of reducing the cost by eliminating the need for an extra discharge circuit, which is the original purpose, is maximized. There are problems that cannot be realized.
In addition, the means described in Patent Document 2 has a first object to effectively use the electric charge of the capacitor for charging the sub-battery, instead of wasting the electric charge of the capacitor as heat. However, the state of the sub-battery is not known at the time of the accident, and in some cases, liquid leakage or the like may occur due to destruction of the battery case, and it is not always safe to charge it.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vehicle power supply device for achieving a target discharge time and minimizing the cost required for a discharge circuit. It is what.

A power supply device for a vehicle according to the present invention includes an inverter device that drives a motor by converting DC power of a main battery to AC power, a smoothing capacitor connected in parallel to the inverter device, charge / discharge of the capacitor, and an inverter DC having an inverter control means for controlling the device, a sub-battery for supplying power to the inverter control means, and a power conversion switching element mounted inside, and charging the sub-battery by lowering the voltage of the main battery DC / DC converter and DC / DC converter control means for converting power by selectively or steplessly controlling the drive frequency of the switching element of the DC / DC converter, and the inverter control means is configured to charge the capacitor when discharging the capacitor. Supply to sub-battery or equipment connected to it via DC / DC converter And controlled so, the DC / DC converter control means have a conversion efficiency deterioration means DC / DC converter loss is controlled to be better at the time of discharging operation of the capacitor than in normal operation is increased, the conversion efficiency deteriorates means The switching frequency is controlled so as to increase the switching loss by increasing the driving frequency of the switching element .

The vehicle power supply device according to the present invention includes an inverter device for driving a motor by converting DC power of a main battery into AC power, a smoothing capacitor connected in parallel to the inverter device, and charging / discharging of the capacitor. And an inverter control means for controlling the inverter device, a sub battery for supplying power to the inverter control means, a DC / DC converter for charging the sub battery by dropping the voltage of the main battery, and power conversion of the DC / DC converter DC / DC converter control means for controlling the power supply, and the inverter control means controls to supply the electric charge to the sub-battery or a device connected thereto via the DC / DC converter when the capacitor is discharged. In the DC converter control means, the output voltage of the DC / DC converter becomes a desired target value. Controls to have an output voltage regulating means for controlling the output voltage during discharge of the capacitor is set higher than the target value, the output voltage adjusting means, before and after the inverter control means to discharge the capacitor, DC The target output voltage is set so that the change in the output voltage of the / DC converter becomes small .

According to the present invention, since the loss of the DC / DC converter is larger during the capacitor discharging operation than during the normal operation, the discharging time can be shortened compared to the conventional case, and the capacitor charge can be discharged within the target discharging time. Can be completed. Further, no additional discharge circuit other than the DC / DC converter is required, and the cost of the discharge circuit can be minimized.
Further, according to another invention, the output voltage of the DC / DC converter increases, and the current flowing through the sub-battery and the device connected to the sub-battery increases, so that the discharge time can be shortened compared to the conventional case, and the target discharge time The discharge of the capacitor charge can be completed within. Further, no additional discharge circuit other than the DC / DC converter is required, and the cost of the discharge circuit can be minimized.

BRIEF DESCRIPTION OF THE DRAWINGS It is a whole block diagram of the vehicle power supply device concerning Embodiment 1 of this invention. It is a circuit diagram of the DC / DC converter used for Embodiment 1 of this invention. It is a figure which shows the flowchart of the conversion efficiency deterioration control in the vehicle power supply device of Embodiment 1 of this invention. It is a whole block diagram of the vehicle power supply device concerning Embodiment 2 of this invention. It is a figure which shows the flowchart of the output voltage adjustment control in the vehicle power supply device of Embodiment 2 of this invention. It is a figure which shows the flowchart of conversion efficiency deterioration control in the vehicle power supply device of Embodiment 3 of this invention. It is a figure which shows the data table of the conversion efficiency deterioration control in the vehicle power supply device of Embodiment 3 of this invention. It is a figure which shows the data table of the conversion efficiency deterioration control in the vehicle power supply device of Embodiment 3 of this invention. It is a figure which shows the data table of the voltage output adjustment control in the vehicle power supply device of Embodiment 3 of this invention. It is a figure which shows the flowchart of the control method in the vehicle power supply device of Embodiment 4 of this invention. It is a figure which shows the flowchart of the control method in the vehicle power supply device of Embodiment 5 of this invention. It is a figure which shows the flowchart of the control method in the vehicle power supply device of Embodiment 6 of this invention.

Embodiment 1 FIG.
A vehicle power supply device according to Embodiment 1 of the present invention will be described below with reference to FIGS.
FIG. 1 shows a vehicle power supply device including at least an inverter that converts a DC input voltage into an AC output voltage and a converter that converts the DC input voltage into a DC output voltage, and is used for a hybrid vehicle and an electric vehicle. It is suitable as a power supply device for a traveling motor.

In FIG. 1, a motor 202 for a running motor is a power running / regenerative motor, and for example, a permanent magnet type AC synchronous motor is used. The electric motor 202 is driven and controlled by the inverter device 203, and converts power supplied to the electric motor 202 from direct current to alternating current during power running, and converts the regenerative power of the electric motor 202 from alternating current to direct current during regeneration.
A smoothing capacitor 204 attached to the inverter device 203 is connected in parallel, and the capacitor 204 is connected to a main battery 205 that can be charged and discharged. The main battery 205 is composed of, for example, a lithium ion battery or a nickel metal hydride battery.

  A sub battery 206 is connected to the main battery 205 via the DC / DC converter 100, and the DC / DC converter 100 converts the DC input voltage from the main battery 205 into a DC output voltage to charge the sub battery 206. The sub battery 206 has a lower voltage than the main battery 205 and can be charged and discharged. The direct current output from the sub-battery 206 is supplied to various control units (such as an inverter control device 208 and a DC / DC converter control device 209 described later) and a load 207 of an auxiliary machine group of the vehicle such as an electric power steering device.

  An inverter control device 208 that controls the inverter device 203 and controls charging / discharging of the smoothing capacitor 204 is connected to the inverter device 203. The DC / DC converter 100 is connected to a DC / DC converter control device 209 that operates based on an instruction from the inverter control device 208 and drives and controls the DC / DC converter 100. The DC / DC converter control device 209 includes conversion efficiency deterioration means 210 that controls the loss of the DC / DC converter 100 so that it is greater during the discharging operation of the capacitor 204 than during normal operation. The conversion efficiency deterioration means 210 will be described later in detail with reference to FIG.

  FIG. 2 shows a specific circuit configuration diagram of the DC / DC converter 100. The transformer 104 that changes the voltage according to the turn ratio of the primary winding 111 and the secondary windings 112 and 113, and the DC / DC converter In order to supply DC power to 100, input terminals 101a and 101b (collectively input terminal 101) connected to main battery 205 and a plurality of switching elements 12a to 12d for power conversion (collectively switching elements 12) are provided. The inverter circuit 103 that switches the DC power supplied from the input terminal 101 and supplies the pulse wave power to the primary winding 111 of the transformer 104, and a plurality of rectifier elements 105 and 106, and the secondary of the transformer 104 A rectifier circuit 107 that rectifies AC power transmitted to the windings 112 and 113, and an output terminal 110 that outputs DC power. 110b (collectively the output terminal 110), the choke coil 108 connected between the center tap portion 114 of the transformer 104 and the output terminal 110a and smoothing the AC power rectified by the rectifier circuit 107, and both output terminals 110 This is a so-called insulation type DC / DC converter including a smoothing capacitor 109 that is connected between them and smoothes the AC voltage rectified by the rectifier circuit 107.

The DC / DC converter control device 209 has an internal temperature from the DC / DC converter 100, specifically, the temperature of magnetic components such as the switching element 12, the rectifier circuit 107, the transformer 104 and the choke coil 108, and the DC / DC converter. The current flowing through 100 is input and monitored, and the DC / DC converter 100 is activated or deactivated.
In the vehicle power supply device of FIG. 1, the inverter control device 208 controls the inverter device 203 to convert the DC power of the main battery 205 into AC power and drive the motor 202. Further, the inverter control device 208 controls charging / discharging of the capacitor 204, and controls to supply electric charge to the sub battery 206 or a device (load 207) connected thereto via the DC / DC converter 100 at the time of discharging. The DC / DC converter control device 209 performs control so that the output voltage of the DC / DC converter 100 becomes a desired target value.

Next, the control method of the vehicle power supply device of the present invention will be described with reference to the flowchart shown in FIG. FIG. 3 shows a flowchart when the conversion efficiency deterioration means 210 of the DC / DC converter controller 209 controls the conversion efficiency deterioration of the DC / DC converter 100. This flowchart is repeatedly executed at a predetermined cycle, for example, a 10 ms cycle. Is.
In FIG. 3, step 301 confirms whether the instruction from the inverter control device 208 is a discharge sequence of the capacitor 204. In step 302, if it is determined in step 301 that the discharge sequence is (Y), the drive frequency f of the switching element 12 of the DC / DC converter 100 is set to a value xf1 larger than the set value xfn when not in the discharge sequence.

If it is determined in step 301 that the discharge sequence is not (N), the process proceeds to step 303 where the drive frequency f of the switching element 12 of the DC / DC converter 100 is set to the set value xfn. This set value xfn is a value that optimizes the power conversion of the DC / DC converter 100, and is ideally set to have the highest efficiency that can be realized by the converter.
Step 304 drives and controls the switching element 12 of the DC / DC converter 100 based on at least the value of the driving frequency f.

  According to the first embodiment, the DC / DC converter 100 controls the drive by setting the drive frequency f to a larger value during the discharge sequence than when it is not the discharge sequence of the capacitor 204 (during normal operation). The switching loss of the DC / DC converter 100 is larger in the discharge sequence than in the non-discharge sequence (during normal operation). As a result, since the discharge time of the capacitor 204 can be shortened compared to the conventional case, the discharge of the capacitor 204 is completed within the target discharge time. Further, an additional discharge circuit other than the DC / DC converter 100 is not required, and the cost of the discharge circuit can be minimized.

  In the above description, the driving control is performed so that the switching loss is increased by setting the driving frequency f to a larger value in the discharging sequence than in the discharging sequence of the capacitor 204 (during normal operation). However, the same effect can be obtained by setting the drive frequency f to a small value and controlling the drive so that the iron loss of the transformer 104 is increased. Whether the driving frequency should be increased to increase the switching loss or the driving frequency should be decreased to increase the iron loss in order to deteriorate the overall loss of the DC / DC converter 100 depends on the characteristics of the DC / DC converter 100.

In the above description, two values to be set for the drive frequency f are provided, and control is selectively used when the discharge sequence is not used and when the discharge sequence is not used. A circuit for switching the inclination may be provided, and this may be used separately during the discharge sequence and when not in the discharge sequence.
Specifically, a circuit with a large change per time is used when not in the discharge sequence (during normal operation), and a circuit with a small change per time is used during the discharge sequence.
In this way, the DC / DC converter 100 has a smaller change slope of the rise and fall of the switching element 12 during the discharge sequence than when it is not the discharge sequence of the capacitor 204 (during normal operation). The loss of the DC / DC converter 100 is greater in the discharge sequence than in the discharge sequence (during normal operation). As a result, since the discharge time of the capacitor 204 can be shortened compared to the conventional case, the discharge of the capacitor 204 is completed within the target discharge time. Further, an additional discharge circuit other than the DC / DC converter 100 is not required, and the cost of the discharge circuit can be minimized.

Further, in FIG. 2, the rectifier circuit 107 is illustrated as a diode, but the transformer 1 is used as a means for deteriorating the overall loss of the DC / DC converter 100 by using the rectifier circuit 107 as a synchronous rectifier type using the MOSFET as a switching element. The dead time between the switching element on the secondary side and the switching element on the secondary side of the transformer may be switched between the discharge sequence and the non-discharge sequence.
Specifically, in the discharge sequence, zero volt switching is not established more than in the non-discharge sequence (during normal operation) (when the dead time of the primary-side switching element is increased compared to during normal operation). If the secondary dead time is synchronized with the primary timing), the loss of the DC / DC converter is larger during the capacitor discharging operation than during the normal operation, so the discharging time is longer than the conventional one. The discharge of the capacitor charge is completed within the target discharge time. Further, no additional discharge circuit other than the DC / DC converter is required, and the cost of the discharge circuit can be minimized.

Further, similarly to the above, the rectifier circuit 107 of FIG. 2 is set as a synchronous rectification type, and as means for deteriorating the overall loss of the DC / DC converter 100, the transformer primary side switching element and the transformer secondary side switching element 12 The drive timing may be switched between the discharge sequence and the non-discharge sequence.
Specifically, in the discharge sequence, if the drive timing of the secondary side switching element is delayed with respect to the drive timing of the primary side switching element, compared to the case where it is not the discharge sequence (during normal operation), DC The loss of the / DC converter is larger during the capacitor discharging operation than during the normal operation, so that the discharging time can be shortened compared to the conventional case, and the discharging of the capacitor charge is completed within the target discharging time. Further, no additional discharge circuit other than the DC / DC converter is required, and the cost of the discharge circuit can be minimized.

  In the first embodiment, the switching driving frequency is selected by two options. However, for example, the switching driving frequency is set in a plurality of steps or steplessly according to the detected current flowing through the DC / DC converter 100. You may make it change to. Similarly, the slope of the rise and fall of the voltage across the switching element 12, the dead time, and the drive timing may be changed in a plurality of steps or steplessly according to the current.

  In the first embodiment, a plurality of means for deteriorating the loss of the DC / DC converter 100 have been described. However, any other method may be used as long as it is a means for deteriorating the loss. Even if it is not an isolated converter, the same thing can be done with a non-insulated converter, that is, switching loss and loss of magnetic parts can be deteriorated.

Embodiment 2. FIG.
Next, a vehicle power supply device according to Embodiment 2 of the present invention will be described with reference to FIGS.
FIG. 4 shows a vehicular power supply apparatus including an inverter device 203 that converts a DC input voltage into an AC output voltage and a DC / DC converter 100 that converts the DC input voltage into a DC output voltage. In the first embodiment, the DC / DC converter control device 209 has the conversion efficiency worsening means 210. However, in the invention of the second embodiment, instead of the conversion efficiency worsening means 210, the output voltage is changed from the target value when the capacitor 204 is discharged. The output voltage adjusting means 211 is set to be controlled to be higher. Other configurations are the same as those in FIG. 1 of the first embodiment, and the same or corresponding parts are denoted by the same reference numerals and description thereof is omitted.

Next, the control method for the vehicle power supply device of the present invention will be described with reference to the flowchart shown in FIG. FIG. 5 shows a flowchart when the output voltage adjusting means 211 of the DC / DC converter control device 209 performs output voltage adjustment control of the DC / DC converter 100. This flowchart is repeatedly executed at a predetermined cycle, for example, a 10 ms cycle. Is.
In FIG. 5, step 401 confirms whether or not the instruction from the inverter control device 208 is a discharge sequence of the capacitor 204. If it is determined in step 401 that the discharge sequence is (Y), step 402 sets the target output voltage V of the DC / DC converter 100 to a value xV1 that is larger than the set value xVn when not in the discharge sequence.

If it is determined in step 401 that the discharge sequence is not (N), the process proceeds to step 403, where the target output voltage V of the DC / DC converter 100 is set to the set value xVn. This xVn is an optimal value for charging the sub-battery 206 in a healthy and continuous manner, and is ideally set so as to minimize the deterioration of the battery life while the sub-battery 206 is almost fully charged. is there.
Step 404 drives and controls the switching element 12 of the DC / DC converter 100 based on at least the value of the target output voltage V.

  According to the second embodiment, the DC / DC converter 100 controls the drive by setting the target output voltage V to a larger value during the discharge sequence than during the discharge sequence of the capacitor 204 (during normal operation). Therefore, the electric power supplied from the DC / DC converter 100 to the load 207 of the auxiliary machinery group of the vehicle such as the sub-battery 206 and various control units and the electric power steering device increases. As a result, since the discharge time of the capacitor 204 can be shortened compared to the conventional case, the discharge of the capacitor 204 is completed within the target discharge time. Further, an additional discharge circuit other than the DC / DC converter 100 is not required, and the cost of the discharge circuit can be minimized.

In the above description, two values to be set for the target output voltage V are provided, and control is selectively used during the discharge sequence and when it is not the discharge sequence. However, for the purpose of reducing the stress applied to the battery, the capacitor The target output voltage may be set so that the change in the output voltage of the DC / DC converter 100 is small before and after the discharge 204 is performed. Thereby, in addition to the effect according to the second embodiment, the electric charge of the capacitor 204 can be discharged while minimizing the stress applied to the sub battery 206, so that the effect of extending the life of the sub battery 206 can be obtained. it can.
In the second embodiment, the target output voltage is selected by two options. For example, the target output voltage is changed in a plurality of steps or steplessly according to the detected current flowing through the DC / DC converter 100. It doesn't matter if you do.

Embodiment 3 FIG.
Next, a vehicle power supply device according to Embodiment 3 of the present invention will be described with reference to FIGS.
In the vehicular power supply device according to the third embodiment, the DC / DC converter control device 209 includes both the conversion efficiency deterioration means 210 shown in the first embodiment and the output voltage adjustment means 211 shown in the second embodiment. Further, it has measuring means for measuring the output current of the DC / DC converter 100 and measuring means for measuring the temperature of the switching element 12, and the other configurations are the same as those in FIGS. 1 and 4 of the first and second embodiments. The illustration is omitted.

Next, the control method of the vehicle power supply device of the present invention will be described with reference to the flowchart shown in FIG. FIG. 6 shows a flowchart when the conversion efficiency deterioration means 210 and the output voltage adjustment means 211 of the DC / DC converter control device 209 perform the conversion efficiency deterioration control and the output voltage adjustment control of the DC / DC converter 100. Are repeatedly executed in a predetermined cycle, for example, a 10 ms cycle.
In FIG. 6, step 501 substitutes the temperature of the switching element 12 mounted on the DC / DC converter 100 for a variable T. In step 502, the current flowing through the DC / DC converter 100 is substituted into a variable I.

Step 503 confirms whether or not the instruction from the inverter control device 208 is a discharge sequence of the capacitor 204. If it is determined that the discharge sequence is (Y), the process proceeds to step 504. If it is determined that the discharge sequence is not (N), the process proceeds to step 507.
If step 504 is determined to be a discharge sequence in step 503, based on the conversion efficiency deterioration control table shown in FIG. 7, the temperature increase width xTf (I) corresponding to the current I due to the change of the drive frequency xf is set to the variable T Add to. Step 505 determines whether or not the temperature T obtained in Step 504 is equal to or higher than the upper limit temperature xTmax of the switching element 12. As a result of the determination, if the temperature T is equal to or higher than xTmax (Y), the process proceeds to step 507; otherwise (N), the process proceeds to step 506.

  Step 506 substitutes the drive frequency xf (I) for the drive frequency f corresponding to the current I based on the conversion efficiency deterioration control table shown in FIG. Step 507 substitutes the normal driving frequency xfn for the driving frequency f. Step 508 is provided with two circuits for switching the rising and falling slopes of the voltage across the switching element 12, and according to the conversion efficiency deterioration control table shown in FIG. The temperature increase width xTdv (I) is added to the variable T.

In step 509, it is determined whether or not the temperature T obtained in step 508 is equal to or higher than the upper limit temperature xTmax of the switching element 12. As a result of the determination, if the temperature T is equal to or higher than xTmax (Y), the process proceeds to step 511, and if not (N), the process proceeds to step 510.
In step 510, which one of the two circuits is used according to the current I is read from the conversion efficiency deterioration control table shown in FIG. 8, and is assigned to the flag flag. When the flag flag is “0”, the inclination is steeper, and when the flag flag is “1”, the inclination is controlled to be gentle.

In step 511, “0” is assigned to the flag flag so as to use a normal circuit (a circuit in which the rise / fall of the voltage across the switching element 12 is steep). In step 512, the temperature increase width xTv (I) corresponding to the current I due to the output voltage adjustment is added to the variable T based on the output voltage adjustment control table shown in FIG.
In step 513, it is determined whether or not the temperature T obtained in step 512 is equal to or higher than the upper limit temperature xTmax of the switching element 12. As a result of the determination, if the temperature T is equal to or higher than xTmax (Y), the process proceeds to step 515, and if not (N), the process proceeds to step 514.
Step 514 substitutes the target output voltage xV (I) corresponding to the current I for the target output voltage V based on the output voltage adjustment control table shown in FIG. In step 515, the target output voltage xVn at the normal time is substituted for the target output voltage V. Step 516 drives and controls the switching element 12 of the DC / DC converter 100 based on at least the values of the drive frequency f, the flag flag, and the target output voltage V.

  As described above, the conversion efficiency deterioration control by the drive frequency, the conversion efficiency deterioration control by switching the slope of the rise and fall of the voltage across the switching element 12, and the output voltage adjustment control are prioritized in the DC / DC converter. While predicting the temperature of the switching element 12 mounted on 100, it is determined whether or not to perform such control. As a result, the temperature of the switching element 12 mounted on the DC / DC converter 100 is operated within a predetermined upper limit temperature range, so that the capacitor 204 can be charged without causing the DC / DC converter 100 to fail. Can discharge.

  In the third embodiment, the conversion efficiency deterioration control data table according to the drive frequency shown in FIG. 7 and the output voltage adjustment control data table shown in FIG. Although described as changing, it may be set to change steplessly (linearly). Further, the temperature rise width also changes stepwise according to the current I, but it may be calculated by a predetermined calculation formula according to at least the current I.

In addition, regarding the conversion efficiency deterioration control by switching the rising and falling slopes of the voltage across the switching element 12, in the third embodiment, the two circuits are switched with the "0" or "1" flag. You may make it change in steps by three or more circuits. Alternatively, it may be realized by a stepless circuit.

  In the third embodiment, the temperature monitoring measurement point is implemented as the switching element 12. However, this may be performed by monitoring the temperature of the magnetic component (transformer 104, choke coil 108). Alternatively, the temperature of both the switching element 12 and the magnetic component is monitored, and the conversion efficiency deterioration control or the output voltage adjustment control is selectively executed depending on whether any one or more temperatures exceed the upper limit temperature. It doesn't matter.

  In the third embodiment, the conversion efficiency deterioration control or the output voltage adjustment control is selectively executed while monitoring the temperature. However, the discharge control of the capacitor 204 is completed in an extremely short time. If there is, this temperature monitoring may not be performed and the temperature sensor may not be mounted. By doing in this way, there exists an effect which leads to the cost reduction of an apparatus.

As described above, the invention of the third embodiment includes two or more of the conversion efficiency deterioration unit 210 and the output voltage adjustment unit 211, and according to the output current of the DC / DC converter 100 or an equivalent value thereof. Since the conversion efficiency deterioration means 210 and the output voltage adjustment means 211 are selectively executed according to the temperature of one or more of the switching element and magnetic component of the DC / DC converter 100, the temperature of the switching element or magnetic component rises. The discharge time can be shortened as compared with the prior art while keeping the value within a predetermined range, and the capacitor charge can be discharged within the target discharge time. Further, no additional discharge circuit other than the DC / DC converter is required, and the cost of the discharge circuit can be minimized.
Further, when the conversion efficiency deterioration unit 210 or the output voltage adjustment unit 211 is executed, the operation amount or the target value is determined in advance, and when the inverter controller 208 discharges the electric charge of the capacitor 204, the predetermined amount is determined. By executing so as to be within the range, the charge of the capacitor can be discharged without causing the DC / DC converter 100 to fail.

Embodiment 4 FIG.
Next, a vehicle power supply device according to Embodiment 4 of the present invention will be described with reference to FIG.
In the vehicular power supply apparatus according to the fourth embodiment, the DC / DC converter control device 209 includes both the conversion efficiency deterioration means 210 and the output voltage adjustment means 211 as in the third embodiment. The measurement means for measuring the output current and the measurement means for measuring the temperature of the switching element 12 are provided, and the illustration is omitted.

  Next, the control method of the vehicle power supply device of the present invention will be described with reference to the flowchart shown in FIG. FIG. 10 shows a flowchart when the conversion efficiency deterioration means 210 and the output voltage adjustment means 211 of the DC / DC converter control device 209 perform the conversion efficiency deterioration control and the output voltage adjustment control of the DC / DC converter 100. Are repeatedly executed in a predetermined cycle, for example, a 10 ms cycle.

In FIG. 10, step 901 assigns the temperature of the switching element 12 mounted on the DC / DC converter 100 to a variable T. Further, the current flowing through the DC / DC converter 100 is substituted into the variable I. Further, the base value of the loss contributing to the discharge of the smoothing capacitor 204 is set to the variable Eadd. This base value depends on the current I, and is determined by the internal resistance of the sub-battery 206 (assumed that it cannot be measured) and the resistance value of the load 207 of the auxiliary machine group. The residual energy Ec that needs to be discharged is obtained from the expression (1) from the charging voltage Vc of the smoothing capacitor 204 of the inverter device 203.
Ec = 1 / 2C ・ (Vc ^ 2−Vmin ^ 2) (1)
C: Capacity of the smoothing capacitor
Vmin: Voltage after discharge

Step 902 starts counting up the discharge elapsed time Tdis (the discharge elapsed time Tdis is reset immediately after the start of discharge). Step 903 confirms whether the instruction from the inverter control device 208 is a discharge sequence of the capacitor 204. If it is determined that the discharge sequence is (Y), the process proceeds to step 904, and if it is determined that the discharge sequence is not (N), the process proceeds to step 907.
If step 904 is determined to be a discharge sequence in step 903, based on the conversion efficiency deterioration control table shown in FIG. 7, the temperature rise width xTf (I) corresponding to the current I due to the change of the drive frequency xf is set to the variable T Add to. Further, an additional loss xLf (I) corresponding to the current I due to the drive frequency change is added to the variable Eadd.

  In step 905, whether the temperature T obtained in step 904 is equal to or higher than the upper limit temperature xTmax of the switching element 12 and the time required for discharge from the residual energy and the loss Eadd are obtained, and this time and the elapsed discharge time Tdis are added, It is determined whether or not the added value Q is less than the target discharge time Tdis_target. As a result of the determination, if the temperature T is equal to or higher than xTmax, or the added value Q is less than the target discharge time Tdis_target (discharge is completed within the target discharge time) (Y), the process proceeds to step 907; move on. Step 906 substitutes the drive frequency xf (I) for the drive frequency f corresponding to the current I based on the conversion efficiency deterioration control table shown in FIG. Step 907 substitutes the normal driving frequency xfn for the driving frequency f.

Step 908 is provided with two circuits for switching the slopes of the rise and fall of the voltage across the switching element 12, and according to the current I by these two circuits from the conversion efficiency deterioration control table shown in FIG. The temperature increase width xTdv (I) is added to the variable T. Further, the loss xLdv (I) corresponding to the current I by these two circuits is added to the variable L.
In step 909, whether the temperature T obtained in step 908 is equal to or higher than the upper limit temperature xTmax of the switching element 12, and the time required for discharge from the residual energy and the additional loss Eadd is obtained, and this time and the discharge elapsed time Tdis are added, It is determined whether this added value Q is less than the target discharge time Tdis_target. As a result of the determination, if the temperature T is equal to or higher than xTmax, or the added value Q is less than the target discharge time Tdis_target (discharge is completed within the target discharge time) (Y), the process proceeds to step 911, otherwise (N) to step 910 move on.

In step 910, which one of the two circuits is used according to the current I is read from the conversion efficiency deterioration control table shown in FIG. 8, and is substituted for the flag flag. When the flag flag is “0”, the inclination is steeper, and when the flag flag is “1”, the inclination is controlled to be gentle. Step 911 assigns “0” to the flag flag so as to use a normal circuit (a circuit in which the rise / fall of the voltage across the switching element 12 is steep).
In step 912, the temperature increase width xTdv (I) corresponding to the current I by the output voltage adjustment is added to the variable T based on the output voltage adjustment control table shown in FIG. Further, the loss xLv (I) corresponding to the current I due to the output voltage adjustment is added to the variable L.

In step 913, whether the temperature T obtained in step 912 is equal to or higher than the upper limit temperature xTmax of the switching element 12, the time required for discharge is obtained from the residual energy and the additional loss Eadd, and this time and the discharge elapsed time Tdis are added, It is determined whether this added value Q is less than the target discharge time Tdis_target. As a result of the determination, if the temperature T is equal to or higher than xTmax, or the added value Q is less than the target discharge time Tdis_target (discharge is completed within the target discharge time) (Y), the process proceeds to step 915, otherwise (N) to step 914 move on.
In step 914, the target output voltage xV (I) corresponding to the current I is substituted for the target output voltage V based on the output voltage adjustment control table shown in FIG. In step 915, the target output voltage xVn at the normal time is substituted for the target output voltage V. Step 916 drives and controls the switching element 12 of the DC / DC converter 100 based on at least the values of the driving frequency f, the flag flag, and the target output voltage V.

  As described above, the conversion efficiency deterioration control by the drive frequency, the conversion efficiency deterioration control by switching the slope of the rise and fall of the voltage across the switching element 12, and the output voltage adjustment control are prioritized in the DC / DC converter. Whether or not to execute these controls is determined while predicting the temperature of the switching element 12 mounted on 100 and determining whether or not the discharge can be performed within the target discharge time. As a result, as long as the target discharge time can be achieved, the loss of the DC / DC converter 100 is not increased unnecessarily, so that the DC / DC converter 100 is not damaged or the life deterioration is minimized. Meanwhile, the capacitor 204 can be discharged.

  In the fourth embodiment, the conversion efficiency deterioration control data table according to the driving frequency shown in FIG. 7 and the output voltage adjustment control data table shown in FIG. However, the setting may be changed steplessly (linearly). Further, the temperature rise width also changes stepwise according to the current I, but it may be calculated by a predetermined calculation formula according to at least the current I.

  In addition, regarding the conversion efficiency deterioration control by switching the rising and falling slopes of the voltage across the switching element 12, in the fourth embodiment, the two circuits are switched with the "0" or "1" flag. You may make it change in steps by three or more circuits. Alternatively, it may be realized by a stepless circuit.

  In the fourth embodiment, the temperature monitoring measurement point is implemented as the switching element 12. However, this may be performed by monitoring the temperature of the magnetic component (transformer 104, choke coil 108). Alternatively, the temperature of both the switching element 12 and the magnetic component is monitored, and the conversion efficiency deterioration control or the output voltage adjustment control is selectively executed depending on whether any one or more temperatures exceed the upper limit temperature. It doesn't matter if you do.

  As described above, according to the fourth embodiment, the temperature of any one or more of the switching element and the magnetic component mounted on the DC / DC converter 100 is measured and kept within the predetermined upper limit temperature range. As the first priority, the conversion efficiency deterioration unit 210 or the output voltage adjustment unit 211 is executed so that the discharge time of the capacitor 204 becomes a target value of a predetermined discharge time. It becomes possible to discharge the capacitor charge within the discharge time. Further, no additional discharge circuit other than the DC / DC converter is required, and the cost of the discharge circuit can be minimized. Furthermore, the capacitor charge can be discharged without causing the DC / DC converter to fail.

Embodiment 5 FIG.
Next, a vehicle power supply device according to Embodiment 5 of the present invention will be described with reference to FIG.
In the vehicular power supply apparatus according to the fifth embodiment, as in the third embodiment, the DC / DC converter control device 209 includes both the conversion efficiency deterioration means 210 and the output voltage adjustment means 211, and further includes an accident involving a vehicle collision. This is provided with means for detecting the occurrence of this, and is not shown here.

  Next, the control method of the vehicle power supply device of the present invention will be described with reference to the flowchart shown in FIG. FIG. 11 shows a flowchart when the conversion efficiency deterioration unit 210 and the output voltage adjustment unit 211 of the DC / DC converter control device 209 perform the conversion efficiency deterioration control and the output voltage adjustment control of the DC / DC converter 100. Are repeatedly executed in a predetermined cycle, for example, a 10 ms cycle.

  In FIG. 11, step 1001 confirms whether or not the instruction from the inverter control device 208 is a discharge sequence of the capacitor 204. Step 1002 sets the drive frequency f of the DC / DC converter 100 to a value xf1 larger than the set value xfn when not in the discharge sequence when it is determined in step 1001 that the discharge sequence is (Y). Step 1003 sets the drive frequency f of the DC / DC converter 100 to xfn when it is determined in Step 1002 that the discharge sequence is not (N). This xfn is a value that optimizes the power conversion of the DC / DC converter, and is ideally set to have the highest efficiency that can be realized by the converter.

In step 1004, it is confirmed from the inverter control device 208 or the like whether or not an accident has occurred in the host vehicle. If it is determined in step 1004 that no accident has occurred (N), step 1005 sets the target output voltage V of the DC / DC converter 100 to a value xV1 greater than the set value xVn when not in the discharge sequence.
If it is determined in step 1004 that an accident has occurred (Y), step 1006 sets the target output voltage V of the DC / DC converter 100 to a value xV3 at which the sub-battery 206 cannot be charged.

Step 1007 sets the target output voltage V of the DC / DC converter 100 to xVn when it is determined in step 1001 that the discharge sequence is not (N). This xVn is an optimal value for charging the sub-battery 206 in a healthy and continuous manner, and is ideally set so as to minimize the deterioration of the battery life while the sub-battery 206 is almost fully charged. is there.
In step 1008, the switching element 12 of the DC / DC converter 100 is driven and controlled based on at least the value of the driving frequency f and the target output voltage V.

  As described above, when an accident occurs, only the conversion efficiency deterioration means 210 of the conversion efficiency deterioration control and the output voltage adjustment control is executed, and the output voltage adjustment means 211 prevents the sub battery 206 from being charged. Therefore, when the sub-battery is destroyed due to an accident such as liquid leakage, the charge of the capacitor 204 can be discharged while coping with this.

  In the fifth embodiment, the output voltage adjustment control is not performed when an accident occurs. However, as described in the fourth embodiment, the target discharge time is emphasized, Only when the target discharge time cannot be achieved, the output voltage adjustment control may be performed. Alternatively, the target output voltage may be set as low as possible to achieve the target discharge time.

  As described above, the invention of Embodiment 5 preferentially executes the conversion efficiency deterioration means of the conversion efficiency deterioration means and the output voltage adjustment means, and the discharge time target value cannot be achieved by the conversion efficiency deterioration means alone. As long as the output voltage adjusting means is executed, the discharge time can be shortened compared to the conventional case, and the discharge of the capacitor charge is completed within the target discharge time. Moreover, no additional discharge circuit other than the DC / DC converter is required. The cost of the discharge circuit can be minimized. Furthermore, when an accident occurs, the charge of the capacitor can be discharged while caring for the destruction of the sub-battery.

Furthermore, when the target value of the discharge time cannot be achieved only by the conversion efficiency deterioration means, the output voltage adjusting means sets the target output voltage as low as possible to achieve the target value of the discharge time, so that it is more than conventional. The discharge time can be shortened, and the discharge of the capacitor charge is completed within the target discharge time.
Further, when an accident occurs, only the conversion efficiency deterioration means is executed out of the conversion efficiency deterioration means and the output voltage adjustment means, and the output voltage adjustment means is set to the target output voltage so as not to charge the sub-battery. The discharge time can be shortened, and the discharge of the capacitor charge is completed within the target discharge time.

Embodiment 6 FIG.
Next, a vehicle power supply device according to Embodiment 6 of the present invention will be described with reference to FIG.
In the vehicular power supply apparatus according to the sixth embodiment, the DC / DC converter control device 209 includes both the conversion efficiency deterioration unit 210 and the output voltage adjustment unit 211 as in the third embodiment, and is further similar to the fifth embodiment. Is provided with means for detecting the occurrence of an accident including a vehicle collision, and is not shown here.

  Next, the control method for the vehicle power supply device of the present invention will be described with reference to the flowchart shown in FIG. FIG. 12 shows a flowchart when the conversion efficiency deterioration means 210 and the output voltage adjustment means 211 of the DC / DC converter control device 209 perform the conversion efficiency deterioration control and the output voltage adjustment control of the DC / DC converter 100. Are repeatedly executed in a predetermined cycle, for example, a 10 ms cycle.

In FIG. 12, step 1101 confirms whether or not the instruction from the inverter control device 208 is a discharge sequence of the capacitor 204. When it is determined in step 1102 that the discharge sequence is (Y) in step 1101, it is confirmed from the inverter control device 208 or the like whether an accident has occurred in the host vehicle.
Step 1103 sets the drive frequency f of the DC / DC converter 100 to xfn when it is determined in step 1101 that the discharge sequence is not (N). This xfn is a value that optimizes the power conversion of the DC / DC converter 100, and is ideally set to have the highest efficiency that can be realized by the converter. Further, the target output voltage V of the DC / DC converter 100 is set to xVn. This xVn is an optimal value for charging the sub-battery 206 in a healthy and continuous manner, and is ideally set so as to minimize the deterioration of the battery life while the sub-battery 206 is almost fully charged. is there.

If it is determined in step 1102 that no accident has occurred (N), step 1104 sets the target output voltage V of the DC / DC converter 100 to a value xV1 that is larger than the set value xVn when not in the discharge sequence. Further, the drive frequency f of the DC / DC converter 100 is set to xfn. This xfn is a value that optimizes the power conversion of the DC / DC converter.
If it is determined in step 1102 that an accident has occurred (Y), step 1105 sets the drive frequency f of the DC / DC converter 100 to a value xf1 that is greater than the set value xfn when not in the discharge sequence. Further, the target output voltage V of the DC / DC converter is set to a value xV3 at which the sub-battery cannot be almost charged.
Step 1106 controls driving of the switching element 12 of the DC / DC converter 100 based on at least the values of the driving frequency f and the target output voltage V.

  As described above, when no accident occurs, the sub-battery 206 can be charged while suppressing energy loss by executing only the output voltage adjustment unit 211 of the conversion efficiency deterioration control and the output voltage adjustment control. Further, when an accident occurs, only the conversion efficiency deterioration means 210 is executed out of the conversion efficiency deterioration control and the output voltage adjustment control, and the output voltage adjustment means 211 is set to the target output voltage so as not to charge the sub battery 206. When the sub-battery is destroyed due to liquid leakage due to an accident, the charge of the capacitor can be discharged while coping with this.

In the sixth embodiment, the output voltage adjustment control is not performed when an accident does not occur. However, the target discharge time cannot be achieved by focusing on the target discharge time. Only in this case, the output voltage adjustment control may be performed. Alternatively, the target output voltage may be set as low as possible to achieve the target discharge time.
Of the conversion efficiency deterioration control and the output voltage adjustment control, the output voltage adjustment means 211 is preferentially executed, and the conversion efficiency deterioration means 210 is selectively executed to achieve the target value of the discharge time, whereby an accident occurs. If not, the sub-battery 206 can be charged while discharging the capacitor 204 within the target discharge time and suppressing energy loss.

As described above, according to the sixth embodiment, when an accident does not occur, the output voltage adjustment means is preferentially executed among the conversion efficiency deterioration means and the output voltage adjustment means, and the conversion is performed so as to achieve the target value of the discharge time. By selectively executing the efficiency deterioration means, when no accident occurs, the sub-battery can be charged while discharging the capacitor charge within the target discharge time and suppressing energy loss.
Further, when no accident occurs, by executing only the output voltage adjustment means of the conversion efficiency deterioration means and the output voltage adjustment means, when no accident occurs, the sub-battery can be charged while suppressing energy loss.

  It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

100: DC / DC converter, 12a-12d: switching element,
103: Inverter circuit, 104: Transformer, 107: Rectifier circuit,
202: Electric motor 203: Inverter device 204: Smoothing capacitor
205: main battery, 206: sub-battery, 207: load of auxiliary machinery group of the vehicle,
208: Inverter control device, 209: DC / DC converter control device,
210: Conversion efficiency deterioration means 211: Output voltage adjustment means

Claims (16)

An inverter device for driving the electric motor by converting DC power of the main battery into AC power, a smoothing capacitor connected in parallel to the inverter device, charge / discharge of the capacitor, and inverter control means for controlling the inverter device A sub-battery for supplying power to the inverter control means, and a DC / DC converter for charging the sub-battery by dropping a voltage of the main battery , and having a switching element for power conversion mounted therein DC / DC converter control means for performing power conversion by alternatively or steplessly controlling the drive frequency of the switching element of the DC / DC converter,
The inverter control means controls to supply a charge to the sub-battery or a device connected thereto via the DC / DC converter when the capacitor is discharged, and the DC / DC converter control means / DC converter losses have a conversion efficiency deterioration means better during discharge operation of the capacitor than in normal operation is controlled to be increased, the conversion efficiency deteriorates means to increase the driving frequency of the switching element switching A power supply device for a vehicle, which is controlled to increase loss . An inverter device for driving the electric motor by converting DC power of the main battery into AC power, a smoothing capacitor connected in parallel to the inverter device, charge / discharge of the capacitor, and inverter control means for controlling the inverter device A sub-battery for supplying power to the inverter control means, and a DC / DC converter for charging the sub-battery by dropping a voltage of the main battery, and having a switching element for power conversion mounted therein A DC / DC converter having means for alternatively or steplessly controlling the slope of the rise and fall of the voltage across the switching element of the DC / DC converter , or the slope of the change of either one of them Control means,
The inverter control means controls to supply a charge to the sub-battery or a device connected thereto via the DC / DC converter when the capacitor is discharged, and the DC / DC converter control means / Conversion efficiency deterioration means for controlling the loss of the DC converter to be larger during the capacitor discharge operation than during normal operation, the conversion efficiency deterioration means, the slope of the change of the rising and falling, or either one as the slope of one of the changes go to bed, car dual power supply you and controlling the switching element. An inverter device for driving the electric motor by converting DC power of the main battery into AC power, a smoothing capacitor connected in parallel to the inverter device, charge / discharge of the capacitor, and inverter control means for controlling the inverter device And a sub-battery for supplying power to the inverter control means, and an isolated converter having a transformer inside, and having a power conversion switching element mounted therein, and lowering the voltage of the main battery. A DC / DC converter that charges the sub-battery, and a DC / DC converter control means that performs power conversion by alternatively or steplessly controlling the drive frequency of the switching element of the DC / DC converter,
The inverter control means controls to supply a charge to the sub-battery or a device connected thereto via the DC / DC converter when the capacitor is discharged, and the DC / DC converter control means Conversion efficiency deterioration means for controlling the loss of the DC converter to be greater during the capacitor discharge operation than during normal operation, the conversion efficiency deterioration means lowering the drive frequency of the switching element car dual power supply characterized in that the iron loss of the transformer is controlled to be increased. An inverter device for driving the electric motor by converting DC power of the main battery into AC power, a smoothing capacitor connected in parallel to the inverter device, charge / discharge of the capacitor, and inverter control means for controlling the inverter device A sub battery that supplies power to the inverter control means, a DC / DC converter that charges the sub battery by dropping the voltage of the main battery, and DC / DC that controls power conversion of the DC / DC converter Converter control means,
The DC / DC converter is an insulating converter having a transformer inside, a switching element provided on a primary side of the transformer, a switching element provided on a secondary side of the transformer, and the transformer 1 Means for selectively or steplessly controlling the dead time of the switching element on the secondary side and the switching element on the secondary side of the transformer, and the inverter control means is configured to charge the DC / DC converter when the capacitor is discharged. The DC / DC converter control means controls the loss of the DC / DC converter during the discharging operation of the capacitor than during the normal operation. has a conversion efficiency deterioration means for controlling such increases, the conversion efficiency deteriorates means, said dead time Further to drive the dual power supply you and performing in. An inverter device for driving the electric motor by converting DC power of the main battery into AC power, a smoothing capacitor connected in parallel to the inverter device, charge / discharge of the capacitor, and inverter control means for controlling the inverter device A sub battery that supplies power to the inverter control means, a DC / DC converter that charges the sub battery by dropping the voltage of the main battery, and DC / DC that controls power conversion of the DC / DC converter Converter control means,
The DC / DC converter is an insulating converter having a transformer inside, a switching element provided on a primary side of the transformer, a switching element provided on a secondary side of the transformer, and the transformer 1 Means for controlling the drive timing of the secondary side switching element and the transformer secondary side switching element in an alternative or stepless manner, and the inverter control means transfers the electric charge to the DC / DC converter when the capacitor is discharged. The DC / DC converter control means controls the loss of the DC / DC converter during the discharging operation of the capacitor than during the normal operation. has a conversion efficiency deterioration means for controlling such increases, the conversion efficiency deteriorates means, said driving timing Car dual power supply you and performing by changing the. An inverter device for driving the electric motor by converting DC power of the main battery into AC power, a smoothing capacitor connected in parallel to the inverter device, charge / discharge of the capacitor, and inverter control means for controlling the inverter device A sub battery that supplies power to the inverter control means, a DC / DC converter that charges the sub battery by dropping the voltage of the main battery, and DC / DC that controls power conversion of the DC / DC converter Converter control means,
The inverter control means controls to supply a charge to the sub-battery or a device connected thereto via the DC / DC converter when the capacitor is discharged, and the DC / DC converter control means / with DC converter output voltage is controlled to be a desired target value, an output voltage adjusting means for controlling the output voltage during discharge of the capacitor is set higher than the target value, said output voltage adjustment means, the before and after the inverter control means to discharge the capacitor, the vehicle dual power supply you and sets the target output voltage so that the change in the DC / DC converter output voltage is reduced. An inverter device for driving the electric motor by converting DC power of the main battery into AC power, a smoothing capacitor connected in parallel to the inverter device, charge / discharge of the capacitor, and inverter control means for controlling the inverter device A sub battery that supplies power to the inverter control means, a DC / DC converter that charges the sub battery by dropping the voltage of the main battery, and DC / DC that controls power conversion of the DC / DC converter Converter control means,
The inverter control means controls to supply a charge to the sub-battery or a device connected thereto via the DC / DC converter when the capacitor is discharged, and the DC / DC converter control means Conversion efficiency deteriorating means for controlling the loss of the DC / DC converter to be greater during the discharging operation of the capacitor than during the normal operation, and the output voltage of the DC / DC converter during the discharging operation of the capacitor from during the normal operation Output voltage adjusting means for controlling the output voltage to become larger, and the conversion efficiency deterioration means and the output voltage adjusting means are selectively executed in accordance with the temperature state of the DC / DC converter. Power supply. The DC / DC converter control means has measurement means for measuring the output current of the DC / DC converter, and when the inverter control means discharges the capacitor, according to the current value measured by the measurement means. The vehicle power supply device according to claim 7 , wherein one of the conversion efficiency deterioration unit and the output voltage adjustment unit is selected and executed. The DC / DC converter control means has measuring means for measuring the temperature of at least one of a switching element and a magnetic component mounted on the DC / DC converter, and the inverter control means discharges the capacitor. 8. The method according to claim 7 , wherein when performing, at least one of the conversion efficiency deterioration means and the output voltage adjustment means is selected and executed so that the temperature falls within a predetermined upper limit temperature range. The power supply device for vehicles as described. When the inverter control means discharges the capacitor, the DC / DC converter control means predetermines at least the discharge time of the capacitor, with the first priority being at least that the temperature falls within a predetermined upper temperature range. and so that the target value of the discharge time, and select one of whether to perform the conversion efficiency deterioration means or the output voltage adjusting means, also according to claim 9, characterized by adjusting the operation amount or the target value Vehicle power supply device. Means for detecting the occurrence of an accident including a vehicle collision, and at the time of occurrence of the accident, the conversion efficiency deterioration means is preferentially executed among the conversion efficiency deterioration means and the output voltage adjustment means, and a target value of discharge time The vehicle power supply device according to claim 7 , wherein the output voltage adjusting means is executed only when the above-mentioned cannot be achieved. When the accident occurs, the output voltage adjusting means sets the target output voltage as low as possible to achieve the target value of the discharge time when the target discharge time cannot be achieved only by the conversion efficiency deterioration means. The vehicular power supply device according to claim 11 . Means for detecting the occurrence of an accident including a vehicle collision, and when the accident occurs, only the conversion efficiency deterioration means is executed among the conversion efficiency deterioration means and the output voltage adjustment means, and the output voltage adjustment means 8. The vehicle power supply device according to claim 7 , wherein the target output voltage is set so as not to charge the sub-battery. Means for detecting the occurrence of an accident including a vehicle collision, and when no accident occurs, the output voltage adjusting means is preferentially executed among the conversion efficiency deteriorating means and the output voltage adjusting means, and a discharge time target 8. The vehicle power supply device according to claim 7 , wherein the conversion efficiency deterioration means is selectively executed to achieve a value. Means for detecting the occurrence of an accident including a vehicle collision, and when no accident occurs, only the output voltage adjusting means is executed among the conversion efficiency deteriorating means and the output voltage adjusting means, and the conversion efficiency deteriorating means is provided. The vehicular power supply device according to claim 7 , wherein the vehicular power supply device is not executed. The conversion efficiency deterioration means, two or more conversion efficiency deterioration means according to any one of claims 1 to 5, and the output voltage adjusting means comprises an output voltage adjustment means according to claim 6 The vehicular power supply device according to any one of claims 7 to 15 , wherein the vehicular power supply device is provided.

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