JP2022095078A - On-vehicle power supply device - Google Patents

Abstract

To improve resolution of duty of an on-off signal used for voltage conversion.SOLUTION: An on-vehicle power supply device 1 has a voltage conversion part 10, a calculation part 32, and a signal generation part 34. The voltage conversion part 10 outputs voltage after stepping up or stepping down applied to a first conducting path 81 by an on-off operation of a switching element according to an on-off signal to a second conducting path 82. The calculation part 32 determines a period T and an on time Hon of the on-off signal. The signal generation part 34 generates the on-off signal at the period T and the on time Hon determined by the calculation part 32. The calculation part 32 calculates a duty target value Dtg by a feedback calculation based on output voltage and target voltage, determines the on time Hon based on the duty target value Dtg and a reference period Ts, and determines the period T based on the duty target value Dtg and the on time Hon.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to an in-vehicle power supply device.

The background technique of Patent Document 1 discloses a switching voltage regulator. This switching voltage regulator operates as a buck converter that utilizes pulse width modulation (PWM) to provide a voltage output smaller than the input voltage.

Japanese Patent Publication No. 2014-507114

The PWM signal that operates the buck converter as described above is generated by, for example, a microcomputer. The microcomputer calculates the duty of the PWM signal based on, for example, the output voltage of the buck converter and the target voltage, and generates a PWM signal of the duty obtained by the calculation. However, the on-time resolution for generating the PWM signal depends on the clock frequency of the microcomputer. Therefore, there may be a difference between the duty obtained by the calculation and the duty of the PWM signal actually generated. This difference is preferably small in order to improve the accuracy of voltage conversion, and can be made smaller by increasing the resolution of the duty of the on / off signal used for voltage conversion.

Therefore, an object of the present disclosure is to provide a technique capable of increasing the resolution of the duty of an on / off signal used for voltage conversion.

The in-vehicle power supply device of the present disclosure is
It has a switching element that operates on and off in response to an on / off signal with an on-time and period set, and boosts the voltage applied to the first conductive path by the on / off operation of the switching element in response to the on / off signal. Or a voltage converter that steps down and outputs to the second conductive path,
An arithmetic unit that determines the period and on-time of the on / off signal, and
A signal generation unit that generates the on / off signal in the cycle and the on time determined by the calculation unit, and
Have,
The calculation unit calculates a duty target value by a feedback calculation based on an output voltage and a target voltage, determines the on-time based on the duty target value and a reference period, and sets the duty target value and the on-time. The cycle is determined based on this.

According to the present disclosure, it is possible to increase the resolution of the duty of the on / off signal used for voltage conversion.

FIG. 1 is a circuit diagram schematically showing a configuration of an in-vehicle power supply system according to the first embodiment. FIG. 2 is a flowchart showing the flow of signal generation processing in the first embodiment. FIG. 3 is a flowchart showing the flow of signal generation processing in the second embodiment. FIG. 4 is a flowchart showing the flow of signal generation processing in the third embodiment. FIG. 5 is a flowchart showing the flow of signal generation processing in the fourth embodiment.

[Explanation of Embodiments of the present disclosure]
Hereinafter, embodiments of the present disclosure are listed and exemplified.

[1] It has a switching element that operates on and off in response to an on / off signal for which an on time and a period are set, and is applied to the first conductive path by the on / off operation of the switching element in response to the on / off signal. A voltage conversion unit that boosts or lowers the voltage and outputs it to the second conductive path, a calculation unit that determines the cycle and on-time of the on / off signal, and the cycle and on-time determined by the calculation unit. It has a signal generation unit that generates the on / off signal, and the calculation unit calculates a duty target value by feedback calculation based on an output voltage and a target voltage, and the calculation unit calculates the duty target value based on the duty target value and a reference period. An in-vehicle power supply device that determines a time and determines the cycle based on the duty target value and the on-time.

This in-vehicle power supply device determines the on-time based on the duty target value and the reference cycle, and determines the cycle based on the duty target value and the on-time. That is, the in-vehicle power supply device can further adjust the cycle after determining the on-time. Therefore, this in-vehicle power supply device can increase the resolution of the duty of the on / off signal used for voltage conversion as compared with the PWM signal having a fixed period.

[2] The calculation unit can select the cycle with a predetermined cycle resolution, and when the cycle is determined based on the duty target value and the on-time, a plurality of selectable cycle candidate values can be selected. The vehicle-mounted power supply device according to [1], wherein a value having a duty close to the duty target value is selected as the period.

When the cycle is determined based on the duty target value and the on-time, the vehicle-mounted power supply device selects a value having a duty close to the duty target value from a plurality of selectable cycle candidate values as the cycle. Therefore, this in-vehicle power supply device can generate an on / off signal having a duty closer to the duty target value as compared with a PWM signal having a fixed period. Therefore, according to this in-vehicle power supply device, the accuracy of voltage conversion can be further improved.

[3] The calculation unit can select the on-time with a predetermined on-time resolution, and obtains the duty target value by multiplying the reference period from the selectable on-time candidate values. The vehicle-mounted power supply device according to [1] or [2], wherein a value close to the multiplication value to be obtained is selected as the on-time.

According to this in-vehicle power supply device, the process of determining the on-time can be simplified.

<First Embodiment>
[Configuration of in-vehicle power supply system]
The vehicle-mounted power supply system 100 shown in FIG. 1 includes a first power storage unit 91, a second power storage unit 92, and an vehicle-mounted power supply device 1.

The first power storage unit 91 is composed of a known battery such as a lithium ion battery. The first power storage unit 91 is not limited to the lithium ion battery, and may be another type of battery configured to be chargeable / dischargeable. The terminal on the high potential side, which is the terminal having the highest potential in the first storage unit 91, is electrically connected to the first conductive path 81. The terminal on the low potential side, which is the terminal having the smallest potential in the first storage unit 91, is electrically connected to the ground 83 and is maintained at a predetermined ground potential (0V). The output voltage of the first power storage unit 91 is applied to the first conductive path 81. In this embodiment, the voltage means the magnitude of the potential with respect to the potential of the ground 83.

The second power storage unit 92 is composed of a known battery such as a lead battery. The second power storage unit 92 is not limited to the lead battery, and may be another type of battery configured to be chargeable / dischargeable. The terminal on the high potential side, which is the terminal having the highest potential in the second storage unit 92, is electrically connected to the second conductive path 82. The terminal on the low potential side, which is the terminal having the smallest potential in the second storage unit 92, is electrically connected to the ground 83 and is maintained at a predetermined ground potential (0V). The output voltage of the second power storage unit 92 is applied to the second conductive path 82. The output voltage of the second power storage unit 92 when fully charged is smaller than the output voltage of the first power storage unit 91 when fully charged.

An in-vehicle load may be electrically connected to the first conductive path 81 on the high voltage side so that DC power is supplied via the first conductive path 81. An in-vehicle load may be electrically connected to the second conductive path 82 on the low voltage side so that DC power is supplied via the second conductive path 82.

The in-vehicle power supply device 1 is, for example, an in-vehicle step-down DCDC converter, and performs a step-down operation of stepping down the DC voltage applied to the first conductive path 81 and applying the step-down operation to the second conductive path 82. The in-vehicle power supply device 1 includes a voltage conversion unit 10, a voltage detection unit 22, a current detection unit 24, and a control unit 30.

The voltage conversion unit 10 includes a first switching element 11, a second switching element 12, an inductor 14, and capacitors 15 and 16. The first switching element 11 and the second switching element 12 are connected in series between the first conductive path 81 and the reference conductive path 73 to form a half-bridge circuit. The first switching element 11 and the second switching element 12 are, for example, semiconductor switching elements, and more specifically, N-channel MOSFETs (metal-oxide-semiconductor field-effect transistors). The first switching element 11 and the second switching element 12 operate on and off in response to an on / off signal. The first switching element 11 corresponds to an example of a "switching element". An on / off signal in which the on-time Hon and the period T are set is given to the gate of the first switching element 11. The on / off signal becomes an on signal at the start of the period T, for example, and becomes an off signal when the specified on time Hon elapses. When the on-time Hon is 0, the off signal is obtained from the start of the cycle T. An on / off signal complementary to the on / off signal given to the first switching element 11 is given to the gate of the second switching element 12. When the first switching element 11 and the second switching element 12 are switched, a dead time is set in which both the first switching element 11 and the second switching element 12 are turned off. The voltage conversion unit 10 performs a step-down operation of stepping down the voltage applied to the first conductive path 81 and outputting it to the second conductive path 82 by the on-off operation of the first switching element 11 in response to the on / off signal.

The drain of the first switching element 11 is electrically connected to the first conductive path 81. The source of the first switching element 11 is electrically connected to the drain of the second switching element 12 and one end of the inductor 14. The source of the second switching element 12 is electrically connected to the reference conductive path 73. The other end of the inductor 14 is electrically connected to the second conductive path 82. One end of the capacitor 15 is electrically connected to the first conductive path 81, and the other end of the capacitor 15 is electrically connected to the reference conductive path 73. One end of the capacitor 16 is electrically connected to the second conductive path 82, and the other end of the capacitor 16 is electrically connected to the reference conductive path 73.

The voltage detection unit 22 is configured as, for example, a known voltage detection circuit. The voltage detection unit 22 detects the voltage of the second conductive path 82 and outputs a signal corresponding to the voltage of the second conductive path 82. The signal corresponding to the voltage of the second conductive path 82 is input to the control unit 30.

The current detection unit 24 has, for example, a resistor and a differential amplifier. The current detection unit 24 detects the current of the second conductive path 82 and outputs a signal corresponding to the current of the second conductive path 82. The signal corresponding to the current of the second conductive path 82 is input to the control unit 30.

The control unit 30 is configured as, for example, a microcomputer, and includes a CPU, ROM, RAM, non-volatile memory, an oscillation circuit, and the like.

The control unit 30 controls the voltage conversion unit 10. The control unit 30 gives an on / off signal to the first switching element 11 and the second switching element 12, so that the voltage conversion unit 10 performs a step-down operation by a synchronous rectification method. The control unit 30 performs feedback control so that the voltage of the second conductive path 82 approaches the target voltage value when the step-down operation is performed. The feedback control is, for example, PI control, PID control, and the like. The target voltage may be a value set by the control unit 30 or a value instructed by an external device such as an external ECU (Electronic Control Unit).

The control unit 30 has a calculation unit 32 and a signal generation unit 34. The arithmetic unit 32 determines the period T of the on / off signal and the on time Hon. The signal generation unit 34 generates an on / off signal in the period T and the on-time Hon determined by the calculation unit 32. The calculation unit 32 calculates the duty target value Dtg by feedback calculation based on the output voltage and the target voltage, determines the on-time Hon based on the duty target value Dtg and the reference period Ts, and determines the duty target value Dtg and the on-time Hon. The period T is determined based on.

The calculation unit 32 can select the period T with a predetermined period resolution Rt, and when the period T is determined based on the duty target value Dtg and the on-time Hon, a plurality of selectable period candidate values Ct A value having a duty close to the duty target value Dtg is selected as the period T. The calculation unit 32 can select the on-time Hon with a predetermined on-time resolution Ron, and is obtained by multiplying the duty target value Dtg by the reference period Ts from the selectable on-time candidate values Con. A value close to the multiplication value (Dtg × Ts) is selected as the on-time Hon.

[Signal generation processing]
The following description relates to the signal generation processing performed by the control unit 30. The processing of steps S101 to S108 is performed by, for example, the arithmetic unit 32, and the processing of steps S109 to S111 is performed, for example, by the signal generation unit 34.

When the start condition is satisfied, the control unit 30 performs the signal generation process illustrated in FIG. The start condition is, for example, that the vehicle start switch (for example, the ignition switch) is turned on. The control unit 30 can grasp the on / off state of the start switch by receiving, for example, an on / off signal indicating the on / off state of the start switch from an external device.

When the signal generation process is started, the control unit 30 specifies the output voltage of the voltage conversion unit 10, that is, the voltage of the second conductive path 82 (step S101). After specifying the output voltage, the control unit 30 calculates the deviation between the specified output voltage and the target voltage. After calculating the deviation, the control unit 30 performs a known feedback calculation such as a PID calculation or a PI calculation based on the calculated deviation to set the duty target value Dtg of the on / off signal so that the output voltage approaches the target voltage. Calculate (step S102).

After calculating the duty target value Dtg, the control unit 30 determines the on-time Hon based on the duty target value Dtg and the reference period Ts (step S103). More specifically, the control unit 30 can select the on-time Hon with a predetermined on-time resolution Ron, and has a reference cycle with respect to the duty target value Dtg from the selectable on-time candidate values Con. A value close to the multiplication value (Dtg × Ts) obtained by multiplying by Ts is selected as the on-time Hon. In the present embodiment, the control unit 30 selects the value that is Dtg × Ts or less and is closest to Dtg × Ts from the selectable on-time candidate values Con as the on-time Hon. More specifically, the control unit 30 selects the maximum value among the values that are the on-time candidate value Con and are Dtg × Ts or less as the on-time Hon. The on-time resolution Ron is the clock period Tc of the microcomputer. The on-time candidate value Con is Tc × N. N is 0 and a positive integer. The reference cycle Ts is a predetermined value that serves as a reference for the switching cycle, and is stored in advance in the control unit 30.

After determining the on-time Hon, the control unit 30 determines the period T by the processing of steps S104 to S108. More specifically, the control unit 30 can select the period T with a predetermined periodic resolution Rt, and when determining the period T based on the duty target value Dtg and the on-time Hon, a plurality of selectable periods T can be selected. A value having a duty close to the duty target value Dtg is selected as the cycle T from the cycle candidate values Ct of. As a result, the control unit 30 can fine-tune the period T so that the duty approaches the duty target value Dtg after determining the on-time Hon. In the present embodiment, the control unit 30 selects, as the cycle T, a value having a duty target value Dtg or more and closest to the duty target value Dtg from a plurality of selectable cycle candidate values Ct. More specifically, the control unit 30 selects a value having the minimum duty at the duty target value Dtg or more from the plurality of selectable cycle candidate values Ct as the cycle T. The periodic resolution Rt is the clock period Tc of the microcomputer. The cycle candidate value Ct is Tc × M. M is a positive integer.

After determining the on-time Hon, the control unit 30 calculates the reference cycle Ts as the temporary cycle Ttmp (step S104) and Hon / Ttpp as the temporary duty Dtmp (step S105). Then, the control unit 30 determines whether or not the temporary duty Dtmp is equal to or greater than the duty target value Dtg (step S106). When the temporary duty Dtmp is not equal to or more than the duty target value Dtg (No in step S106), the control unit 30 sets a new temporary cycle Ttmp as a value obtained by subtracting the periodic resolution Rt from the current temporary cycle Ttmp (step S107). ). Then, the control unit 30 returns to the process of step S105, and repeats the processes of steps S105 to S107 until the temporary duty Dtpp becomes the duty target value Dtg or more. When the temporary duty Dtmp is equal to or greater than the duty target value Dtg (Yes in step S106), the control unit 30 determines the current temporary cycle Ttmp as the cycle T (step S108).

After determining the period T, the control unit 30 determines whether or not the on / off signal is being output (step S109). When the control unit 30 is not outputting the on / off signal (No in step S109), the signal generation unit 34 outputs the on / off signal in the on-time Hon determined in step S103 and the period T determined in step S108. Generate and output (step S111). After that, the control unit 30 returns to the process of step S101.

When the on / off signal is being output (Yes in step S109), the control unit 30 determines whether or not the period T of the on / off signal being output has elapsed (step S110). When the cycle T of the on / off signal being output has not elapsed (No in step S110), the control unit 30 returns to the process of step S110. That is, the control unit 30 is in a standby state until the cycle T of the on / off signal being output elapses. When the cycle T of the on / off signal being output elapses (Yes in step S110), the signal generation unit 34 generates an on / off signal with the on-time Hon determined in step S103 and the cycle T determined in step S108. And output (step S111).

In this way, the control unit 30 determines the period T and the on-time Hon by the processing of steps S101 to S111, and generates and outputs the on-off signal in the determined period T and the on-time Hon. Then, the control unit 30 determines the next cycle T and the on-time Hon during the output of the on-off signal, and when the cycle T of the on-off signal being output elapses, the control unit 30 generates an on-off signal in the next cycle T and the on-time Hon. And output. That is, the control unit 30 periodically updates the cycle T of the on / off signal and the on-time Hon by repeating the processes of steps S101 to S111.

The following description relates to a specific example of signal generation processing. In this embodiment, the clock period Tc = 12.5ns and the reference period Ts = Tc × 800 = 10μs.

After specifying the output voltage (after step S101), the control unit 30 calculates the duty target value Dtg (step S102). It is assumed that the duty target value Dtg is, for example, 26.200%. In this case, the multiplication value (Dtg × Ts) obtained by multiplying the duty target value Dtg by the reference period Ts is Tc × 209.6. The control unit 30 determines Tc × 209, which is the maximum value among the values of Tc × 209.6 or less, as the on-time Hon from the selectable on-time candidate values Con (Tc × N). In other words, the control unit 30 determines the value of Dtg × Ts / Tc rounded down to the nearest whole number as the on-time Hon.

Subsequently, the control unit 30 calculates the reference cycle Ts (Tc × 800) as the temporary cycle Ttmp (step S104) and Hon / Ttpp as the temporary duty Dtmp (step S105). The tentative duty Dtpp is Hon / Ttpp = (Tc × 209) / (Tc × 800) = 209/800 = 26.125%. Then, in step S106, the control unit 30 determines whether or not the provisional duty Dtmp is equal to or greater than the duty target value Dtg (step S106). Since the tentative duty Dtmp (26.125%) is not equal to or greater than the duty target value Dtg (26.200%), the control unit 30 subtracts the periodic resolution Rt (Tc) from the current temporary cycle Ttpp (Tc × 800). The value is set to a new temporary period Ttpp (Tc × 799) (step S107). Then, the control unit 30 calculates the temporary duty Dtmp again and determines whether or not the duty target value Dtg or more is reached (step S106). In this way, the processes of steps S105 to S107 are repeated until the temporary duty Dtmp becomes the duty target value Dtg or more. Specifically, when the tentative cycle Ttpp = Tc × 799, the tentative duty Dtpp≈26.158%, and when the tentative cycle Ttpp = Tc × 798, the tentative duty Dtpp≈26.190%, and the tentative cycle Ttpp = Tc. In the case of × 797, the provisional duty Dtpp≈26.223%. Therefore, the control unit 30 determines that the temporary duty Dtmp (26.223%) is equal to or higher than the duty target value Dtg (26.200%) when the temporary cycle Ttmp = Tc × 797. Then, the control unit 30 determines the temporary period Ttp = Tc × 797 as the period T (step S108). If the on / off signal is not being output, the control unit 30 generates an on / off signal in the determined period T (Tc × 797) and the on time Hon (Tc × 209) and outputs the on / off signal. If the on / off signal is being output, the control unit 30 generates an on / off signal with the determined cycle T (Tc × 797) and the on time Hon (Tc × 209) after the cycle T of the on / off signal being output elapses. And output.

The following description relates to the actions and effects of the present disclosure.
The vehicle-mounted power supply device 1 determines the on-time Hon based on the duty target value Dtg and the reference cycle Ts, and determines the cycle T based on the duty target value Dtg and the on-time Hon. That is, the vehicle-mounted power supply device 1 can further adjust the period T after determining the on-time Hon. Therefore, the vehicle-mounted power supply device 1 can increase the resolution of the duty of the on / off signal used for voltage conversion as compared with the PWM signal having a fixed period T.

Further, when the cycle T is determined based on the duty target value Dtg and the on-time Hon, the vehicle-mounted power supply device 1 has a duty close to the duty target value Dtg from among a plurality of selectable cycle candidate values Ct. Select the value as period T. Therefore, the vehicle-mounted power supply device 1 can generate an on / off signal having a duty closer to the duty target value Dtg as compared with the PWM signal having a fixed period T. Therefore, according to the vehicle-mounted power supply device 1, the accuracy of voltage conversion can be further improved.

Further, the arithmetic unit 32 can select the on-time Hon with the predetermined on-time resolution Ron, and the duty target value Dtg is multiplied by the reference period Ts from the selectable on-time candidate values Con. A value close to the obtained multiplication value is selected as the on-time Hon. Therefore, according to the vehicle-mounted power supply device 1, the process of determining the on-time Hon can be simplified.

<Second Embodiment>
In the signal generation process of the first embodiment, the control unit 30 is configured to select a value having Dtg × Ts or less and closest to Dtg × Ts as the on-time Hon from the selectable on-time candidate values Con. On the other hand, in the signal generation process of the second embodiment, the control unit 30 selects the value having Dtg × Ts or more and closest to Dtg × Ts from the selectable on-time candidate values Con as the on-time Hon. It differs in that.
Further, in the signal generation processing of the first embodiment, the control unit 30 sets a value having a duty that is closest to the duty target value Dtg at the duty target value Dtg or more from among a plurality of selectable cycle candidate values Ct as the cycle T. It was configured to be selected. On the other hand, in the signal generation processing of the second embodiment, the control unit 30 cycles a value having a duty that is the closest to the duty target value Dtg, which is the duty target value Dtg or less, from among the plurality of selectable cycle candidate values Ct. It differs in that it is selected as T.
In other respects, the first embodiment and the second embodiment are common. In the following description of the second embodiment, the same components as those of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

When the start condition is satisfied, the control unit 30 performs the signal generation process illustrated in FIG. When the signal generation process is started, the control unit 30 identifies the output voltage (step S101) and calculates the duty target value Dtg (step S102). Then, the control unit 30 determines the on-time Hon based on the duty target value Dtg and the reference period Ts (step S203). In the present embodiment, the control unit 30 selects a value having Dtg × Ts or more and closest to Dtg × Ts from the selectable on-time candidate values Con as the on-time Hon. More specifically, the control unit 30 selects the minimum value among the on-time candidate values Con and Dtg × Ts or more as the on-time Hon.

After determining the on-time Hon, the control unit 30 determines the period T by the processing of steps S104, S105, S206, S207, and S108. In the present embodiment, the control unit 30 selects, as the cycle T, a value having a duty that is closest to the duty target value Dtg with a duty target value Dtg or less from among a plurality of selectable cycle candidate values Ct. More specifically, the control unit 30 selects a value having the maximum duty below the duty target value Dtg from a plurality of selectable cycle candidate values Ct as the cycle T.

After determining the on-time Hon, the control unit 30 calculates the reference cycle Ts as the temporary cycle Ttmp (step S104) and Hon / Ttpp as the temporary duty Dtmp (step S105). Then, the control unit 30 determines whether or not the temporary duty Dtmp is equal to or less than the duty target value Dtg (step S206). When the temporary duty Dtmp is not equal to or less than the duty target value Dtg (No in step S206), the control unit 30 sets a value obtained by adding the periodic resolution Rt from the current temporary cycle Ttpp as a new temporary cycle Ttmp (step S207). ). Then, the control unit 30 returns to the process of step S105, and repeats the process of steps S105, S206, and S207 until the temporary duty Dtmp becomes equal to or less than the duty target value Dtg. When the temporary duty Dtmp is equal to or less than the duty target value Dtg (Yes in step S206), the control unit 30 determines the current temporary cycle Ttmp as the cycle T (step S108).

The control unit 30 determines whether or not the on / off signal is being output (step S109). When the on / off signal is not being output (No in step S109), the control unit 30 generates and outputs an on / off signal in the on-time Hon determined in step S203 and the period T determined in step S108. (Step S111). After that, the control unit 30 returns to the process of step S101.

The following description relates to a specific example of signal generation processing.
After specifying the output voltage (after step S101), the control unit 30 calculates the duty target value Dtg (step S102). It is assumed that the duty target value Dtg is, for example, 26.200%. In this case, the multiplication value (Dtg × Ts) obtained by multiplying the duty target value Dtg by the reference period Ts is Tc × 209.6. The control unit 30 determines Tc × 210, which is the minimum value among the values of Tc × 209.6 or more, as the on-time Hon from the selectable on-time candidate values Con (Tc × N). In other words, the control unit 30 determines the value of Dtg × Ts / Tc rounded up to the nearest whole number as the on-time Hon.

Subsequently, the control unit 30 calculates the reference cycle Ts (Tc × 800) as the temporary cycle Ttmp (step S104) and Hon / Ttpp as the temporary duty Dtmp (step S105). The tentative duty Dtpp is Hon / Ttpp = (Tc × 210) / (Tc × 800) = 210/800 = 26.250%. Then, in step S206, the control unit 30 determines whether or not the provisional duty Dtmp is equal to or less than the duty target value Dtg (step S206). Since the tentative duty Dtmp (26.250%) is not less than or equal to the duty target value Dtg (26.200%), the control unit 30 has added the periodic resolution Rt (Tc) from the current tentative period Ttmp (Tc × 800). The value is set to a new temporary period Ttpp (Tc × 801) (step S207). Then, the control unit 30 calculates the temporary duty Dtmp again and determines whether or not the duty target value is Dtg or less (step S206). In this way, the processes of steps S105, S206, and S207 are repeated until the temporary duty Dtmp becomes the duty target value Dtg or less. Specifically, when the tentative cycle Ttpp = Tc × 801, the tentative duty Dtpp≈26.217%, and when the tentative cycle Ttpp = Tc × 802, the tentative duty Dtpp≈26.185%. That is, the control unit 30 determines that the temporary duty Dtmp (26.185%) is equal to or less than the duty target value Dtg (26.200%) when the temporary cycle Ttpp = Tc × 802. Then, the control unit 30 determines the temporary period Ttp = Tc × 802 as the period T (step S108). If the on / off signal is not being output, the control unit 30 generates an on / off signal in the determined period T (Tc × 802) and the on time Hon (Tc × 210) and outputs the on / off signal. If the on / off signal is being output, the control unit 30 generates an on / off signal with the determined cycle T (Tc × 802) and the on time Hon (Tc × 210) after the cycle T of the on / off signal being output elapses. And output.

<Third Embodiment>
In the signal generation process of the first embodiment, the control unit 30 selects a value having a duty target value Dtg or more and the duty closest to the duty target value Dtg from a plurality of selectable cycle candidate values Ct as the cycle T. It was configured. On the other hand, in the signal generation processing of the third embodiment, the control unit 30 selects the value having the duty closest to the duty target value Dtg from the plurality of selectable cycle candidate values Ct as the cycle T. different.
In other respects, the first embodiment and the third embodiment are common. In the following description of the third embodiment, the same components as those of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

When the start condition is satisfied, the control unit 30 performs the signal generation process illustrated in FIG. The signal generation process illustrated in FIG. 4 is different from the signal generation process illustrated in FIG. 2 in that steps S120, S121, and S122 are performed instead of step S108 after step S106, and is common in other respects. When the temporary duty Dtmp becomes the duty target value Dtg or more (Yes in step S106), the control unit 30 determines whether or not the temporary duty Dtmp is closer to the duty target value Dtg than the previous temporary duty Dtmp. Is determined (step S120). The "previous temporary duty Dtpm" is a temporary duty Dtmmp before the temporary duty Dtmp is determined to be No in step S106 and the periodic resolution Rt is subtracted in step S107. Specifically, Hon / (Ttp + Rt) ).

When the provisional duty Dtpm is closer to the duty target value Dtg than the previous provisional duty Dtmp (Yes in step S120), the control unit 30 determines the provisional cycle Ttmp as the cycle T (step S121). The control unit 30 determines when the temporary duty Dtmp is not closer to the duty target value Dtg than the previous temporary duty Dtmp (No in step S120), the previous temporary cycle Ttpp is set as the cycle T (when the temporary duty Dtpm is not closer to the previous temporary duty Dtmp (No in step S120). Step S122). The "previous tentative cycle Ttpp" is a tentative cycle Ttpm before the periodic resolution Rt is subtracted in step S107 after being determined as No in step S106, and specifically, Ttp + Rt. be.

For example, as described in the first embodiment, it is assumed that the duty target value Dtg is 26.200%. When the tentative cycle Ttpp = Tc × 799, the tentative duty Dtpp ≈26.158%, when the tentative cycle Ttmmp = Tc × 798, the tentative duty Dtpp≈26.190%, and when the tentative cycle Ttpp = Tc × 797, Temporary duty Dtpp≈26.223%. In this case, the control unit 30 determines that the provisional duty Dtmp is equal to or greater than the duty target value Dtg (Yes in step S106) when the provisional cycle Ttmp = Tc × 797. The provisional duty Dtpm at this time is 26.223%, and the previous provisional duty Dtpm is 26.190%. That is, the temporary duty Dtmp (26.223%) is not closer to the duty target value Dtg (26.200%) than the previous temporary duty Dtmp (26.190%). Therefore, the control unit 30 determines the previous temporary cycle Ttpp (Tc × 798) as the cycle T. As a result, the value having the duty closest to the duty target value Dtg is determined as the cycle T from among the plurality of selectable cycle candidate values Ct.

After step S121 or step S122, the control unit 30 generates and outputs an on / off signal in the determined period T and on time Hon (step S111).

<Fourth Embodiment>
In the signal generation process of the second embodiment, the control unit 30 selects a value having a duty that is the closest to the duty target value Dtg, which is the duty target value Dtg or less, from the plurality of selectable cycle candidate values Ct as the cycle T. It was configured. On the other hand, in the signal generation process of the fourth embodiment, the control unit 30 selects the value having the duty closest to the duty target value Dtg from the plurality of selectable cycle candidate values Ct as the cycle T. different.
In other respects, the second embodiment and the fourth embodiment are common. In the following description of the fourth embodiment, the same components as those of the second embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

When the start condition is satisfied, the control unit 30 performs the signal generation process illustrated in FIG. The signal generation process illustrated in FIG. 5 is different from the signal generation process illustrated in FIG. 3 in that steps S220, S221, and S222 are performed in place of step S108 after step S206, and is common in other respects. When the temporary duty Dtmp is equal to or less than the duty target value Dtg (Yes in step S206), the control unit 30 determines whether or not the temporary duty Dtmp is closer to the duty target value Dtg than the previous temporary duty Dtmp. Is determined (step S120). The "previous temporary duty Dtmp" is a temporary duty Dtmp before the temporary duty Dtmp is determined to be No in step S206 and the periodic resolution Rt is added in step S207. Specifically, Hon / (Ttpp) -Rt).

When the provisional duty Dtpm is closer to the duty target value Dtg than the previous provisional duty Dtmp (Yes in step S220), the control unit 30 determines the provisional cycle Ttmp as the cycle T (step S221). The control unit 30 determines when the temporary duty Dtmp is not closer to the duty target value Dtg than the previous temporary duty Dtmp (No in step S220), the previous temporary cycle Ttpp is set as the cycle T (when the temporary duty Dtpm is not closer to the previous temporary duty Dtmp). Step S222). The "previous tentative cycle Ttpp" is a tentative cycle Ttmp before the temporary cycle Ttpp is determined to be No in step S206 and the periodic resolution Rt is added in step S207. That is.

For example, as described in the second embodiment, it is assumed that the duty target value Dtg is 26.200%. When the tentative cycle Ttpp = Tc × 801, the tentative duty Dtpp≈26.217%, and when the tentative cycle Ttpp = Tc × 802, the tentative duty Dtpp≈26.185%. In this case, the control unit 30 determines that the provisional duty Dtmp is equal to or greater than the duty target value Dtg (Yes in step S106) when the provisional cycle Ttmp = Tc × 802. The tentative duty Dtpm at this time is 26.185%, and the previous tentative duty Dtpm is 26.217%. That is, the temporary duty Dtmp (26.185) is not closer to the duty target value Dtg (26.200%) than the previous temporary duty Dtmp (26.217%). Therefore, the control unit 30 determines the previous temporary cycle Ttpp (Tc × 801) as the cycle T. As a result, the value having the duty closest to the duty target value Dtg is determined as the cycle T from among the plurality of selectable cycle candidate values Ct.

After step S221 or step S222, the control unit 30 generates and outputs an on / off signal in the determined period T and on time Hon (step S111).

<Other embodiments>
The present disclosure is not limited to the embodiments described above with reference to the description and drawings. For example, the features of the embodiments described above or below can be combined in any combination within a consistent range. Further, any of the features of the above-mentioned or later-described embodiments may be omitted unless it is clearly stated as essential. Further, the above-described embodiment may be modified as follows.

In each of the above embodiments, the voltage conversion unit is a step-down DCDC converter, but it may be a step-up DCDC converter or a step-down DCDC converter. Further, in each of the above embodiments, the voltage conversion unit is a non-isolated DCDC converter, but an isolated DCDC converter may be used. Further, in each of the above embodiments, the voltage conversion unit is configured to perform voltage conversion by the synchronous rectification method, but may be configured to perform voltage conversion by the asynchronous rectification method. That is, the voltage conversion unit may have a configuration having a diode instead of the second switching element 12.

In each of the above embodiments, the control unit is mainly composed of a microcomputer, but it may be realized by a plurality of hardware circuits other than the microcomputer.

It should be noted that the embodiments disclosed this time are exemplary in all respects and are not restrictive. The scope of the present invention is not limited to the embodiments disclosed here, but includes all modifications within the scope indicated by the claims or within the scope equivalent to the claims. Is intended.

1: In-vehicle power supply device 10: Voltage conversion unit 11: First switching element (switching element)
12: Second switching element 14: Inductor 15: Capacitor 16: Capacitor 22: Voltage detection unit 24: Current detection unit 30: Control unit 32: Calculation unit 34: Signal generation unit 73: Reference conductive path 81: First conductive path 82 : 2nd conductive path 83: Ground 91: 1st power storage unit 92: 2nd power storage unit 100: In-vehicle power supply system Con: On-time candidate value Ct: Cycle candidate value Dtg: Duty target value Dtmp: Temporary duty Hon: On-time Ron: On-time resolution Rt: Periodic resolution T: Period Tc: Clock period Ts: Reference period Ttpp: Temporary period

Claims (3)

It has a switching element that operates on and off in response to an on / off signal with an on-time and period set, and boosts the voltage applied to the first conductive path by the on / off operation of the switching element in response to the on / off signal. Or a voltage converter that steps down and outputs to the second conductive path,
An arithmetic unit that determines the period and on-time of the on / off signal, and
A signal generation unit that generates the on / off signal in the cycle and the on time determined by the calculation unit, and
Have,
The calculation unit calculates a duty target value by a feedback calculation based on an output voltage and a target voltage, determines the on-time based on the duty target value and a reference period, and sets the duty target value and the on-time. An in-vehicle power supply device that determines the cycle based on the above. The calculation unit can select the cycle with a predetermined cycle resolution, and when determining the cycle based on the duty target value and the on-time, the cycle candidate value can be selected from a plurality of selectable cycle candidate values. The vehicle-mounted power supply device according to claim 1, wherein a value having a duty close to the duty target value is selected as the cycle. The calculation unit can select the on-time with a predetermined on-time resolution, and is a product obtained by multiplying the duty target value by the reference period from the selectable on-time candidate values. The vehicle-mounted power supply device according to claim 1 or 2, wherein a value close to is selected as the on-time.

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