JP2015201945A - On-vehicle power supply apparatus and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To limit an output current.SOLUTION: The on-vehicle power supply apparatus includes: a voltage conversion section for voltage-converting an input voltage; a first control section for controlling a voltage conversion operation of the voltage conversion section to obtain an output voltage value based on an output voltage preset value; and a second control section for variably controlling the output voltage preset value so that an input current value in the voltage conversion section approaches an input current limit value instructed by an on-vehicle side control section.

Description

  The present invention relates to an in-vehicle power supply device that converts an input voltage into a voltage, and a control method for the in-vehicle power supply device.

  In recent years, in-vehicle LAN (Local Area Network) represented by CAN (Control Area Network) has been installed in automobiles, and each function of the automobile is electronically controlled by an in-vehicle side controller called ECU (Electric Control Unit). Has been. An in-vehicle power supply device (DC / DC converter) mounted on a hybrid vehicle or the like is also connected to the in-vehicle LAN, and states such as input / output voltage and input / output current can be controlled by the ECU.

Japanese Patent No. 4432115

  Patent Document 1 describes overcurrent control in a switching power supply device. In the switching power supply device, the output current can be limited based on a preset value of overcurrent protection.

  On the other hand, power is supplied from a high-voltage battery to a DC / DC converter for a hybrid vehicle, and an inverter is connected to the high-voltage battery, and power may also be supplied to the inverter. In this case, when it is desired to supply power preferentially to the inverter, it is necessary to limit power supply to the DC / DC converter. However, the method of limiting the output current based on the set value of the overcurrent protection has a limit in limiting the output current.

  The objective of this invention is providing the control method of the vehicle-mounted power supply device which enabled it to restrict | limit an output current, and a vehicle-mounted power supply device.

  An in-vehicle power supply device according to the present invention includes a voltage conversion unit that converts an input voltage into a voltage, a first control unit that controls a voltage conversion operation of the voltage conversion unit so as to obtain an output voltage value based on an output voltage setting value, And a second control unit that variably controls the output voltage setting value so that the input current value in the voltage conversion unit approaches the input current limit value instructed from the in-vehicle side control unit.

  The control method of the in-vehicle power supply device according to the present invention controls the voltage conversion operation of the voltage conversion unit so that the output voltage value is based on the output voltage setting value, and the input current value in the voltage conversion unit is Thus, the output voltage set value is variably controlled so as to approach the input current limit value instructed from.

  In the on-vehicle power supply device or the on-vehicle power supply device control method according to the present invention, the voltage conversion operation of the voltage conversion unit is controlled so that the output voltage value is based on the output voltage setting value. At this time, the output voltage set value is variably controlled so that the input current value in the voltage conversion unit approaches the input current limit value instructed from the in-vehicle side control unit.

  The in-vehicle power supply device according to the present invention further includes an overcurrent protection setting unit that sets an overcurrent protection setting command value for limiting the output current in the first control unit, and the second control unit includes an input current value The output voltage setting value may be variably controlled so that becomes lower than the current value based on the overcurrent protection setting command value.

In the in-vehicle power supply device according to the present invention, a first battery may be connected to the output terminal of the voltage conversion unit.
In this case, the differential voltage between the output voltage of the voltage converter and the battery voltage of the first battery may be controlled by variably controlling the output voltage set value.

  In the in-vehicle power supply device according to the present invention, an input terminal of the voltage conversion unit is connected to an inverter and a second battery that supplies power to the voltage conversion unit, and the second control unit is configured to supply power required by the inverter. The output voltage set value may be variably controlled so that the input current value becomes lower than the current value based on the overcurrent protection setting command value when the value exceeds a predetermined threshold.

  In the in-vehicle power supply device according to the present invention, when the input current value does not exceed the input current limit value, the second control unit sets the output voltage command value instructed by the in-vehicle side control unit as the output voltage setting. When the input current value exceeds the input current limit value, a setting value lower than the output voltage command value may be set as the output voltage setting value.

  According to the vehicle power supply device or the vehicle power supply control method of the present invention, the output voltage set value is set so that the input current value in the voltage conversion unit approaches the input current limit value instructed from the vehicle control unit. Since the variable control is performed, the output current can be limited.

It is a block diagram which shows one structural example of the power supply device which concerns on one embodiment of this invention. It is a block diagram which shows the example of 1 structure of the peripheral circuit of a power supply device. It is a circuit diagram which shows one structural example of an overcurrent protection setting part. It is explanatory drawing which shows an example of control of overcurrent protection. It is a flowchart which shows an example of control of the input current by output voltage control.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The description will be given in the following order.
1. Configuration 2. Operation 2.1 Basic operation of voltage conversion 2.2 Output voltage setting operation (example of current limiting operation)
3. Effect 4. Other embodiments

[1. Constitution]
FIG. 1 shows a configuration example of a DC / DC converter 1 as a power supply device according to an embodiment of the present invention.

  The DC / DC converter 1 includes input terminals T1 and T2 as input units, an input filter 11, a bridge circuit 12, a transformer 13, an output filter 14, output terminals T3 and T4 as output units, and a terminal T5. And. The bridge circuit 12, the transformer 13, and the output filter 14 constitute a voltage conversion unit 10. The DC / DC converter 1 also includes a control IC (Integrated Circuit) 15, a microcomputer (microcontroller) 16, a current transformer 17, a current sense circuit 18, an output voltage sense circuit 19, and an input voltage sense circuit 20. It has.

  The DC / DC converter 1 is used, for example, for in-vehicle use, and generates a DC output voltage by converting (stepping down) the DC input voltage input from the high voltage battery BH by the voltage converter 10. It has become. This output voltage is supplied to the low voltage battery BL via the output terminals T3 and T4. The high voltage battery BH is a battery that stores a voltage of, for example, about 100V to 500V, and the low voltage battery BL is a battery that stores a voltage of, for example, about 12V to 15V. The high voltage battery BH is connected to the input terminals T1 and T2. A load 101 is connected to the low voltage battery BL side. The DC / DC converter 1 is connected to an ECU 100 which is a vehicle-mounted side control unit via a terminal T5.

  The control IC 15 corresponds to a specific example of “first control unit” in the invention. The microcomputer 16 corresponds to a specific example of “second control unit” in the invention. The high voltage battery BH corresponds to a specific example of “second battery” in the present invention, and the low voltage battery BL corresponds to a specific example of “first battery” in the present invention.

  The input filter 11 is for preventing the noise generated in the voltage converter 10 from flowing out to the high voltage battery BH side.

  The bridge circuit 12 includes a plurality of switching elements SW, and is composed of, for example, a full bridge type switching circuit that converts an input voltage into an AC voltage. For example, an element such as a MOS-FET (Metal Oxide Semiconductor-Field Effect Transistor) or an IGBT (Insulated Gate Bipolar Transistor) can be used as the switching element SW.

  In the bridge circuit 12, on the basis of the drive signal Ds1 supplied from the control IC 15, the switching element SW is turned on / off by, for example, PWM (Pulse Width Modulation) control, thereby converting the input voltage into an AC voltage. ing.

  The transformer 13 includes, for example, a primary side winding and a secondary side winding. If the turns ratio of the primary winding and the secondary winding is Np: Ns, the transformer 13 steps down the AC voltage supplied across the primary winding Ns / Np times 2 Output from the secondary winding.

  The output filter 14 is configured to include, for example, a rectifying element (diode) and a smoothing circuit, and rectifies and smoothes the AC voltage from the transformer 13 to generate a DC output voltage.

  The current transformer 17 is disposed between the input side of the voltage conversion unit 10 and between the input filter 11 and the bridge circuit 12 so as to output an input current sense signal Isin corresponding to the input current to the current sense circuit 18 and the control IC 15. It has become. The current sense circuit 18 outputs signals indicating the input current value Iin and the output current value Io to the microcomputer 16 based on the input current sense signal Isin. The output current value Io can be obtained by calculation from the input voltage sense signal uHV, the output voltage sense signal uLV, and the power conversion efficiency based on the input current value Iin.

  The input voltage sense circuit 20 is connected between the input side of the voltage converter 10, the input filter 11 and the bridge circuit 12, and outputs an input voltage sense signal uHV indicating an input voltage value to the microcomputer 16. .

  The output voltage sense circuit 19 is connected to the output side of the voltage converter 10 and outputs an output voltage sense signal uLV indicating an output voltage value to the microcomputer 16 and the control IC 15.

  The control IC 15 generates a drive signal Ds1 for PWM control of the switching element SW of the bridge circuit 12. The control IC 15 controls the voltage conversion operation of the bridge circuit 12 in the voltage conversion unit 10 so that the output voltage value is based on the output voltage setting value Vs1.

  The microcomputer 16 outputs a control signal for controlling the operation of the control IC 15 to the control IC 15 based on the control signal from the ECU 100. The microcomputer 16 is input with signals indicating the output voltage command value Vsig and the input current limit value Isig as control signals from the ECU 100. The microcomputer 16 outputs signals indicating the overcurrent protection setting command value Is2 and the output voltage setting value Vs1 to the control IC 15 as control signals.

  As will be described later, the microcomputer 16 variably controls the output voltage set value Vs1 so that the input current value approaches the input current limit value Isig instructed from the ECU 100 as necessary.

  As will be described later, the microcomputer 16 also variably controls the output voltage setting value Vs1 so that the input current value becomes lower than the current value based on the overcurrent protection setting command value Is2, as will be described later. Yes.

  As will be described later, the microcomputer 16 also variably controls the output voltage set value Vs1 as necessary to control the differential voltage between the output voltage and the battery voltage of the low-voltage battery BL as the first battery. It has become.

  The microcomputer 16 also outputs the output voltage setting value Vs1 so that the input current value becomes lower than the current value based on the overcurrent protection setting command value Is2 when the power required by the inverter 102 described later exceeds a predetermined threshold value. Is variably controlled.

  As will be described later, when the input current value does not exceed the input current limit value, the microcomputer 16 sets the output voltage command value Vsig instructed from the ECU 100 as the output voltage set value Vs1, and the input current value is When the input current limit value is exceeded, a set value lower than the output voltage command value Vsig is set as the output voltage set value Vs1.

[2. Operation]
(2.1 Basic operation of voltage conversion)
In FIG. 1, the bridge circuit 12 performs switching control of the switching element SW based on the drive signal Ds1, thereby converting a DC input voltage supplied from the high voltage battery BH into an AC voltage. Supply to the wire. The transformer 13 transforms (steps down) the AC voltage to Ns / Np times, and outputs the transformed AC voltage from the secondary winding. The output filter 14 rectifies and smoothes the AC voltage to generate a DC output voltage, and supplies power to the low voltage battery BL connected to the output terminals T3 and T4. Further, an output current and an output voltage are supplied to the load 101.

(2.2 Output voltage setting operation (example of current limiting operation))
The output voltage setting operation (current limiting operation example) will be described below with reference to FIGS. FIG. 2 shows a configuration example of a peripheral circuit of the DC / DC converter 1. FIG. 3 shows a configuration example of the overcurrent protection setting unit 22. FIG. 4 shows an example of current limitation by overcurrent protection.

  First, an example of a normal current limiting operation described in Patent Document 1 (Japanese Patent No. 4432115) will be described. In the switching power supply device, the output current can be limited based on a preset value of overcurrent protection. For example, as shown in FIG. 4, the output current can be limited by lowering the overcurrent protection setting value (overcurrent protection setting command value Is2). However, in the DC / DC converter 1 for a hybrid vehicle, when power is supplied to the low voltage battery BL and the load 101, there is a problem that the output current cannot be sufficiently limited with the normal overcurrent protection setting value. This will be described below.

  As shown in FIG. 3, the case where the overcurrent protection setting unit 22 is configured by resistance elements R1, R2, and R3 will be described as an example. In the DC / DC converter 1 for a hybrid vehicle, there is a demand for enabling the load 101 to be supplied even when the microcomputer 16 stops operating due to latch-up or the like. In FIG. 3, even if the overcurrent protection setting command value of the microcomputer 16 becomes zero because the microcomputer 16 stops, the control IC 15 gives the voltage Vcc as the overcurrent protection setting command value (overcurrent protection setting command value Is2). Is divided by the three resistance elements R1, R2 and R3. Therefore, the DC / DC converter 1 can supply a load up to an overcurrent protection setting value (overcurrent protection setting command value Is2) determined by a voltage value designed by dividing the resistance.

  On the other hand, when it is desired to supply power preferentially to the inverter 102 (FIG. 2) during acceleration or the like, there is a demand to have a function of further reducing the power supply to the DC / DC converter 1 more than the reduced output current. . However, as described above, when the output current is limited based on the setting value of overcurrent protection, the load current value that can be limited is determined. Therefore, in the present embodiment, the following current limiting operation is performed.

  FIG. 2 shows an example of the peripheral configuration of the DC / DC converter 1 for a hybrid vehicle. The inverter 102 and the DC / DC converter 1 are connected from the high voltage battery BH, and the low voltage battery BL and the load 101 are connected to the output of the DC / DC converter 1. The current limiting method according to the present embodiment uses the impedance of the wiring 103 between the outputs of the low voltage battery BL and the DC / DC converter 1 when power is supplied to the load 101 by the DC / DC converter 1. This is a method for controlling the input current value Iin.

  Controlling the voltage applied to the wiring 103 between the low voltage battery BL and the DC / DC converter 1 by controlling the output voltage value so that the input current becomes the set current value (overcurrent protection setting command value Is2). To control the input current.

  In order to reduce the power supplied from the high-voltage battery BH to the DC / DC converter 1, it is only necessary to control the DC / DC converter 1 so that it cannot supply the output current. Normally, this can be achieved by lowering the overcurrent protection setting command value Is2. However, as described above, even if the microcomputer 16 becomes unusable, the control current can be controlled only by the control IC 15 in order to reduce the output current. There are also limits.

Therefore, it is considered to limit the output current of the DC / DC converter 1 by controlling (lowering) the output voltage. However, as a premise thereof, the low voltage battery BL needs to be connected to the output of the DC / DC converter 1. In principle, the output current is controlled by the impedance of the wiring 103 between the DC / DC converter 1 and the low voltage battery BL by controlling the voltage difference between the output voltage and the battery voltage of the low voltage battery BL.
Output current = (Output voltage-Battery voltage) / Wiring impedance

  FIG. 5 shows an example of input current control by output voltage control. An input current limit value signal Isig is transmitted from the ECU 100 to the microcomputer 16. The microcomputer 16 receives the input current limit value signal Isig and the input current value signal Iin actually flowing from the current sense circuit 18 to the DC / DC converter 1 and compares them. To do. Thereby, the microcomputer 16 determines whether or not the input current value Iin exceeds the input current limit value Isig (step S101).

  When the input current value Iin does not exceed the input current limit value Isig (Isig ≧ Iin) (step S101; N), the normal operation mode is set, and the microcomputer 16 outputs the output voltage command value Vsig (for example, 14.5V) transmitted from the ECU 100. ) Is set as the output voltage target value as it is (step S103).

  When the input current value Iin exceeds the input current limit value Isig (Isig <Iin) (step S101; Y), the input current limit mode is set, and the microcomputer 16 has a predetermined set lower limit value previously held in the microcomputer 16. (For example, 10.6V) is set as the output voltage target value (step S102).

  Next, the microcomputer 16 performs control to bring the output voltage set value Vs1 output to the control IC 15 closer to the output voltage target value set in steps S102 and S103. First, the microcomputer 16 determines whether or not the current output voltage setting value Vs1 exceeds the output voltage target value (step S104).

  When the output voltage set value Vs1 does not exceed the output voltage target value (step S104; N), the microcomputer 16 determines whether or not the output voltage target value exceeds the output voltage set value Vs1 (step S106). When the output voltage target value does not exceed the output voltage set value Vs1 (step S106; N), the output voltage target value = the output voltage set value Vs1. When the output voltage target value exceeds the output voltage set value Vs1 (step S106; Y), the microcomputer 16 adds the set value until the output voltage set value Vs1 becomes the output voltage target value (step S107). End the process.

  When the output voltage set value Vs1 exceeds the output voltage target value (step S104; Y), the microcomputer 16 subtracts the set value until the output voltage set value Vs1 becomes the output voltage target value (step S105). End the process.

  By the above control, the output voltage set value Vs1 is adjusted until finally Isig = Iin, and the output voltage is stabilized at a voltage satisfying Isig = Iin.

[3. effect]
As described above, according to the present embodiment, the output voltage set value Vs1 is variably controlled as necessary so that the input current value Iin approaches the input current limit value Isig instructed from the ECU 100. As a result, the output current can be further reduced below the current value limited by the overcurrent protection.

  In the current control method according to the present embodiment, for example, in a system for a hybrid vehicle, an output current cannot be limited by an overcurrent protection setting command (overcurrent protection setting command value Is2) used in a normal DC / DC converter. In addition, this is an effective method for further limiting the output current. In Patent Document 1 (Japanese Patent No. 4432115), the limit of the output current is controlled by the overcurrent protection set value. However, in this embodiment, the output current is limited by controlling the output voltage.

[4. Other Embodiments]
The technology according to the present invention is not limited to the description of the above embodiment, and various modifications can be made.

  For example, although the switching power supply device having the switching element SW has been described in the above embodiment, a power supply device other than the switching power supply device may be used.

  DESCRIPTION OF SYMBOLS 1 ... DC / DC converter (vehicle-mounted power supply device), 10 ... Voltage conversion part, 11 ... Input filter, 12 ... Bridge circuit, 13 ... Transformer, 14 ... Output filter, 15 ... Control IC, 16 ... Microcomputer, 17 ... Current Transformer, 18 ... current sense circuit, 19 ... output voltage sense circuit, 20 ... input voltage sense circuit, 22 ... overcurrent protection setting unit, 100 ... ECU, 101 ... load, 102 ... inverter, 103 ... wiring, BH ... high voltage battery , BL: low voltage battery, SW: switching element, T1, T2 ... input terminal, T3, T4 ... output terminal, T5 ... terminal, Ds1 ... drive signal, Iin ... input current value, Io ... output current value, Isin ... input current Sense signal, Vs1... Output voltage set value, Vsig... Output voltage command value, uLV... Output voltage sense signal (output voltage value), uHV. Power Voltage Sense signal (input voltage value), Is2 ... overcurrent protection setting command value, Isig ... input current limit, R1, R2, R3 ... resistor element.

Claims (6)

A voltage converter for converting the input voltage to a voltage;
A first control unit that controls a voltage conversion operation of the voltage conversion unit so as to be an output voltage value based on an output voltage setting value;
A vehicle-mounted power supply device comprising: a second control unit that variably controls the output voltage setting value so that an input current value in the voltage conversion unit approaches an input current limit value instructed by the vehicle-mounted control unit. An overcurrent protection setting unit that sets an overcurrent protection setting command value for limiting the output current in the first control unit;
The in-vehicle power supply device according to claim 1, wherein the second control unit variably controls the output voltage setting value so that the input current value is lower than a current value based on the overcurrent protection setting command value. . A first battery is connected to an output terminal of the voltage converter;
The said 2nd control part controls the differential voltage of the output voltage of the said voltage conversion part, and the battery voltage of a said 1st battery by carrying out the variable control of the said output voltage setting value. In-vehicle power supply. A second battery that supplies power to the inverter and the voltage converter is connected to the input terminal of the voltage converter,
The second control unit is configured to output the output voltage so that the input current value is lower than a current value based on the overcurrent protection setting command value when power required by the inverter exceeds a predetermined threshold. The in-vehicle power supply device according to claim 2, wherein the set value is variably controlled. The second controller is
If the input current value does not exceed the input current limit value, set the output voltage command value instructed from the vehicle-mounted side control unit as the output voltage set value,
5. The vehicle-mounted device according to claim 1, wherein when the input current value exceeds the input current limit value, a setting value lower than the output voltage command value is set as the output voltage setting value. Power supply. Control the voltage conversion operation of the voltage converter so that the output voltage value is based on the output voltage setting value,
A control method for an in-vehicle power supply device, wherein the output voltage set value is variably controlled so that an input current value in the voltage conversion unit approaches an input current limit value instructed from an in-vehicle side control unit.

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