JP2022171320A - Backup power supply, control method and control program - Google Patents

Abstract

To suppress the number of components.SOLUTION: A backup power supply includes: an electric double layer capacitor; a first switching element; a coil, one end of which is connected to one end of the first switching element and the other end of which is connected to one end of the electric double layer capacitor; a second switching element, one end of which is connected to the one end of the first switching element; and a control part which, when an input voltage is equal to or more than a first set voltage, performs a control in a first mode to charge the electric double layer capacitor by allowing the first switching element to perform switching operation, and when the input voltage is less than the first set voltage, which performs a control in a second mode to discharge the electric double layer capacitor by allowing the second switching element to perform switching operation. The control part allows the second switching element to perform switching operation, as a synchronous rectification element, in the first mode, and allows the first switching element to perform switching operation, as a synchronous rectification element, in the second mode.SELECTED DRAWING: Figure 1

Description

The present invention relates to a backup power supply device, control method and control program.

A vehicle is equipped with various devices that operate using the power of a battery (for example, an auxiliary battery). Patent Literature 1 describes a backup power supply device for operating the above equipment even when the battery cannot output electric power due to a traffic accident or the like.

In the backup power supply device described in Patent Literature 1, the booster circuit and the step-down circuit share a coil. That is, the step-up circuit and the step-down circuit constitute a step-up/step-down circuit.

Japanese Patent No. 6643566

The backup power supply device described in Patent Literature 1 includes an output rectifying element connected with the forward direction from the booster circuit to the terminal section as a current output path from the electric double layer capacitor to the terminal section. However, it is desirable to reduce the number of parts.

An object of the present invention is to provide a backup power supply device, a control method, and a control program that can reduce the number of parts.

A backup power supply device according to one aspect of the present invention includes:
an input terminal, an output terminal, a connection point electrically connected to the output terminal, and an input rectifying element having an anode electrically connected to the input terminal and a cathode electrically connected to the connection point. a terminal portion having a
an electric double layer capacitor having one end electrically connected to a reference potential;
a first switching element having one end electrically connected to the connection point;
a coil having one end electrically connected to the other end of the first switching element and the other end electrically connected to the other end of the electric double layer capacitor;
a second switching element having one end electrically connected to the other end of the first switching element and one end of the coil, and having the other end electrically connected to a reference potential;
When the input voltage input to the input terminal is equal to or higher than a predetermined first set voltage, the first switching element is switched on based on the current flowing through the first switching element and the charging voltage of the electric double layer capacitor. When the switching operation is performed to operate the first switching element and the coil as a step-down circuit to charge the electric double layer capacitor in a first mode, and the input voltage is less than the first set voltage. and switching the second switching element based on the current flowing through the second switching element and the output voltage output from the output terminal, thereby operating the second switching element and the coil as a booster circuit. a control unit that controls a second mode for discharging the electric double layer capacitor;
with
The control unit
In the first mode, the second switching element is switched as a synchronous rectification element of the step-down circuit, and in the second mode, the first switching element is switched as a synchronous rectification element of the step-up circuit.
It is characterized by

In the backup power supply,
The control unit
The second switching element is turned off at the timing when the current flowing through the second switching element becomes zero or reverses in the first mode, and the current flowing through the first switching element becomes zero in the second mode. turning off the first switching element at the timing of becoming or reversing
It is characterized by

In the backup power supply,
The control unit
making the switching frequency of the second mode higher than the switching frequency of the first mode;
It is characterized by

In the backup power supply,
The control unit
a first error amplifier for detecting an error between a charging voltage of the electric double layer capacitor and a target charging voltage of the electric double layer capacitor;
a second error amplifier that detects an error between the output voltage and a target voltage of the output voltage;
has
In the first mode, the first error amplifier is used to control the charging voltage of the electric double layer capacitor, and in the second mode, the second error amplifier is used to control the output voltage.
It is characterized by

In the backup power supply,
The control unit
In the first mode, when the charging voltage of the electric double layer capacitor reaches or exceeds a predetermined second set voltage, the switching operations of the first switching element and the second switching element are stopped, and the switching operation of the second switching element is stopped. In 2 modes, an overvoltage protection circuit that stops switching operations of the first switching element and the second switching element when the output voltage is equal to or higher than a predetermined third set voltage,
It is characterized by

In the backup power supply,
The control unit
a sawtooth wave generation circuit for generating a sawtooth wave that determines switching frequencies of the first switching element and the second switching element;
Adding current information of a current flowing through the first switching element to the sawtooth wave in the first mode, and adding current information of a current flowing through the second switching element to the sawtooth wave in the second mode. to perform current mode control,
It is characterized by

In the backup power supply,
The control unit
switching between the first mode and the second mode is performed at the start of a switching cycle;
It is characterized by

A control method according to one aspect of the present invention includes:
an input terminal, an output terminal, a node electrically connected to the output terminal, and an input rectifying element having an anode electrically connected to the input terminal and a cathode electrically connected to the node. a terminal portion, an electric double layer capacitor having one end electrically connected to a reference potential, a first switching element having one end electrically connected to the connection point, and one end connected to the other end of the first switching element. a coil electrically connected and having the other end electrically connected to the other end of the electric double layer capacitor; one end electrically connected to the other end of the first switching element and one end of the coil; A control method for a backup power supply device comprising: a second switching element having an end electrically connected to a reference potential;
When the input voltage input to the input terminal is equal to or higher than a predetermined first set voltage, the first switching element is switched on based on the current flowing through the first switching element and the charging voltage of the electric double layer capacitor. When the switching operation is performed to operate the first switching element and the coil as a step-down circuit to charge the electric double layer capacitor in a first mode, and the input voltage is less than the first set voltage. and switching the second switching element based on the current flowing through the second switching element and the output voltage output from the output terminal, thereby operating the second switching element and the coil as a booster circuit. to discharge the electric double layer capacitor, performing control in the second mode,
In the first mode, the second switching element is switched as a synchronous rectification element of the step-down circuit, and in the second mode, the first switching element is switched as a synchronous rectification element of the step-up circuit.
It is characterized by

A control program according to one aspect of the present invention comprises
an input terminal, an output terminal, a node electrically connected to the output terminal, and an input rectifying element having an anode electrically connected to the input terminal and a cathode electrically connected to the node. a terminal portion, an electric double layer capacitor having one end electrically connected to a reference potential, a first switching element having one end electrically connected to the connection point, and one end connected to the other end of the first switching element. a coil electrically connected and having the other end electrically connected to the other end of the electric double layer capacitor; one end electrically connected to the other end of the first switching element and one end of the coil; A control program for a backup power supply device comprising: a second switching element having an end electrically connected to a reference potential;
When the input voltage input to the input terminal is equal to or higher than a predetermined first set voltage, the first switching element is switched on based on the current flowing through the first switching element and the charging voltage of the electric double layer capacitor. When the switching operation is performed to operate the first switching element and the coil as a step-down circuit to charge the electric double layer capacitor in a first mode, and the input voltage is less than the first set voltage. and switching the second switching element based on the current flowing through the second switching element and the output voltage output from the output terminal, thereby operating the second switching element and the coil as a booster circuit. to discharge the electric double layer capacitor, performing control in the second mode,
In the first mode, the second switching element is switched as a synchronous rectification element of the step-down circuit, and in the second mode, the first switching element is switched as a synchronous rectification element of the step-up circuit.
Let the processor do that.

A backup power supply device, a control method, and a control program according to one aspect of the present invention have the effect of reducing the number of parts.

FIG. 1 is a diagram showing the configuration of a backup power supply device according to an embodiment. FIG. 2 is a diagram showing a circuit configuration of a battery voltage drop monitoring section and a mode switching timing adjustment section of the backup power supply device according to the embodiment. FIG. 3 is a diagram showing a circuit configuration of a switching frequency setting section of the backup power supply device according to the embodiment. FIG. 4 is a diagram showing an example of a sawtooth wave signal and a periodic pulse signal of the backup power supply device according to the embodiment. FIG. 5 is a diagram showing a circuit configuration of a switching current detector of the backup power supply device according to the embodiment. FIG. 6 is a diagram showing a circuit configuration of a current information detection section of the backup power supply device according to the embodiment. FIG. 7 is a diagram showing a circuit configuration of an overvoltage detector of the backup power supply device according to the embodiment. FIG. 8 is a diagram showing the circuit configuration of the output voltage error detection section of the backup power supply device according to the embodiment. FIG. 9 is a diagram showing an example of a sawtooth wave signal, a current information signal, an error signal, and a main switching control signal of the backup power supply device according to the embodiment. FIG. 10 is a diagram showing the circuit configuration of the drive selection unit of the backup power supply device according to the embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a backup power supply device, a control method, and a control program according to the present invention will be described in detail below with reference to the drawings. It should be noted that the present invention is not limited by this embodiment.

<Embodiment>
FIG. 1 is a diagram showing the configuration of a backup power supply device according to an embodiment.

When the voltage V _IN of the battery 2 is equal to or higher than a predetermined input voltage threshold, the backup power supply device 1 uses power supplied from the battery 2 via the input terminals 1a and 1b to 3 to charge.

The input voltage threshold corresponds to an example of the "first set voltage" of the present disclosure.

When the voltage _VIN of the battery 2 is less than the input voltage threshold, the backup power supply 1 uses the electric power charged in the electric double layer capacitor 3 to output a DC voltage from the output terminal 1c. The power output from the output terminal 1c is supplied to an electronic device (not shown).

The battery 2 is exemplified by an auxiliary battery mounted on a vehicle, but the present disclosure is not limited to this. The voltage V _IN is exemplified as 12V or 24V, but the present disclosure is not limited to this. The input voltage threshold is exemplified as 9V, but the present disclosure is not limited to this.

The backup power supply device 1 includes resistors R ₁ to R ₁₂ , a capacitor C ₁ , an electric double layer capacitor 3 , a step-up/down circuit 4 , a terminal section 5 and a control section 10 . The step-up/down circuit 4 includes switching elements _Q1 and _Q2 and _a coil L1. The terminal section 5 includes input terminals 1a and _1b , an output terminal 1c, and a diode D1.

The input terminal 1a is electrically connected to the high potential end of the battery 2 . The input terminal 1b is electrically connected to the low potential end of the battery 2 . A low potential end of the battery 2 is electrically connected to a reference potential. The reference potential is exemplified by a ground potential, but the present disclosure is not limited to this.

_One end of the resistor R1 is electrically connected to the input terminal 1a on the high potential side. The other end of resistor R1 is electrically connected to _one end of resistor _R2 . The other end of the resistor _R2 is electrically connected to the input terminal 1b on the low potential side. The resistors R ₁ and R ₂ output a voltage V ₁ obtained by dividing the voltage _VIN to the control section 10 . That is, V ₁ = _VIN /(R ₁ +R ₂ )×R ₂ .

_The anode of diode D1 is electrically connected to input terminal 1a. _The cathode of diode D1 is electrically connected to node _N1 .

_The node N1 corresponds to an example of the "connection point" of the present disclosure.

Diode D1 passes current from battery ₂ to node _N1 when voltage _VIN is higher _than voltage _VN1 at node N1. Diode D1 blocks current from node _N1 to battery ₂ when voltage _VIN is lower _than voltage VN1.

_One end of capacitor C1 is electrically connected to node _N1 . The _other end of the capacitor C1 is electrically connected to the input terminal 1b. Capacitor C1 stabilizes and smoothes _{voltage VN1 .}

When the backup power supply 1 charges the electric double layer capacitor 3, the voltage _VN1 is the input voltage, that is, the voltage _VIN . When the backup power supply 1 discharges the electric double layer capacitor 3, the voltage _VN1 is the output voltage.

_One end of resistor R3 is electrically connected to node _N1 . The other end of resistor _R3 is electrically connected to one end of resistor _R4 . The other end of the resistor _R4 is electrically connected to the input terminal 1b. The resistor R3 and the resistor _{R4 output} to the control unit ₁₀ a _voltage V2 obtained by dividing the voltage VN1. That is, V2 _{= VN1} / ₍ R3+ _R4 )* _R4 .

When the backup power supply device 1 charges the electric _double layer capacitor 3, the voltage V2 is proportional to the input voltage, that is, the voltage V _IN (=voltage V _N1 ). When the backup power supply 1 discharges the electric _double layer capacitor 3, the voltage V2 is proportional to the output _voltage , that is, the voltage VN1.

_One end of resistor R5 is electrically connected to node _N1 . The other end of resistor _R5 is electrically connected to the drain of switching element _Q1 . A voltage V ₆ at one end of the resistor R ₅ and a voltage V ₇ at the other end of the resistor R ₅ are input to the controller 10 .

The source of switching element _Q1 is electrically connected to _one end of coil L1. A switching control signal S1 is input from the control unit ₁₀ to the gate of the switching element _Q1 through the resistor _R6 .

The switching element Q1 corresponds to an example of the " _first switching element" of the present disclosure.

Note that in the present disclosure, each switching element is a MOSFET, but the present disclosure is not limited to this. Each switching element may be a silicon power device, a GaN power device, a SiC power device, an IGBT (Insulated Gate Bipolar Transistor), or the like.

Each switching element has a parasitic diode (body diode). A parasitic diode is a pn junction between the back gate and the source and drain of a MOSFET. A parasitic diode can be used as a freewheeling diode to escape the transient back electromotive force when the transistor is turned off.

The control unit 10 can detect the current flowing between the drain and source of the switching element _Q1 based _on the voltage across the resistor R5, that is, the difference between the voltages _V6 and _V7 .

In the embodiment, the backup power supply device ₁ includes the resistor R5, but the present disclosure is not limited to this. The control unit 10 may detect the current flowing between the drain and source of the switching element _Q1 based on the voltage between the drain and source of the switching element _Q1 . In this case, the backup power supply device ₁ does not have to include the resistor R5. However, the ON resistance of the switching element _Q1 changes more with temperature than the resistance _R5 . Therefore, the backup power supply device ₁ should be provided with the resistor R5 when high accuracy is required, and should use the ON resistance of the switching element _Q1 when high accuracy is not required.

The drain of switching element _Q2 is electrically connected to the source of switching element _Q1 and _one end of coil L1. The source of switching element _Q2 is electrically connected to one end of resistor _R8 . The other end of resistor _R8 is electrically connected to input terminal 1b. A switching control signal S2 is input from the control unit ₁₀ to the gate of the switching element _Q2 through the resistor _R7 .

The switching element Q2 corresponds to an example of the " _second switching element" of the present disclosure.

One end of resistor _R9 is electrically connected to the source of switching element _Q2 and one end of resistor _R8 . A voltage _V4 at the source of the switching element _Q2 and one end of the resistor _R8 is input to the control section ₁₀ via the resistor R9.

One end of resistor _R10 is electrically connected to the source of switching element _Q2 and one end of resistor _R8 . A voltage _V5 at the source of the switching element _Q2 and one end of the resistor R8 is input to the control unit ₁₀ via the resistor _R10 .

The control unit 10 can detect the current flowing between the drain and source of the switching element _Q2 based _on the voltage across the resistor R8, that is, the voltage _V4 or the voltage _V5 .

In addition, although the backup power supply device 1 is provided with the resistor R8 _in the embodiment, the present disclosure is not limited to this. The control unit 10 may detect the current flowing between the drain and source of the switching element _Q2 based on the voltage between the drain and source of the switching element _Q2 . In this case, the backup power supply device ₁ does not have to include the resistor R8. However, the ON resistance of the switching element _Q2 changes more with temperature than the resistance _R8 . Therefore, the backup power supply device ₁ should be provided with the resistor R8 when high accuracy is required, and should use the ON resistance of the switching element _Q2 when high accuracy is not required.

The other end of the coil L1 is electrically connected to _one end (high potential side end) of the electric double layer capacitor 3 . The other end (low potential side end) of the electric double layer capacitor 3 is electrically connected to the input terminal 1b.

One end of the resistor R ₁₁ is electrically connected to one end of the electric double layer capacitor 3 . The other end of resistor _R11 is electrically connected to one end of resistor _R12 . The other end of resistor _R12 is electrically connected to the other end of electric double layer capacitor 3 . A resistor R ₁₁ and a resistor R ₁₂ output a voltage V 3 obtained by dividing the voltage V _EDLC of the electric double layer capacitor ₃ to the control unit 10 . That is, V ₃ =V _EDLC ÷(R ₁₁ +R ₁₂ )×R ₁₂ .

The control unit 10 controls the step-up/down circuit ₄ based _on the voltages V1 to V7.

In the mode for charging the electric double layer capacitor 3 (hereinafter referred to as “first mode”), the control unit 10 controls the step-up/down circuit 4 so that the voltage _VIN is stepped down and output to the electric double layer capacitor 3 . to control. In the first mode, the input voltage of the buck-boost circuit 4 is the voltage _VIN and the output voltage is the voltage _VEDLC .

In the first mode, the control unit 10 operates the switching element _Q1 and the coil L1 as _a step-down circuit. In the first mode, the control unit 10 operates the switching element _Q1 as the main switching element and the switching element _Q2 as the synchronous rectification element.

In the mode of discharging the electric double layer capacitor 3 (hereinafter referred to as the “second mode”), the control unit 10 controls the step-up/step-down circuit 4 so as to step up the voltage _VEDLC and output it to the output terminal 1c. do. In the second mode, the input voltage of the buck-boost circuit 4 is the voltage _VEDLC and the output voltage is the voltage _VN1 .

In the second mode, the control unit 10 operates the switching element _Q2 and the coil L1 as _a booster circuit. Further, in the second mode, the control unit 10 operates the switching element _Q2 as a main switching element and operates the switching element _Q1 as a synchronous rectification element.

The control unit 10 includes a battery voltage drop monitoring unit 11, a mode switching timing adjustment unit 12, a switching frequency setting unit 13, a switching current detection unit 14, a current information detection unit 15, an overvoltage detection unit 16, and an output voltage It includes an error detector 17, an on/off controller 18, a drive selector 19, a first level shifter 20, a _second level shifter 21, and gate drive circuits _B1 and B2.

The battery voltage drop monitoring unit 11 monitors whether the voltage V _IN of the battery ₂ has dropped below the input voltage threshold based on the voltage V1. The mode switching timing adjusting section 12 switches the mode signal S _MODE representing the first mode or the second mode at the leading timing of the switching cycle based on the output signal from the battery voltage drop monitoring section 11 .

FIG. 2 is a diagram showing a circuit configuration of a battery voltage drop monitoring section and a mode switching timing adjustment section of the backup power supply device according to the embodiment.

Battery voltage drop monitoring unit 11 includes a comparator 31 and a constant voltage source 32 . The voltage of the constant voltage source 32 is input to the non-inverting input terminal (+terminal) of the comparator 31 . The voltage of the constant voltage source 32 is a voltage according to the input voltage threshold. Specifically, the voltage of the constant voltage source 32 is ((input voltage threshold)/(R ₁ +R ₂ )×R ₂ ). A voltage V ₁ is input to the inverting input terminal (− terminal) of the comparator 31 .

The comparator 31 outputs a low level signal when the voltage V1 is _equal to or higher than the voltage of the constant voltage source 32 . That is, the comparator 31 outputs a low level signal when the voltage _VIN of the battery 2 is equal to or higher than the input voltage threshold.

On the other hand, when the voltage V1 is _less than the voltage of the constant voltage source 32, the comparator 31 outputs a high level signal. That is, the comparator 31 outputs a high level signal when the voltage _VIN of the battery 2 is less than the input voltage threshold.

The mode switching timing adjustment section 12 includes a D-type flip-flop 41 and a one-shot circuit 42 .

An output signal of the comparator 31 is input to a D terminal (signal input terminal) of the D flip-flop 41 .

The one-shot circuit 42 outputs a one-shot pulse to the T terminal (trigger input terminal) of the D-type flip-flop 41 at the timing when a periodic pulse signal S _OSC (described later) representing the switching period changes from low level to high level. .

The D-type flip-flop 41 takes in the output signal of the comparator 31 at the timing when the one-shot pulse input from the one-shot circuit 42 changes from low level to high level. The D-type flip-flop 41 outputs a mode signal S _MODE representing a mode from an inverted output terminal (Q-bar terminal).

The mode signal S _MODE indicates the first mode (charging mode) when it is at high level, and indicates the second mode (discharging mode) when it is at low level.

Referring to FIG. 1 again, the switching frequency setting unit 13 outputs a periodic pulse signal S _OSC representing the switching frequency based on the mode signal S _MODE .

FIG. 3 is a diagram showing a circuit configuration of a switching frequency setting section of the backup power supply device according to the embodiment.

The switching frequency setting unit 13 includes NOT gate circuits (inverting circuits) 51 and 61, constant current sources 52, 53, 56 and 57, transfer gate circuits 54, 55, 58, 64 and 65, a capacitor 59, and a comparator. 60 and constant voltage sources 62 and 63 .

The switching frequency setting unit 13 corresponds to an example of the "sawtooth wave generating circuit" of the present disclosure.

The NOT gate circuit 51 inverts the mode signal S _MODE and outputs it to the transfer gate circuits 54 and 58 . Therefore, the transfer gate circuits 54 and 58 are turned off when the mode signal S _MODE is at high level (first mode), and turned on when the mode signal S _MODE is at low level (second mode).

The low potential end of capacitor 59 is electrically connected to a reference potential.

The constant current source 52 is electrically connected between the power supply potential VDD and the high potential end of the capacitor 59 .

One end of the constant current source 53 is electrically connected to the power supply potential VDD. The other end of constant current source 53 is electrically connected to the high potential end of capacitor 59 via transfer gate circuit 54 .

When the mode signal S _MODE is at high level (first mode), the transfer gate circuit 54 is turned off. Therefore, capacitor 59 is charged by constant current source 52 only. When the mode signal S _MODE is at low level (second mode), the transfer gate circuit 54 is turned on. Capacitor 59 is therefore charged by both constant current sources 52 and 53 . That is, since the charging current of the capacitor 59 changes according to the signal value of the mode signal S _MODE , the voltage rising speed changes.

The voltage at the high end of capacitor 59 is sawtooth signal _SSAW .

The inverting input terminal (-terminal) of the comparator 60 is electrically connected to the high potential end of the capacitor 59 . A non-inverting input terminal (+ terminal) of the comparator 60 is electrically connected to the constant voltage source 62 via the transfer gate circuit 64 and electrically connected to the constant voltage source 63 via the transfer gate circuit 65 . It is connected to the.

The transfer gate circuit 64 is turned on when the output signal of the comparator 60 is at high level, and turned off when the output signal of the comparator 60 is at low level.

The NOT gate circuit 61 inverts the output signal of the comparator 60 and outputs it to the transfer gate circuits 55 and 65 . Therefore, the transfer gate circuits 55 and 65 are turned off when the output signal of the comparator 60 is at high level, and turned on when the output signal of the comparator 60 is at low level.

The comparator 60 outputs a high level signal when the voltage of the capacitor 59 is less than the reference voltage (the voltage of the constant voltage source 62 or 63). When the output signal of the comparator 60 is at high level, the transfer gate circuit 64 is turned on, so the voltage of the constant voltage source 62 is input to the non-inverting input terminal of the comparator 60 as the reference voltage.

The comparator 60 outputs a low level signal when the voltage of the capacitor 59 is equal to or higher than the reference voltage (the voltage of the constant voltage source 62 or 63). When the output signal of the comparator 60 is low level, the transfer gate circuit 65 is turned on, so that the voltage of the constant voltage source 63 is input to the non-inverting input terminal of the comparator 60 as the reference voltage.

That is, the reference voltage of the comparator 60 differs when changing from low level to high level and when the output signal changes from high level to low level.

The output signal of the comparator 60 is the periodic pulse signal _SOSC .

One end of the transfer gate circuit 55 is electrically connected to the high potential end of the capacitor 59 .

Constant current source 56 is electrically connected between the other end of transfer gate circuit 55 and the reference potential.

One end of the transfer gate circuit 58 is electrically connected to the other end of the transfer gate circuit 55 .

Constant current source 57 is electrically connected between transfer gate circuit 58 and the reference potential.

When the mode signal S _MODE is high level (first mode), the capacitor 59 is discharged only by the constant current source 56 . When the mode signal S _MODE is at low level (second mode), the transfer gate circuit 58 is turned on. Capacitor 59 is therefore discharged by both constant current sources 56 and 57 . That is, the discharge current of the capacitor 59 changes according to the signal value of the mode signal S _MODE , so the voltage drop speed changes.

In summary, the capacitor 59 is charged and discharged at a relatively slow speed when the mode signal S _MODE is at high level (first mode). Therefore, the frequencies of the sawtooth wave signal S _SAW and the periodic pulse signal S _OSC are relatively low.

On the other hand, the capacitor 59 is charged and discharged at a relatively high speed when the mode signal S _MODE is at low level (second mode). Therefore, the frequencies of the sawtooth wave signal S _SAW and the periodic pulse signal S _OSC are relatively high.

FIG. 4 is a diagram showing an example of a sawtooth wave signal and a periodic pulse signal of the backup power supply device according to the embodiment.

The sawtooth wave signal _SSAW starts rising from timing _t0 . The rising speed of sawtooth wave signal S _SAW depends on the current values of constant current sources 52 and 53 . The periodic pulse signal _SOSC becomes high level at timing _t0 .

The periodic pulse signal S _OSC becomes low level at the timing t ₁ when the sawtooth wave signal S _SAW reaches the voltage V ₁₀₀ (the voltage of the constant voltage source 62). When the periodic pulse signal S _OSC becomes low level, the reference voltage switches from the voltage V ₁₀₀ (the voltage of the constant voltage source 62) to the voltage V ₁₀₁ (the voltage of the constant voltage source 63). _The sawtooth wave signal _SSAW starts falling from timing t1. The falling speed of sawtooth wave signal S _SAW depends on the current values of constant current sources 56 and 57 .

The periodic pulse signal S _OSC becomes _high level at the timing t2 when the sawtooth wave signal S _SAW reaches the voltage _V101 . When the periodic pulse signal S _OSC becomes high level, the reference voltage switches from the voltage _V101 to the voltage _V100 . _The sawtooth wave signal _SSAW starts rising from timing t2.

Referring to FIG. 1 again, the first level shifter 20 level-shifts the voltages V ₆ and V ₇ to ground level voltages and outputs the ground level voltages to the switching current detector 14 .

Based _on the level-shifted voltages of _V6 and _V7 , the switching current detector 14 detects that the current flowing through the resistor R5, that is, the current between the drain and the source of the switching element _Q1 has reached zero or Detect when it is reversed.

Also, the switching current detector ₁₄ detects that the current flowing through the resistor R8, that is, the current between the drain and source of the switching element _Q2 has reached zero or has been reversed, based _on the voltage V4.

In the first mode, the switching current detection unit 14 outputs the inversion detection signal S _REV to the ON/OFF control unit 18 when the current flowing between the drain and source of the switching element _Q2 , which is a synchronous rectification element, reaches zero or is reversed. output to

In the second mode, the switching current detection unit 14 controls the inversion detection signal S _REV on and off when the current flowing between the drain and source of the switching element _Q1 , which is a synchronous rectification element, reaches zero or is reversed. output to the unit 18;

FIG. 5 is a diagram showing a circuit configuration of a switching current detector of the backup power supply device according to the embodiment.

The switching current detector 14 includes comparators 121 and 122 , transfer gate circuits 123 and 124 , and a NOT gate circuit 125 .

The inverting input terminal (-terminal) of the comparator 121 is electrically connected to the reference potential. The output signal of the first level shifter 20 is input to the non-inverting input terminal (+terminal) of the comparator 121 . The comparator 121 outputs a high level signal when the output signal of the first level shifter 20 is greater than zero, and outputs a low level signal when the output signal of the first level shifter 20 is less than zero. .

The inverting input terminal (-terminal) of the comparator 122 is electrically connected to the reference potential. A voltage _V4 is input to the non-inverting input terminal (+ terminal) of the comparator 122 . Comparator 122 outputs a high level signal when voltage _V4 is greater than zero and a low level signal when voltage _V4 is less than zero.

The NOT gate circuit 125 inverts the mode signal S _MODE and outputs it to the transfer gate circuit 124 .

When the mode signal S _MODE is at high level, the transfer gate circuit 123 outputs the output signal of the comparator 121 as the inverted detection signal S _REV .

When the mode signal S _MODE is at low level, the transfer gate circuit 124 outputs the output signal of the comparator 122 as the inverted detection signal S _REV .

Referring to FIG. 1 again, the second level shifter 21 level-shifts the voltages V ₆ and V ₇ to ground level voltages and outputs the ground level voltages to the current information detector 15 .

In the first mode, the current information detector 15 detects the current information of the drain-source current of the switching element _Q1 , which is the main switching element.

In the second mode, the current information detector 15 detects the current information of the drain-source current of the switching element _Q2 , which is the main switching element.

FIG. 6 is a diagram showing a circuit configuration of a current information detection section of the backup power supply device according to the embodiment.

The current information detector 15 includes a first voltage-current converter 71, diodes 72, 75 and 79, a resistor 73, a second voltage-current converter 74, a NOT gate circuit 77, and transfer gate circuits 76 and 80. , and a third voltage-to-current converter 78 .

The first voltage-current converter 71 converts the voltage of the sawtooth wave signal _SSAW into a current and outputs the current.

An anode of the diode 72 is electrically connected to the first voltage-current converter 71 . A cathode of the diode 72 is electrically connected to one end of the resistor 73 . A connection point between the cathode of the diode 72 and one end of the resistor 73 is a node _N2 . The other end of resistor 73 is electrically connected to a reference potential.

The voltage at node _N2 is the current information signal _{S_CINFO} .

The second voltage _- to-current converter ₇₄ converts the level-shifted voltages of V6 and V7 into currents and outputs the currents.

The anode of the diode 75 is electrically connected to the second voltage-current converter 74 . The cathode of diode 75 is electrically connected to node _N2 .

Transfer gate circuit 76 is electrically connected between the anode of diode 75 and the reference potential.

The NOT gate circuit 77 inverts the mode signal S _MODE and outputs it to the transfer gate circuit 76 . Therefore, the transfer gate circuit 76 is turned off when the mode signal S _MODE is at high level (first mode), and turned on when the mode signal S _MODE is at low level (second mode).

When the transfer gate circuit 76 is in the off state, the output current of the second voltage-current converter 74 flows through the diode 75 to the node _N2 . When the transfer gate circuit 76 is in the ON state, the output current of the second voltage-current converter 74 flows to the reference potential.

The third voltage _- current converter 78 converts the voltage V5 into a current and outputs the current.

An anode of the diode 79 is electrically connected to the third voltage-current converter 78 . The cathode of diode 79 is electrically connected to node _N2 .

Transfer gate circuit 80 is electrically connected between the anode of diode 79 and the reference potential.

The transfer gate circuit 80 is turned on when the mode signal S _MODE is at high level (first mode), and turned off when the mode signal S _MODE is at low level (second mode).

When the transfer gate circuit 80 is in the ON state, the output current of the third voltage-current converter 78 flows to the reference potential. When the transfer gate circuit 80 is in the off state, the output current of the third voltage-to-current converter 78 flows through the diode 79 to the node _N2 .

Summarizing the above, when the mode signal S _MODE is at high level (first mode), the output current of the first voltage _- to-current converter 71, the output current of the second voltage-to-current converter 74, The sum of flows. In other words, the current information signal _{S_CINFO} becomes a signal obtained by adding the drain-to-source current information of the switching element _Q1 , which is the main switching element, to the sawtooth wave signal _{S_SAW} .

On the other hand, when the mode signal S _MODE is at the low level (second mode), the sum of the output current of the first voltage-to-current converter 71 and the output current of the third voltage-to-current converter 78 is at the node _N2 . flow. In other words, the current information signal _{S_CINFO} becomes a signal obtained by adding the drain-to-source current information of the switching element _Q2 , which is the main switching element, to the sawtooth wave signal _{S_SAW} .

Referring to FIG. 1 again, in the first mode, the overvoltage detector 16 outputs the overvoltage detection signal S _OVP when it detects that the output voltage (voltage V _EDLC ) of the step-up/down circuit 4 is overvoltage. .

In the second mode, the overvoltage detector 16 outputs the overvoltage detection signal S _OVP when it detects that the output voltage (voltage V _N1 ) of the step-up/down circuit 4 is overvoltage.

FIG. 7 is a diagram showing a circuit configuration of an overvoltage detector of the backup power supply device according to the embodiment.

The overvoltage detector 16 includes a comparator 101 , constant voltage sources 102 and 103 , transfer gate circuits 104 , 105 , 106 and 107 and a NOT gate circuit 108 .

The comparator 101 corresponds to an example of the "overvoltage protection circuit" of the present disclosure.

The inverting input terminal (-terminal) of the comparator 101 is electrically connected to the constant voltage source 102 via the transfer gate circuit 104, and is electrically connected to the constant voltage source 103 via the transfer gate circuit 105. It is connected.

The voltage of the constant voltage source 102 is a voltage corresponding to a predetermined first overvoltage threshold, which is the overvoltage threshold of the output voltage (voltage V _EDLC ) of the step-up/down circuit 4 in the first mode. Specifically, the voltage of the constant voltage source 102 is ((first overvoltage threshold)÷(R ₁₁ +R ₁₂ )×R ₁₂ ).

The voltage of the constant voltage source 103 is a voltage corresponding to a predetermined second overvoltage threshold that is the overvoltage threshold of the output voltage (voltage V _N1 ) of the step-up/down circuit 4 in the second mode. Specifically, the voltage of the constant voltage source 103 is ((second overvoltage threshold)÷(R ₃ +R ₄ )×R ₄ ).

The first overvoltage threshold corresponds to an example of the "second set voltage" of the present disclosure. The second overvoltage threshold corresponds to an example of the "third set voltage" of the present disclosure.

NOT gate circuit 108 inverts mode signal S _MODE and outputs it to transfer gate circuits 105 and 107 .

The transfer gate circuit 104 is turned on when the mode signal S _MODE is at high level (first mode), and turned off when the mode signal S _MODE is at low level (second mode).

The transfer gate circuit 105 is turned off when the mode signal S _MODE is at high level (first mode), and turned on when the mode signal S _MODE is at low level (second mode).

A voltage _V3 is input to the non-inverting input terminal (+terminal) of the comparator 101 via the transfer gate circuit 106 . Also, the voltage V2 is input to the non _- inverting input terminal of the comparator 101 via the transfer gate circuit 107 .

The transfer gate circuit 106 is turned on when the mode signal S _MODE is at high level (first mode), and turned off when the mode signal S _MODE is at low level (second mode).

The transfer gate circuit 107 is turned off when the mode signal S _MODE is at high level (first mode), and turned on when the mode signal S _MODE is at low level (second mode).

Summarizing the above, in the first mode, the comparator 101 operates when the voltage _{V3 is equal to or higher than the voltage of the constant voltage source 102, that is, when the voltage VEDLC ,} which is the output voltage of the step-up/down circuit 4, is equal to or higher than the first overvoltage threshold. In this case, it outputs a high-level overvoltage detection signal _{S_OVP} . Further, in the _second mode, when the voltage V2 is equal to or higher than the voltage of the constant voltage source 103, that is, when the voltage VN1, which is the output _voltage of the step-up/down circuit 4, is equal to or higher than the second overvoltage threshold, the comparator 101 It outputs a high-level overvoltage detection signal _SOVP .

Referring to FIG. 1 again, in the first mode, the output voltage error detector 17 outputs an error signal S _ERR representing the error between the output voltage (voltage V _EDLC ) of the step-up/down circuit 4 and the target voltage.

In the second mode, the output voltage error detector 17 outputs an error signal S _ERR representing the error between the output voltage (voltage V _N1 ) of the step-up/down circuit 4 and the target voltage.

FIG. 8 is a diagram showing the circuit configuration of the output voltage error detection section of the backup power supply device according to the embodiment.

The output voltage error detection unit 17 includes error amplifiers (operational amplifiers) 81 and 85, constant voltage sources 82 and 86, resistors 83 and 87, capacitors 84 and 88, transfer gate circuits 89 and 90, and a NOT gate circuit 91. and including.

A voltage from a constant voltage source 82 is input to the non-inverting input terminal (+terminal) of the error amplifier 81 . The voltage of the constant voltage source 82 is a voltage corresponding to the target voltage of the output voltage (voltage V _N1 ) of the step-up/down circuit 4 in the second mode. Specifically, the voltage of the constant voltage source 82 is ((target _voltage of voltage VN1)÷(R ₃ +R ₄ )×R ₄ ).

_A voltage V2 is input to the inverting input terminal (− terminal) of the error amplifier 81 . A resistor 83 and a capacitor 84 provide negative feedback between the inverting input terminal and the output terminal of the error amplifier 81 . _The error amplifier 81 outputs a voltage corresponding to the difference voltage between the voltage of the constant voltage source 82 and the voltage V2.

A voltage from a constant voltage source 86 is input to the non-inverting input terminal (+terminal) of the error amplifier 85 . The voltage of the constant voltage source 86 is a voltage corresponding to the target voltage of the output voltage (voltage V _EDLC ) of the step-up/down circuit 4 in the first mode. Specifically, the voltage of the constant voltage source 86 is ((target voltage of voltage V _EDLC )÷(R ₁₁ +R ₁₂ )×R ₁₂ ).

A voltage _V3 is input to the inverting input terminal (− terminal) of the error amplifier 85 . A resistor 87 and a capacitor 88 provide negative feedback between the inverting input terminal and the output terminal of the error amplifier 85 . The error amplifier 85 outputs a voltage corresponding to the difference voltage between the voltage of the constant voltage source 86 and the voltage _V3 .

The NOT gate circuit 91 inverts the mode signal S _MODE and outputs it to the transfer gate circuit 89 . Therefore, the transfer gate circuit 89 is turned off when the mode signal S _MODE is at high level (first mode), and turned on when the mode signal S _MODE is at low level (second mode).

The transfer gate circuit 90 is turned on when the mode signal S _MODE is at high level (first mode), and turned off when the mode signal S _MODE is at low level (second mode).

In summary, when the mode signal S _MODE is at high level (first mode) _, the output voltage error detector 17 detects the voltage corresponding to the difference voltage between the voltage V3 and the voltage of the constant voltage source 86 as an error. Output as signal _{S_ERR} . In other words, the output voltage error detection unit 17 outputs the error signal S _ERR corresponding to the difference voltage between the voltage V _EDLC which is the output voltage of the step-up/down circuit 4 and the target voltage (for example, 3 V).

On the other hand, when the mode signal S _MODE is at the low level ( _second mode), the output voltage error detector 17 outputs a voltage corresponding to the difference voltage between the voltage V2 and the voltage of the constant voltage source 82 as the error signal S _ERR . output as That is, the output voltage error detection unit 17 outputs the error signal S _ERR corresponding to the difference voltage between the voltage VN1, which is the output _voltage of the step-up/down circuit 4, and the target voltage (for example, 12V).

Referring to FIG. 1 again, the on/off control unit 18 controls the main switching elements based on the periodic pulse signal S _OSC , the inverted detection signal S _REV , the current information signal S _CINFO , the overvoltage detection signal S _OVP and the error signal S _ERR . A main switching control signal S _SW1 for controlling the synchronous rectification and a synchronous rectification switching control signal S _SW2 for controlling the synchronous rectification element are output to the drive selection unit 19 .

In the first mode, the on/off control unit 18 controls the switching of the switching element _Q1 and turns on the switching element _Q2 during part of the period when the switching element _Q1 is off. That is, the on/off control unit 18 operates the switching element _Q1 as a main switching element and operates the switching element _Q2 as a synchronous rectification element to perform synchronous rectification control.

In the second mode, the on/off control unit 18 controls the switching of the switching element _Q2 and turns on the switching element _Q1 during a part of the period when the switching element _Q2 is off. That is, the on/off control unit 18 operates the switching element _Q2 as a main switching element and operates the switching element _Q1 as a synchronous rectification element to perform synchronous rectification control.

The on/off control unit 18 matches the frequencies of the main switching control signal S _SW1 and the synchronous rectification switching control signal S _SW2 to the frequency of the periodic pulse signal S _OSC . The frequency of the periodic pulse signal S _OSC is higher in the second mode than in the first mode. That is, the frequencies of the main switching control signal S _SW1 and the synchronous rectification switching control signal S _SW2 are higher in the second mode than in the first mode.

The on/off control unit 18 controls the main switching element and the synchronous rectification element so that the output voltage of the step-up/down circuit 4 approaches the target voltage. In the first mode, the error signal _{SERR is a signal corresponding to the difference voltage between the voltage VEDLC ,} which is the output voltage of the step-up/down circuit 4, and the target voltage. The error signal _SERR is a signal corresponding to the difference voltage between the voltage _VN1 , which is the output voltage of the step-up/down circuit 4, and the target voltage in the second mode.

The on/off control unit 18 turns off the synchronous rectification element at the timing when the inverted detection signal S _REV becomes high level. That is, in the first mode, the on/off control section 18 turns off the switching element _Q2 , which is a synchronous rectification element, at the timing when the inversion detection signal _{S_REV} becomes high level. In the second mode, the on/off control section 18 turns off the switching element _Q1 , which is a synchronous rectification element, at the timing when the inversion detection signal _{S_REV} becomes high level.

The on/off control unit 18 stops the operation of the main switching element and the synchronous rectification element when the overvoltage detection signal _SOVP becomes high level.

The on/off control unit 18 performs current mode control of the main switching element and the synchronous rectification element based on the current information signal _{S_CINFO} obtained by adding the drain-source current of the main switching element to the sawtooth wave signal _{S_SAW} .

FIG. 9 is a diagram showing an example of a sawtooth wave signal, a current information signal, an error signal, and a main switching control signal of the backup power supply device according to the embodiment.

FIG. 9(a) is a diagram showing the main switching control signal _{S_SW1} when the drain-source current of the main switching element is not added to the sawtooth wave signal _{S_SAW} , that is, in the case of voltage mode control.

The _on /off control unit 18 sets the main switching control signal S _SW1 to a high level at timing t10 when the sawtooth wave signal S _SAW starts rising.

The _on /off control unit 18 changes the main switching control signal _SSW1 to a low level at timing _t11 when the sawtooth wave signal SSAW reaches the error signal _SERR .

FIG. 9(b) is a diagram showing the main switching control signal _{S_SW1} when the drain-source current of the main switching element is added to the sawtooth wave signal _{S_SAW} , that is, in the case of current mode control.

Signal 111 is indicative of the drain-to-source current of the main switching element. The current information signal _{S_CINFO} is a signal obtained by adding the signal 111 to the sawtooth wave signal _{S_SAW} .

The on/off control unit 18 sets the main switching control signal _{S_SW1} to a high level at timing _t20 when the current information signal _{S_CINFO} starts to rise.

The on/off control unit 18 changes the main switching control signal S- _SW1 to a low level at timing _t21 when the current information signal S _-CINFO reaches the error signal S- _ERR . When the main switching control signal _SSW1 becomes low level, the main switching element is turned off, so that the signal 111 becomes low level.

Referring to FIG. 1 again, when the mode signal S _MODE is at a high level (first mode), the drive selector 19 outputs the main switching control signal S _SW1 to the gate drive circuit _B1 , and outputs the synchronous rectification switching control signal S SW1 to the gate drive circuit B1. S _SW2 is _output to the gate drive circuit B2.

When the mode signal S _MODE is at low level ( _second mode), the drive selector 19 outputs the main switching control signal S _SW1 to the gate drive circuit B2, and outputs the synchronous rectification switching control signal S _SW2 to the gate drive circuit B2. Output to ₁ .

FIG. 10 is a diagram showing the circuit configuration of the drive selection unit of the backup power supply device according to the embodiment.

The drive selection unit 19 includes AND gate circuits (logical product circuits) 131 , 132 , 134 and 135 , OR gate circuits (logical sum circuits) 133 and 136 , and a NOT gate circuit 137 .

The NOT gate circuit 137 inverts the mode signal S _MODE and outputs it to one input terminal of the AND gate circuit 132 and one input terminal of the AND gate circuit 134 .

One input terminal of the AND gate circuit 131 receives the mode signal S _MODE , and the other input terminal receives the main switching control signal S _SW1 .

The other input terminal of the AND gate circuit 132 receives the synchronous rectification switching control signal _SSW2 .

The main switching control signal S _SW1 is input to the other input terminal of the AND gate circuit 134 .

One input terminal of the AND gate circuit 135 receives the mode signal S _MODE , and the other input terminal receives the synchronous rectification switching control signal S _SW2 .

The output signal of the AND gate circuit 131 is input to one input terminal of the OR gate circuit 133, and the output signal of the AND gate circuit 132 is input to the other input terminal.

The OR gate circuit 133 outputs the main switching control signal S _SW1 to the gate drive circuit _B1 when the mode signal S _MODE is at high level (first mode).

The OR gate circuit ₁₃₃ outputs the synchronous rectification switching control signal _{S_SW2} to the gate drive circuit B1 when the mode signal _{S_MODE} is at low level (second mode).

The output signal of the AND gate circuit 134 is input to one input terminal of the OR gate circuit 136, and the output signal of the AND gate circuit 135 is input to the other input terminal.

The OR gate circuit 136 outputs the synchronous rectification switching control signal S _SW2 to the gate drive circuit B2 when the mode signal S _MODE is at high level ( _first mode).

The OR gate circuit 136 outputs the main switching control signal S _SW1 to the gate drive circuit B2 when the mode signal S _MODE is at low level ( _second mode).

Referring to FIG. 1 again, when the mode signal S _MODE is at a high level (first mode), the gate drive circuit B ₁ outputs the switching control signal S 1 obtained by amplifying the main switching control signal S _{SW 1} to the switching element Q ₁ . output to the gate of

When the mode signal S _MODE is at low level ( _second mode), the gate drive circuit _B1 outputs the switching control signal S1, which is obtained by amplifying the synchronous rectification switching control signal S _SW2 , to the gate of the switching element _Q1 .

When the mode signal S _MODE is at _high level ( _first mode), the gate drive circuit B2 outputs the switching control signal S2, which is obtained by amplifying the synchronous rectification switching control signal S _SW2 , to the gate of the switching element _Q2 .

When the mode signal S _MODE is at low level _{( second} mode), the gate drive circuit B2 outputs the switching control signal S2, which is obtained by amplifying the main switching control signal _SSW1 , to the gate of the switching element _Q2 .

(effect)
[1] The backup power supply device described in Patent Document 1 performs switching control of only the second switching element during discharging, and does not control (do not operate) the first switching element. In other words, the backup power supply device described in Patent Document 1 performs an asynchronous rectification operation.

On the other hand, the backup power supply device 1 of the embodiment controls the switching of the switching element Q2 during discharging (during the _second mode), and controls the switching element _Q1 during a part of the period when the switching element _Q2 is off. turn on. In other words, the backup power supply device 1 of the embodiment operates the switching element _Q1 as a synchronous rectification element to perform a synchronous rectification operation.

As a result, the backup power supply device 1 of the embodiment can eliminate the need for an output rectifying element and reduce the number of parts, as compared with the backup power supply device described in Patent Document 1.

The backup power supply device described in Patent Document 1 performs switching control of only the first switching element during charging, does not control (does not operate) the second switching element, and causes the second switching element to function as a diode. In other words, the backup power supply device described in Patent Document 1 performs an asynchronous rectification operation.

On the other hand, the backup power supply device 1 of the embodiment controls the switching of the switching element _Q1 during charging (during the first mode), and controls the switching element _Q2 during a part of the period when the switching element _Q1 is off. turn on. That is, the backup power supply device 1 of the embodiment operates the switching element _Q2 as a synchronous rectification element to perform synchronous rectification.

As a result, the backup power supply device 1 of the embodiment can suppress losses and improve efficiency compared to the backup power supply device described in Patent Document 1.

[2] In the backup power supply device 1 of the embodiment, if the synchronous rectification element is left on during discontinuous current operation (light load), a reverse current flows and energy is regenerated to the input side. Less efficient. Further, in the backup power supply device 1 of the embodiment, when the charging voltage of the electric double layer capacitor 3 increases, the regenerative energy becomes larger than the charging energy, and charging to the target voltage becomes impossible. Therefore, in the backup power supply device 1 of the embodiment, the timing at which the coil L ₁ sweeps out the energy and the current between the drain and source of the synchronous rectification element becomes zero or is reversed, that is, the reversal detection signal S _REV is at a high level. The synchronous rectification element is controlled to be turned off at the timing. As a result, the backup power supply device 1 according to the embodiment can suppress backflow current and reduce efficiency. Further, the backup power supply device 1 of the embodiment can charge the charging voltage of the electric double layer capacitor 3 up to the target voltage.

[3] The backup power supply device 1 of the embodiment can charge while limiting the charging current in the first mode. However, in the second mode, the backup power supply device 1 of the embodiment must supply the electric power required by the electronic device while boosting it, so a large current may flow in the circuit.

Therefore, in the backup power supply device 1 of the embodiment, if the switching frequency is maintained during the _second mode, the size of the coil L1 must be increased. On the other hand, in the first mode, the backup power supply device 1 of the embodiment preferably does not set the switching frequency too high from the viewpoint of noise suppression.

Therefore, the switching frequency setting unit 13 sets the switching frequency in the second mode to a higher frequency than the switching frequency in the first mode. As a result, the backup power supply device ₁ of the embodiment can suppress the size of the coil L1 and noise.

[4] In the first mode, the backup power supply device 1 of the embodiment is based on the difference voltage between the voltage _VEDLC of the electric double layer capacitor 3, which is the output voltage of the step-up/down circuit 4, and the target voltage (specifically ₍ based on voltage V3). In the second mode, the backup power supply device 1 of the embodiment operates based on the difference voltage between the voltage _VN1 , which is the output voltage of the step-up/down circuit 4, and the target voltage ₍ specifically, based on the voltage V2). ) control.

However, if the input side of one error amplifier is switched between the above two voltages at the time of mode switching, a problem may occur. In other words, when the mode is switched, the input voltage of the error amplifier is switched to a completely different voltage level, so the output voltage of the error amplifier before mode switching and the output voltage of the error amplifier after mode switching are completely different voltages. becomes. Therefore, a delay in the response of the output voltage of the error amplifier and unstable operation may occur.

Therefore, the output voltage error detection section 17 (see FIG. 8) includes two error amplifiers 81 and 85, and switches the output side of the error amplifiers 81 and 85 at the time of mode switching. As a result, the error amplifiers 81 and 85 always keep outputting output voltages corresponding to their respective input voltages (even when they are not used for control), and response delays and unstable operations during mode switching can be suppressed. .

[5] The comparator can switch the input voltage to another voltage level, unlike the error amplifier. Therefore, the overvoltage detection unit 16 (see FIG. 7) includes one comparator 101, and switches the input voltage of the comparator 101 according to the mode. That is, in the first mode, a voltage V3 obtained by dividing the voltage _{V_EDLC} of the electric double layer capacitor ₃ by resistance is input to the comparator 101 . In the second mode, the input side of the comparator 101 switches the voltage obtained by dividing the voltage VN1, which is the output _voltage , by resistors.

As a result, the backup power supply device 1 of the embodiment can detect overvoltage in both the first mode and the second mode with one comparator 101, and can suppress the circuit.

[6] In general, current mode control is easier to perform phase compensation than voltage mode control, and can be set to increase response (increase frequency gain). Therefore, the on/off control section 18 employs current mode control in which the current information signal _{S-- CINFO} is taken into account. However, the current detection point differs between the first mode and the second mode.

Therefore, the current information detector 15 (see FIG. 6) switches the current information to be added to the sawtooth wave signal _{SSAW depending} on the mode. In other words, in the first mode, the current information detection section 15 detects the current information of the current flowing between the drain and source of the switching element _Q1 , which is the main switching element. In the second mode, the current information detection unit 15 detects current information about the current flowing between the drain and source of the switching element _Q2 , which is the main switching element.

As a result, the backup power supply device 1 of the embodiment can realize current mode control in both the first mode and the second mode.

[7] The control is completely different from the first mode and the second mode. Therefore, if mode switching is performed in the middle of a switching cycle, it will be an abnormal operation, even though it is one switching cycle.

Therefore, even if the mode change condition, that is, the magnitude relationship between the voltage _VIN and the input voltage threshold changes in the middle of the switching cycle, the mode switching timing adjustment unit 12 (see FIG. 2) is configured to start the next switching cycle, that is, After waiting until the periodic pulse signal S _OSC rises, the mode signal S _MODE is switched. Thereby, the backup power supply device 1 of the embodiment can suppress the abnormal operation.

<Appendix>
Although the control unit 10 is configured by a hardware circuit in the embodiment, the present disclosure is not limited to this. The control unit 10 may be composed of a processing device (CPU (Central Processing Unit), DSP (Digital Signal Processor), etc.) and a program.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and gist of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

1 Backup Power Supply Device 2 Battery 3 Electric Double Layer Capacitor 4 Buck-Boost Circuit 5 Terminal Section 10 Control Section 11 Battery Voltage Drop Monitoring Section 12 Mode Switching Timing Adjustment Section 13 Switching Frequency Setting Section 14 Switching Current Detection Section 15 Current Information Detection Section 16 Overvoltage Detector 17 Output voltage error detector 18 ON/OFF controller 19 Drive selector 20 _First level shifter 21 Second level shifter _Q1 , _Q2 switching element L1 coil

Claims (9)

an input terminal, an output terminal, a connection point electrically connected to the output terminal, and an input rectifying element having an anode electrically connected to the input terminal and a cathode electrically connected to the connection point. a terminal portion having a
an electric double layer capacitor having one end electrically connected to a reference potential;
a first switching element having one end electrically connected to the connection point;
a coil having one end electrically connected to the other end of the first switching element and the other end electrically connected to the other end of the electric double layer capacitor;
a second switching element having one end electrically connected to the other end of the first switching element and one end of the coil, and having the other end electrically connected to a reference potential;
When the input voltage input to the input terminal is equal to or higher than a predetermined first set voltage, the first switching element is switched on based on the current flowing through the first switching element and the charging voltage of the electric double layer capacitor. When the switching operation is performed to operate the first switching element and the coil as a step-down circuit to charge the electric double layer capacitor in a first mode, and the input voltage is less than the first set voltage. and switching the second switching element based on the current flowing through the second switching element and the output voltage output from the output terminal, thereby operating the second switching element and the coil as a booster circuit. a control unit that controls a second mode for discharging the electric double layer capacitor;
with
The control unit
In the first mode, the second switching element is switched as a synchronous rectification element of the step-down circuit, and in the second mode, the first switching element is switched as a synchronous rectification element of the step-up circuit.
A backup power supply, characterized by: The control unit
The second switching element is turned off at the timing when the current flowing through the second switching element becomes zero or reverses in the first mode, and the current flowing through the first switching element becomes zero in the second mode. turning off the first switching element at the timing of becoming or reversing
The backup power supply device according to claim 1, characterized by: The control unit
making the switching frequency of the second mode higher than the switching frequency of the first mode;
3. The backup power supply device according to claim 1 or 2, characterized in that: The control unit
a first error amplifier for detecting an error between a charging voltage of the electric double layer capacitor and a target charging voltage of the electric double layer capacitor;
a second error amplifier that detects an error between the output voltage and a target voltage of the output voltage;
has
In the first mode, the first error amplifier is used to control the charging voltage of the electric double layer capacitor, and in the second mode, the second error amplifier is used to control the output voltage.
The backup power supply device according to any one of claims 1 to 3, characterized in that: The control unit
In the first mode, when the charging voltage of the electric double layer capacitor reaches or exceeds a predetermined second set voltage, the switching operations of the first switching element and the second switching element are stopped, and the switching operation of the second switching element is stopped. In 2 modes, an overvoltage protection circuit that stops switching operations of the first switching element and the second switching element when the output voltage is equal to or higher than a predetermined third set voltage,
The backup power supply device according to any one of claims 1 to 4, characterized in that: The control unit
a sawtooth wave generation circuit for generating a sawtooth wave that determines switching frequencies of the first switching element and the second switching element;
Adding current information of a current flowing through the first switching element to the sawtooth wave in the first mode, and adding current information of a current flowing through the second switching element to the sawtooth wave in the second mode. to perform current mode control,
The backup power supply device according to any one of claims 1 to 5, characterized in that: The control unit
switching between the first mode and the second mode is performed at the start of a switching cycle;
The backup power supply device according to any one of claims 1 to 6, characterized in that: an input terminal, an output terminal, a node electrically connected to the output terminal, and an input rectifying element having an anode electrically connected to the input terminal and a cathode electrically connected to the node. a terminal portion, an electric double layer capacitor having one end electrically connected to a reference potential, a first switching element having one end electrically connected to the connection point, and one end connected to the other end of the first switching element. a coil electrically connected and having the other end electrically connected to the other end of the electric double layer capacitor; one end electrically connected to the other end of the first switching element and one end of the coil; A control method for a backup power supply device comprising: a second switching element having an end electrically connected to a reference potential;
When the input voltage input to the input terminal is equal to or higher than a predetermined first set voltage, the first switching element is switched on based on the current flowing through the first switching element and the charging voltage of the electric double layer capacitor. When the switching operation is performed to operate the first switching element and the coil as a step-down circuit to charge the electric double layer capacitor in a first mode, and the input voltage is less than the first set voltage. and switching the second switching element based on the current flowing through the second switching element and the output voltage output from the output terminal, thereby operating the second switching element and the coil as a booster circuit. to discharge the electric double layer capacitor, performing control in the second mode,
In the first mode, the second switching element is switched as a synchronous rectification element of the step-down circuit, and in the second mode, the first switching element is switched as a synchronous rectification element of the step-up circuit.
A control method characterized by: an input terminal, an output terminal, a node electrically connected to the output terminal, and an input rectifying element having an anode electrically connected to the input terminal and a cathode electrically connected to the node. a terminal portion, an electric double layer capacitor having one end electrically connected to a reference potential, a first switching element having one end electrically connected to the connection point, and one end connected to the other end of the first switching element. a coil electrically connected and having the other end electrically connected to the other end of the electric double layer capacitor; one end electrically connected to the other end of the first switching element and one end of the coil; A control program for a backup power supply device comprising: a second switching element having an end electrically connected to a reference potential;
When the input voltage input to the input terminal is equal to or higher than a predetermined first set voltage, the first switching element is switched on based on the current flowing through the first switching element and the charging voltage of the electric double layer capacitor. When the switching operation is performed to operate the first switching element and the coil as a step-down circuit to charge the electric double layer capacitor in a first mode, and the input voltage is less than the first set voltage. and switching the second switching element based on the current flowing through the second switching element and the output voltage output from the output terminal, thereby operating the second switching element and the coil as a booster circuit. to discharge the electric double layer capacitor, performing control in the second mode,
In the first mode, the second switching element is switched as a synchronous rectification element of the step-down circuit, and in the second mode, the first switching element is switched as a synchronous rectification element of the step-up circuit.
A control program that causes a processor to do things.

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