JP2021111991A - Power transfer circuit and power transfer method - Google Patents

Abstract

To provide a power transfer circuit capable of stably utilizing an apparatus even in the case where different kinds of power sources are used in a combined manner.SOLUTION: The present invention relates to a power transfer circuit configured to supply power to a load circuit using a plurality of power sources. The power transfer circuit comprises: a first power supply line and a second power supply line for supplying power to the load circuit; a first power storage section including a capacitor group constituted of a plurality of first capacitors which are connected in series with each other between the first power supply line and the second power supply line and each of which forms a closed circuit via each of the plurality of power sources and a switch; and a second power storage section including a second capacitor which is connected in parallel with the capacitor group between the first power supply line and the second power supply line and forms a closed circuit via the capacitor group and the switches.SELECTED DRAWING: Figure 1

Description

The present invention relates to a power transfer circuit and a power transfer method.

Electronic devices that operate using a plurality of batteries connected in series as a power source are widely used. In such an electronic device, the battery needs to be replaced by the user as the battery is consumed. When this battery replacement is performed, the battery may be erroneously loaded into the battery case. For example, a user may mistakenly load a mixture of used batteries and unused batteries into a battery case. In addition, the user may mistakenly mount the positive and negative electrodes of some batteries in the opposite directions, or mix different types of batteries (for example, alkaline batteries and manganese batteries) and load them into the battery case. be. In such a case, excessive charging / discharging may occur in a specific battery, which may cause deformation of the battery, liquid leakage, or the like.

In order to prevent such erroneous loading of batteries, by monitoring the power supply voltage value, it is determined whether or not all the batteries have been replaced with new ones, and all the batteries are replaced even though the batteries have been replaced. A device has been proposed for notifying that an abnormal battery replacement has been performed when it is determined that the battery is not new (for example, Patent Document 1).
Further, in order to prevent a short-circuit between the positive terminal and the negative terminal of the battery accommodating chamber when the battery pack in which the secondary batteries are connected in series is reversely loaded, a short-circuiting means is provided inside the lid that closes the battery accommodating chamber to provide the battery. A battery pack and a battery storage chamber structure have been proposed in which a secondary battery is connected in series between the positive terminal and the negative terminal of the battery storage chamber only when the pack is correctly loaded. (For example, Patent Document 2).

JP-A-2017-44406 Japanese Unexamined Patent Publication No. 2002-141033

In the device of Patent Document 1, the user re-installs the battery upon receiving the notification that the abnormal battery has been replaced, so that the battery is correctly installed. However, since there are not a few users who leave the notification from the device as it is, there is a problem that it cannot be said that the state in which the battery is properly installed is surely realized.

Further, when the device is configured so that the device does not operate when the battery is erroneously loaded as in Patent Document 2, the user does not operate the device even though the battery is replaced with a new one. Therefore, the device is not erroneously loaded. There was a problem of suspecting the failure of the battery.

In addition, there are cases where different types of power sources must be used in combination instead of misloading the batteries. In such cases, the device such as the above-mentioned conventional technology cannot supply power to the load itself. There was a problem that it might end up.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a power transfer circuit capable of stably using a device even when different types of power sources are used in combination.

The power transfer circuit according to the present invention is a power transfer circuit that supplies power to a load circuit using a plurality of power sources, and is a first power supply line and a second power supply line that supply power to the load circuit. And a plurality of first power lines connected in series with each other between the first power supply line and the second power supply line, and each forming a closed circuit with each of the plurality of power supplies via a switch. A first power storage unit having a group of capacitors composed of the above capacitors, and the first power supply line and the second power supply line are connected in parallel with the capacitor group, and the capacitor group and a switch are connected. It is characterized by having a second power storage unit including a second capacitor that forms a closed circuit through the circuit.

Further, in the power transfer method according to the present invention, the first power supply line and the second power supply line connected to the load circuit are connected in series with each other, and each of the plurality of power supplies and a switch are used. A first power storage unit having a capacitor group composed of a plurality of first capacitors forming a closed circuit, and parallel to the capacitor group between the first power supply line and the second power supply line. A power transfer circuit including a second power storage unit including the second capacitor which is connected to the capacitor group and forms a closed circuit via a switch transfers power from the plurality of power sources to the load circuit. It is a power transfer method for transferring, and by turning on the switch of the first power storage unit and turning off the switch of the second power storage unit, charges from the plurality of power sources are accumulated in the capacitor group. At the same time, the first step of supplying power to the load circuit based on the charge stored in the second capacitor and the switch of the first power storage unit are turned off, and the second power storage unit is turned off. By turning on the switch, the charge stored in the capacitor group is moved to the second capacitor, and the load circuit is supplied with power based on the charge stored in the capacitor group. It is characterized by including the steps of.

According to the present invention, the device can be used stably even when different types of power sources are used in combination.

It is a circuit diagram which shows the structure of the power transfer circuit which concerns on Example 1 of this invention. It is a table showing the relationship between the switching of each switch and the mode transition. It is a circuit diagram which shows the state of the power transfer circuit in mode I. It is a circuit diagram which shows the state of the power transfer circuit in mode II and mode IV. It is a circuit diagram which shows the state of the power transfer circuit in mode III. It is a figure which shows typically the voltage change in each mode. It is a circuit diagram which shows the structure of the power transfer circuit which concerns on Example 2 of this invention. It is a circuit diagram which shows the structure of the power transfer circuit which concerns on the modification of Example 2. FIG.

Hereinafter, examples of the present invention will be described with reference to the drawings. In the description and the accompanying drawings in each of the following examples, substantially the same or equivalent parts are designated by the same reference numerals.

FIG. 1 is a circuit diagram showing the configuration of the power transfer circuit 100 of this embodiment. The power transfer circuit 100 is connected to a battery case (not shown) accommodating three batteries BT1, BT2, and BT3, and the voltage generated by each of the batteries BT1 to BT3 is applied to the first power supply line LA and the first power supply line LA. This is a circuit that supplies the load circuit 14 via the power supply line LB of 2.

The power transfer circuit 100 includes an energy storage circuit 11 composed of switches SW1, SW2 and SW3, and capacitors C1, C2 and C3. The switches SW1, SW2 and SW3 are composed of transistors such as MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors). Capacitors C1, C2 and C3 are composed of non-polar capacitors.

One end of the switch SW1 is connected to the positive electrode side terminal of the battery BT1. The other end of the switch SW1 is connected to one end of the capacitor C1. The other end of the capacitor C1 is connected to the negative electrode side terminal of the battery BT1. When the switch SW1 is turned on, a closed circuit including the battery BT1 and the capacitor C1 is formed.

One end of the switch SW2 is connected to the positive electrode side terminal of the battery BT2. The other end of the switch SW2 is connected to one end of the capacitor C2. The other end of the capacitor C2 is connected to the negative electrode side terminal of the battery BT2. When the switch SW2 is turned on, a closed circuit including the battery BT2 and the capacitor C2 is formed. The connection end between one end of the capacitor C2 and the other end of the switch SW2 is connected to the connection end between the other end of the capacitor C1 and the negative electrode side terminal of the battery BT1.

One end of the switch SW3 is connected to the positive electrode side terminal of the battery BT3. The other end of the switch SW3 is connected to one end of the capacitor C3. The other end of the capacitor C3 is connected to the negative electrode side terminal of the battery BT3 and is grounded. When the switch SW3 is turned on, a closed circuit including the battery BT3 and the capacitor C3 is formed. The connection end between one end of the capacitor C3 and the other end of the switch SW3 is connected to the connection end between the other end of the capacitor C2 and the negative electrode side terminal of the battery BT2.

The energy storage circuit 11 has a function of storing the energy output from the batteries BT1, BT2, and BT3. That is, when the switch SW1 is turned on, an electric charge is accumulated in the capacitor C1 based on the current output from the battery BT1. Similarly, when the switch SW2 is turned on, an electric charge is accumulated in the capacitor C2 based on the current output from the battery BT2. When the switch SW3 is turned on, an electric charge is accumulated in the capacitor C3 based on the current output from the battery BT3.

That is, each of the capacitors C1, C2, and C3 is a first capacitor that temporarily stores the electric power from the batteries BT1, BT2, and BT3. The energy storage circuit 11 is a first power storage unit that stores the power output from the batteries BT1, BT2, and BT3.

Further, the power transfer circuit 100 has an energy supply circuit 12 composed of a switch SW4 and a capacitor Cin. The switch S4 is composed of transistors such as MOSFETs.

The switch SW4 is a changeover switch for switching between connection and non-connection between the capacitors C1, C2 and C3 and the capacitor C4. One end of the switch SW4 is connected to one end of the capacitor C1. The other end of the switch SW4 is connected to one end of the capacitor Cin.

The capacitor Cin is a second capacitor that stores charges transferred from the first capacitors C1, C2 and C3 (that is, a group of capacitors). The other end of the capacitor Cin is connected to the other end of the capacitor C3 and is grounded. When the switch SW4 is turned on, a closed circuit including the capacitors C1, C2 and C3 and the capacitor Cin is formed.

The energy supply circuit 12 has a function of supplying the energy stored in the energy storage circuit 11 to the load circuit 14. That is, when the switch SW4 is turned on, the electric charge accumulated in the capacitors C1, C2 and C3 moves to the capacitor Cin and is accumulated. Then, when the switch SW4 is turned off, the electric charge accumulated in the capacitor Cin is supplied to the load circuit 14. The energy supply circuit 12 is a second power storage unit that further stores the charges stored in the capacitors C1, C2, and C3 based on the power output from the batteries BT1, BT2, and BT3.

Further, the power transfer circuit 100 has a reverse bias prevention circuit 13 composed of a diode D1.

The anode of the diode D1 is connected to the other end of the capacitor Cin and the other end of the capacitor C3 and is grounded. The cathode of the diode D1 is connected to the other end of the capacitor Cin and the other end of the capacitor C3 and is grounded.

The reverse bias prevention circuit 13 has a function of suppressing the reverse bias from being applied to the load circuit 14. For example, when two or more batteries BT1, BT2, and BT3 are loaded in the battery case in the opposite directions, the total potential of the capacitors C1 to C3 and the potential of the capacitors Cin become negative potentials with reference to the ground potential VSS. At that time, the voltage applied to the load circuit 14 (that is, reverse bias) is suppressed to a voltage corresponding to the voltage drop of the diode D1 due to the current flowing through the diode D1. As a result, the load circuit 14 is protected.

Further, the power transfer circuit 100 has an internal power supply circuit 21 and a switching control circuit 22.

The internal power supply circuit 21 generates an internal power supply voltage based on the potential difference between both ends of the battery BT1 and supplies it to the switching control circuit 22. The internal power supply circuit 21 includes a polarity determination circuit (not shown) that determines the polarity of the potentials at both ends of the battery BT1 with reference to the ground potential VSS, and a polarity inversion circuit (not shown) that inverts the polarity when the potential is negative. (Not shown) is included. By operating the polarity determination circuit and the polarity inversion circuit, for example, even when the battery BT1 is loaded in the reverse direction in the battery case, the positive internal power supply voltage can be supplied to the switching control circuit 22.

The switching control circuit 22 operates based on the internal power supply voltage supplied from the internal power supply circuit 21, and controls the on / off switching of the switches SW1, SW2, SW3 and SW4.

Next, the operation of the power transfer circuit 100 of this embodiment will be described with reference to FIGS. 2 to 6.

FIG. 2 is a diagram showing how the switches SW1 to SW4 are switched as a table.

[Mode I]
The changeover control circuit 22 controls the changeover of each switch so that the switches SW1, SW2 and SW3 are turned on and the switch SW4 is turned off. As a result, the power transfer circuit 100 is in the "mode I" state.

FIG. 3 is a circuit diagram showing a state of the power transfer circuit 100 in mode I. Note that the internal power supply circuit 21 and the switching control circuit 22 are not shown here.

When SW1 is turned on, a closed circuit composed of the battery BT1 and the capacitor C1 is formed, and the electric charge is transferred to and accumulated in the capacitor C1 based on the current output from the battery BT1. Assuming that the charge stored in the capacitor C1 is ΔQc11, the capacitance of the capacitor C1 is Cc1, and the voltage change of the voltage Vc1 between the terminals of the capacitor C1 is ΔVc11, the relationship between ΔQc11, Cc1 and ΔVc11 is calculated by the following equation (1). expressed.

Further, assuming that the current flowing from the battery BT1 to the capacitor C1 is Ib1 and the length of the mode I period (hereinafter referred to as the period T1) is ton1, ΔQc11 is expressed by the following mathematical formula (2).

Then, from the mathematical formula (1) and the mathematical formula (2), ΔVc11 is represented by the following mathematical formula (3).

Further, when SW2 is turned on, a closed circuit composed of batteries BT2 and C2 is formed, and electric charges are transferred to and accumulated in the capacitor C2 based on the current output from the battery BT2. Assuming that the charge accumulated in the capacitor C2 is ΔQc21, the capacitance of the capacitor C2 is Cc2, and the voltage change of the voltage Vc2 between the terminals of the capacitor C2 is ΔVc21, the relationship between ΔQc21, Cc2 and ΔVc21 is calculated by the following equation (4). expressed.

Further, assuming that the current flowing from the battery BT2 to the capacitor C2 is Ib2, ΔQc21 is expressed by the following mathematical formula (5).

Then, from the mathematical formula (4) and the mathematical formula (5), ΔVc21 is represented by the following mathematical formula (6).

Further, when the SW3 is turned on, a closed circuit composed of the batteries BT3 and C3 is formed, and the electric charge is transferred to and accumulated in the capacitor C3 based on the current output from the battery BT3. Assuming that the charge accumulated in the capacitor C3 is ΔQc31, the capacitance of the capacitor C3 is Cc3, and the voltage change of Vc3 of the voltage between terminals of the capacitor C3 is ΔVc31, the relationship between ΔQc31, Cc3 and ΔVc31 is calculated by the following equation (7). It is represented by.

Further, assuming that the current flowing from the battery BT3 to the capacitor C3 is Ib3, ΔQc31 is expressed by the following mathematical formula (8).

Then, from the mathematical formula (7) and the mathematical formula (8), ΔVc31 is represented by the following mathematical formula (9).

Here, in ton1, the terminal voltage Vc1 of the capacitor C1 is up to the voltage Vbt1 of the battery BT1, the terminal voltage Vc2 of the capacitor C2 is up to the voltage Vbt2 of the battery BT2, and the terminal voltage V3 of the capacitor C3 is the voltage of the battery BT3. It is desirable to set the charging time up to Vbt3.

Further, the period T1 is a time during which the charges from the batteries BT1, BT2 and BT3 are accumulated in the capacitors C1, C2 and C3, and is also a period during which energy is supplied from the capacitor Cin to the load circuit 14. Assuming that the charge supplied (that is, released) by the capacitor Cin to the load circuit 14 is ΔQcin1, the capacitance of the capacitor Cin is Ccin, the voltage change of the capacitor Cin due to the discharge of the charge is ΔVcin1, and the current consumption of the load circuit 14 is Iin. These are represented by the following equations (10) and (11).

Then, from the mathematical formula (10) and the mathematical formula (11), ΔVcin1 is represented by the following mathematical formula (12).

As described above, the mode I is a charge storage mode in which power is supplied from the capacitor Cin to the load circuit 14 and the charges from the batteries BT1, BT2 and BT3 are stored in the capacitors C1, C2 and C3.

[Mode II]
Next, the switching control circuit 22 switches the switches SW1, SW2, and SW3 off. As a result, the switches SW1, SW2, SW3 and SW4 are all turned off, and the power transfer circuit 100 is in the "mode II" state.

FIG. 4 is a circuit diagram showing a state of the power transfer circuit 100 in mode II. Note that the internal power supply circuit 21 and the switching control circuit 22 are not shown here.

When the switches SW1, SW2 and SW3 are turned off, the connection between the battery BT1 and the capacitor C1, the connection between the battery BT2 and the capacitor C2, and the connection between the battery BT3 and the capacitor C3 are disconnected. That is, the period of mode II (hereinafter referred to as period T2) is a so-called dead time period provided so that an abnormal voltage such as an overvoltage or a reverse voltage is not applied to the batteries BT1, BT2 and BT3.

The period T2 is also a period for supplying energy from the capacitor Cin to the load circuit 14. Assuming that the charge supplied (that is, released) by the capacitor Cin to the load circuit 14 is ΔQcin2, the voltage change of the capacitor Cin due to the discharge of the charge is ΔVcin2, and the length of the period T2 is ton2, these are the following equations (13) and equations. It is represented by (14).

Then, from the mathematical formula (10) and the mathematical formula (11), ΔVcin2 is represented by the following mathematical formula (12).

[Mode III]
Next, the switching control circuit 22 switches the switch S4 on. As a result, the switches SW1, SW2 and SW3 are turned off, the switch SW4 is turned on, and the power transfer circuit 100 is in the "mode III" state.

FIG. 5 is a circuit diagram showing a state of the power transfer circuit 100 in mode III. Note that the internal power supply circuit 21 and the switching control circuit 22 are not shown here.

When SW4 is turned on, a closed circuit composed of capacitors C1, C2, C3 and Cin is formed. As a result, the charges of the capacitors C1, C2 and C3 are transferred to the capacitors Cin and accumulated. The inter-terminal voltage Vcin of the capacitor Cin is charged up to the total value Vcc of the inter-terminal voltages Vc1, Vc2 and Vc3 of the capacitors C1, C2 and C3. The period of mode III (hereinafter referred to as period T3) is also a period of supplying energy from the capacitors C1, C2 and C3 to the load circuit 14.

Assuming that the charge supplied (that is, released) by the capacitor C1 to the load circuit 14 is ΔQc13, the change in the voltage Vc1 between terminals of the capacitor C1 is ΔVc13, the current consumption of the capacitor Cin is Icin, and the length of the period T3 is ton3. ΔQc13 is represented by the following mathematical formulas (16) and (17).

Then, from the mathematical formula (16) and the mathematical formula (17), ΔVc13 is represented by the following mathematical formula (18).

Further, assuming that the charge supplied (that is, released) by the capacitor C2 to the load circuit 14 is ΔQc23 and the change in the voltage Vc2 between terminals of the capacitor C2 due to this is ΔVc23, ΔQc23 is calculated by the following equations (19) and (20). expressed.

Then, from the mathematical formula (19) and the mathematical formula (20), ΔVc23 is represented by the following mathematical formula (21).

Further, assuming that the charge supplied (that is, released) by the capacitor C3 to the load circuit 14 is ΔQc33 and the change in the voltage Vc3 between terminals of the capacitor C3 due to this is ΔVc33, ΔQc33 is calculated by the following equations (22) and (23). expressed.

Then, from the mathematical formula (22) and the mathematical formula (23), ΔVc33 is represented by the following mathematical formula (24).

On the other hand, assuming that the charge supplied from the capacitors C1, C2 and C3 to the capacitor Cin is ΔQcin3 and the change in the voltage Vcin between the terminals of the capacitor Cin is ΔVcin3, ΔQcin3 is expressed by the following equations (25) and (26). Will be done.

Then, from the mathematical formula (25) and the mathematical formula (26), ΔVcin3 is represented by the following mathematical formula (27).

Here, it is desirable that ton3 is set to a time during which the inter-terminal voltage Vcin of the capacitor Cin is charged to the total value Vcc of the inter-terminal voltages Vc1, Vc2 and Vc3 of the capacitors C1, C2 and C3.

As described above, the mode III is a charge transfer mode in which power is supplied from the capacitors C1, C2 and C3 to the load circuit 14 and the charges stored in the capacitors C1, C2 and C3 are transferred to the capacitors Cin.

[Mode IV]
Next, the changeover control circuit 22 switches the switch S4 off. As a result, the switches SW1, SW2, SW3 and SW4 are all turned off, and the power transfer circuit 100 is in the "mode IV" state.

Similar to the circuit state in mode II shown in FIG. 2, since all the switches are off, the connection between the battery BT1 and the capacitor C1, the connection between the battery BT2 and the capacitor C2, and the connection between the battery BT3 and the capacitor C3, and The connections between the capacitors C1 to C3 and the capacitors Cin are disconnected from each other. Similar to the period T2, the period of this mode IV (hereinafter referred to as the period T4) is also a so-called dead time period provided so that an abnormal voltage such as an overvoltage or a reverse voltage is not applied to the batteries BT1, BT2 and BT3. Is.

The period T4 is also a period for supplying energy from the capacitor Cin to the load circuit 14. Assuming that the charge supplied (that is, released) by the capacitor Cin to the load circuit 14 is ΔQcin4, the voltage change of the capacitor Cin due to the discharge of the charge is ΔVcin4, and the length of the period T4 is ton4, these are the following equations (28) and equations. It is represented by (29).

Then, from the mathematical formula (28) and the mathematical formula (29), ΔVcin4 is represented by the following mathematical formula (30).

The switch is switched as described above, and the circuit state of the power transfer circuit 100 changes from mode I to IV. After mode IV, the mode returns to mode I again, and the same switch switching and circuit state change are repeated.

FIG. 6 is a diagram schematically showing a voltage change in each mode. Here, the voltage change of the voltage Vcin between the terminals of the capacitor Cin is shown by a solid line. Further, the voltage between terminals of one of the capacitors C1, C2 and C3 is defined as Vc, and the voltage change is shown by a chain double-dashed line.

Since it is necessary to charge the capacitors C1, C2 and C3 to a sufficient voltage level in the mode I, the length of the period T1 (ton1) is set longer here. Further, in mode III, since it is necessary to charge the capacitor Cin to a sufficient voltage level, the length of the period T3 (ton3) is set longer here.

In the period T1 (mode I), the electric charge accumulated in the capacitor Cin is supplied to the load circuit 14, so that the voltage Vin between the terminals of the capacitor Cin decreases. On the other hand, electric charges are accumulated in the capacitors C1, C2 and C3 by the currents from the batteries BT1, BT2 and BT3, respectively, and the voltage Vc between terminals rises. The voltage Vc between the terminals of the capacitors C1, C2 and C3 rises to the voltage values Vbt of the batteries BT1, BT2 and BT3 and becomes constant.

In the period T2 (mode II), the charge accumulated in the capacitor Cin is still supplied to the load circuit 14, so that the voltage Vin between the terminals of the capacitor Cin drops. On the other hand, since the capacitors C1, C2 and C3 are separated from the batteries BT1, BT2 and BT3, the voltage value (that is, Vbt) of the conventional inter-terminal voltage Vc is maintained.

In period T3 (mode III), the capacitor Cin is disconnected from the load circuit 14 and connected to the capacitors C1, C2 and C3. Therefore, the electric charge from the capacitors C1, C2, and C3 accumulates the electric charge in the capacitor Cin, and the voltage Vcin between the terminals of the capacitor Cin rises. The voltage Vcin between the terminals of the capacitor Cin rises to the maximum value Vcinmax and becomes constant. On the other hand, the capacitors C1, C2 and C3 supply electric charges to the capacitors Cin and also supply electric charges to the load circuit 14. Therefore, the voltage Vc between the terminals of the capacitors C1, C2, and C3 decreases and becomes constant at a certain voltage level (shown as Vst in FIG. 6).

In the period T4 (mode IV), the electric charge accumulated in the capacitor Cin is supplied to the load circuit 14, so that the voltage Vin between the terminals of the capacitor Cin drops. On the other hand, the capacitors C1, C2 and C3 are in a state of being disconnected from the batteries BT1, BT2 and BT3 and the load circuit 14, and the voltage value (that is, Vst) of the conventional inter-terminal voltage Vc is maintained.

Mode I, mode II, and mode IV are periods during which the capacitor Cin supplies energy to the load circuit 14. On the other hand, mode III is a period in which energy is supplied from the capacitors C1, C2 and C3 to the capacitor Cin. Therefore, the sum of the voltage changes between the terminals Vcin in modes I, II, and IV needs to match the voltage changes in the voltage Vcin between the terminals in mode III. That is, the voltage change of the voltage Vcin between the terminals of the capacitor Cin is expressed by the following mathematical formula (31).

Substituting the mathematical formula (12), the mathematical formula (15), the mathematical formula (27) and the mathematical formula (30) into the mathematical formula (31), the following mathematical formula (32) is obtained.

By repeating modes I to IV so as to satisfy this mathematical formula (32), energy can be continuously supplied from the batteries BT1, BT2, and BT3 to the load circuit 14.

Here, assuming that the repetition period is T, T is expressed by the following mathematical formula (33).

From the formula (12), the formula (15), the formula (30), and the formula (33), the total voltage change ΔVcin of the voltage Vcin between the terminals of the capacitor Cin is expressed by the following formula (34).

On the other hand, since the capacitors C1, C2 and C3 connected in series and the capacitor Cin are connected in parallel, the voltage change ΔVcin of the voltage Vcin between the terminals of the capacitor Cin is the voltage of the voltage between the terminals of the capacitors C1, C2 and C3. It is equal to the sum of the changes ΔVc1, ΔVc2 and ΔVc3. That is, the voltage change of the voltage between the terminals of each capacitor has the relationship expressed by the following mathematical formula (35).

As can be seen from the above equation (34), by shortening the repetition period T and increasing the switching frequency fsw (fsw = 1 / T) of the switches SW1 to SW4, the voltage change ΔVcin of the voltage between the terminals of the capacitor Cin Can be made smaller. As shown in the equation (35), ΔVcin is the sum of the voltage changes ΔVc1, ΔVc2 and ΔVc3 of the voltage between the terminals of the capacitors C1, C2 and C3. Therefore, when the switching frequency fsw is increased, ΔVc1 to ΔVc3 can also be decreased. can.

Then, by increasing fsw to minimize ΔVc1 to ΔVc3, the inter-terminal voltages Vc1 to Vc3 of the capacitors C1 to C3 are almost unchanged, and it is considered to be the same as Vbt1 to Vbt3 which are the voltages of the batteries BT1 to BT3. The effect of being able to do so is obtained. As a result, even when the mode IV is changed to the mode I, it can be expected that an abnormal voltage such as an overvoltage or a reverse voltage is not applied to the capacitors C1 to C3.

As described above, in the power transfer circuit 100 of this embodiment, the energy of the batteries BT1, BT2 and BT3, that is, the output currents from the batteries BT1, BT2 and BT3 are temporarily stored in the capacitors C1, C2 and C3 as electric charges. .. Then, the accumulated charge is supplied to the load circuit 14 via the capacitor Cin (modes I, II, IV), or is directly supplied to the load circuit 14 from the capacitors C1, C2, and C3 (mode III). This prevents overvoltage, reverse voltage, etc. from being applied to the battery itself even when the old and new batteries are mixed and loaded in the battery case or loaded in the opposite direction. be able to. Further, since the energy of the batteries BT1, BT2 and BT3 is transferred to different capacitors C1, C2 and C3, the voltage difference between the batteries does not matter, and different types of batteries such as alkaline batteries and lithium batteries are mixed. Even when used in combination, stable power transfer can be performed.

Next, Example 2 of the present invention will be described. FIG. 7 is a circuit diagram showing the configuration of the power transfer circuit 200 of this embodiment.

In the power transfer circuit 200 of this embodiment, the switching control circuit 22 monitors the voltage applied from the energy supply circuit 12 to the load circuit 14, and switches the switch SW4 based on the voltage value obtained by the monitoring. Therefore, it is different from the power transfer circuit 100 of the first embodiment.

The switching control circuit 22 is connected to the first power supply line LA and the second power supply line LB of the load circuit 14 via a pair of signal lines. The switching control circuit 22 obtains information on the potential of the first power supply line LA and the potential of the second power supply line LB via the pair of signal lines. Then, the switching control circuit 22 switches the switch SW4 on and off based on the potential difference between the first power supply line LA and the second power supply line LB.

Specifically, the switching control circuit 22 controls the length of the on time of the switch SW4 in the mode III, that is, the length ton3 of the period T3 so that the potential difference becomes a desired voltage value. For example, when the allowable input voltage of the load circuit 14 is lower than the maximum value of the voltage between terminals of the capacitor Cin (see Vcinmax in FIG. 6), the switch is switched when the voltage Vcin between terminals of the capacitor Cin does not reach the maximum value. Switch SW4 off.

According to the power transfer circuit 200 of this embodiment, the voltage supplied to the load circuit 14 is monitored, and the length of the period during which the switch SW4 is turned on based on the voltage value (the length of the period T3 of the mode III). By controlling ton3), it is possible to prevent an excessive voltage from being applied to the load circuit 14.

FIG. 8 is a circuit diagram showing the configuration of the power transfer circuit 300 of the modified example of the second embodiment. The power transfer circuit 300 of the first embodiment has an energy supply circuit 32 having a configuration different from that of the energy supply circuit 12 of FIG. 1 and a control circuit 35 for controlling the energy supply circuit 32. Different from.

The energy supply circuit 32 includes a switch SW4, a capacitor Cin, an inductor L1, a switch SW5, a diode D2, and a capacitor Cx.

The inductor L1 is inserted in the first power supply line LA. One end of the inductor L1 is connected to one end of the capacitor Cin and the other end of the switch SW4.

The switch SW5 is connected in parallel to the capacitor Cin. One end of the switch SW5 is connected to the first power supply line LA, and is connected to the other end of the inductor L1 via the first power supply line LA. The other end of the switch SW5 is connected to the second power supply line LB.

The diode D2 is connected in series with the inductor L1 and is inserted into the first power supply line LA. The anode of the diode D2 is connected to the other end of the inductor L1 and one end of the switch SW5.

The capacitor Cx is connected in parallel to the capacitor Cin and the switch SW5. One end of the capacitor Cx is connected to the cathode of the diode D2. The other end of the capacitor Cx is connected to the second power supply line LB.

A booster circuit is formed by the inductor L1, the switch SW5, the diode D2, and the capacitor Cx. Specifically, when the switch SW5 is turned on, the other end of the inductor L1 is connected to the ground line (VSS), and energy is stored in the inductor L1. Then, when the switch SW5 is turned off, the energy of the inductor L1 is added to the inter-terminal voltage Vcin of the capacitor Cin, and the voltage obtained by boosting the inter-terminal voltage Vcin of the capacitor Cin is supplied to the load circuit 14 via the diode D2.

The control circuit 35 has a pair of input lines connected to both ends of the capacitor Cin. The inter-terminal voltage Vcin of the capacitor Cin is supplied to the control circuit 35 as a power supply voltage via the pair of input lines.

Further, the control circuit 35 is connected to the first power supply line LA and the second power supply line LB of the load circuit 14 via a pair of signal lines. The switching control circuit 22 obtains information on the potential of the first power supply line LA and the potential of the second power supply line LB via the pair of signal lines. Then, the control circuit 35 switches the switch SW5 on and off based on the potential difference between the first power supply line LA and the second power supply line LB.

Specifically, the control circuit 35 monitors the potential of the first power supply line LA and the voltage supplied to the load circuit 14 via the second power supply line LB, and the voltage value of the voltage is the load circuit. When the operating voltage of 14 is not reached, the switching operation of the switch SW5 is performed. As a result, the voltage obtained by boosting the inter-terminal voltage Vcin of the capacitor Cin is supplied to the load circuit 14.

According to this configuration, when the total voltage value of the batteries BT1 to BT3 is low due to a mixture of old and new batteries or reverse loading of the batteries in the battery case, the voltage supplied to the load circuit 14 is applied to the operation of the load circuit 14. It can be boosted to voltage. This makes it possible to effectively utilize the energy of the batteries BT1 to BT3.

The embodiments of the present invention are not limited to those described in the above examples. For example, in the above embodiment, the switches SW1 to SW3 are connected between one end of the batteries BT1 to BT3 and the capacitors C1 to C3. However, the positions of the switches SW1 to SW3 are not limited to this, and may be connected between the other ends of the batteries BT1 to BT3 and the other ends of the capacitors C1 to C3, for example. That is, the switches SW1 to SW3 may be located in the charging path where the batteries BT1 to BT3 charge the capacitors C1 to C3.

Further, in the above embodiment, the switch SW4 is connected between one end of the capacitor C1 and one end of the capacitor Cin. However, the position of the switch SW4 is not limited to this, and may be in the current path of the capacitors C1 to C3 and the capacitor Cin (however, other than the path where the batteries BT1 to BT3 charge the capacitors C1 to C3).

Further, in the above embodiment, the other end of the capacitor C3 and the capacitor Cin is grounded and the ground potential VSS is used as the reference point of the circuit, but for example, it may be in a floating state.

Further, in the above embodiment, the energy storage circuit 11, the energy supply circuit 12, and the reverse bias prevention circuit 13 have been described as separate circuit blocks, but the division of the circuit blocks is not limited to this, and the same functions are realized as a whole. It suffices if it is done. For example, the reverse bias prevention circuit 13 may be incorporated in the energy supply circuit 12. When the reverse bias prevention circuit 13 is used as a bridge diode, it is possible to prevent the reverse bias of the load circuit 14 and supply electric power to the load circuit 14. Further, when the reverse load of the battery does not obviously occur in terms of application, it is not necessary to provide the reverse bias prevention circuit 13 or a function corresponding thereto.

Further, the capacitor Cin may be composed of a non-polar capacitor or a polar capacitor. When a non-polar capacitor is used as the capacitor Cin, the total potential of the capacitors C1, C2 and C3 is the ground potential VSS when two or more of the batteries BT1, BT2 and BT3 are loaded in the battery case in the opposite direction. It is possible to deal with cases where the value becomes negative based on. On the other hand, when a polar capacitor is used, it has a larger capacity and a smaller scale than a non-polar capacitor, so that it is possible to realize a power transfer circuit having a smaller circuit scale.

Further, in the above embodiment, the case where three batteries BT1, BT2 and BT3 are used has been described, but the number of batteries is not limited to this. It can be applied when at least two or more batteries are used.

Further, when the switching frequency fsw for switching the switches SW1 to SW3 on and off cannot be increased, a capacitor as an energy auxiliary storage element may be added in parallel with the batteries BT1 to BT3. For example, by connecting an energy auxiliary storage element at a position facing the capacitors C1 to C3 across the batteries BT1 to BT3, it is possible to absorb the difference in voltage between the batteries BT1 to BT3 and the capacitors C1 to C3. You can expect it. Further, by adding this energy auxiliary storage element, the charging speed of the capacitors C1 to C3 in the mode I can be increased, which is effective even when the switching frequency fsw is increased.

Further, when the power transfer circuit is started (that is, immediately after the power is turned on), the mode I period (period T1) is extended, the capacitors C1 to C3 are charged to the potentials of the batteries BT1 to BT3, and then the switching operation is started. Then it is good.

Further, in the second embodiment, an example in which the switching control circuit 22 switches the switch SW4 according to the voltage applied from the energy supply circuit 12 to the load circuit 14 has been described. However, the switching control circuit 22 may be configured to switch the switches SW1 to SW3 according to the voltage applied to the load circuit 14.

Further, in the second embodiment, the case where the switching control circuit 22 is connected between the reverse bias prevention circuit 13 and the load circuit 14 via a pair of signal lines is shown in FIG. 7. It may be connected to the supply line LA and the second power supply line LB, and may be connected between, for example, the energy supply circuit 12 and the reverse bias prevention circuit 13.

Further, in the above embodiment, the case where a battery is used as an energy source has been described as an example, but the present invention is not limited to this, and can be applied to various energy sources having different voltage values such as energy harvesting and renewable energy. be. According to this configuration, it is possible to add up the power from different types of power sources and supply them to the load circuit, so even if the power supply is small or unstable with a single power source. , It becomes possible to supply stable electric power to the load circuit.

100 Power transfer circuit 11 Energy storage circuit 12 Energy supply circuit 13 Reverse bias prevention circuit 14 Load circuit 21 Internal power supply circuit 22 Switching control circuit 200 Power transfer circuit 300 Power transfer circuit 32 Energy supply circuit 35 Control circuit

Claims (9)

A power transfer circuit that supplies power to a load circuit using multiple power sources.
A first power supply line and a second power supply line for supplying power to the load circuit, and
A plurality of first capacitors connected in series between the first power supply line and the second power supply line, each forming a closed circuit with each of the plurality of power supplies via a switch. A first power storage unit having a capacitor group consisting of
A second capacitor including a second capacitor connected in parallel with the capacitor group between the first power supply line and the second power supply line to form a closed circuit with the capacitor group via a switch. Power storage unit and
A power transfer circuit characterized by having. The first power supply line and the second power supply line are connected in parallel with the second capacitor, and the potential between the terminals of the second capacitor becomes a negative potential when viewed from the reference potential. The power transfer circuit according to claim 1, further comprising a reverse bias prevention circuit including a diode that allows a current to flow based on the electric charge stored in the second capacitor. It has a switching control unit that controls on / off switching of the switch of the first power storage unit and the switch of the second power storage unit.
By turning on the switch of the first power storage unit and turning off the switch of the second power storage unit, charges from the plurality of power sources are accumulated in the capacitor group and in the second capacitor. A first charge storage mode that supplies power to the load circuit based on the stored charge,
By turning off the switch of the first power storage unit and turning on the switch of the second power storage unit, the electric charge accumulated in the capacitor group is transferred to the second capacitor group, and the capacitor group A second charge storage mode that supplies power to the load circuit based on the charge stored in
The power transfer circuit according to claim 1 or 2, wherein the circuit state is changed. The switching control unit is between a first charge storage period that controls the circuit state to the first charge storage mode and a second charge storage period that controls the circuit state to the second charge storage mode. The power transfer circuit according to claim 3, further comprising a dead time for controlling both the switch of the first power storage unit and the switch of the second power storage unit to be turned off. The power according to claim 3 or 4, wherein the switching control unit switches on and off the switch of the second power storage unit according to the voltage value of the voltage applied to the load circuit. Transfer circuit. In the second charge storage mode, the second power storage unit boosts the voltage between the terminals of the second capacitor according to the voltage value of the voltage applied to the load circuit to the load circuit. The power transfer circuit according to any one of claims 3 to 5, further comprising a booster circuit for supplying. A plurality of first power supply lines connected in series between the first power supply line and the second power supply line connected to the load circuit, and forming a closed circuit with each of the plurality of power supplies via a switch. A first power storage unit having a capacitor group composed of capacitors is connected in parallel with the capacitor group between the first power supply line and the second power supply line, and the capacitor group and a switch are used. A power transfer circuit having a second power storage unit including a second capacitor forming a closed circuit is a power transfer method for transferring power from the plurality of power sources to the load circuit.
By turning on the switch of the first power storage unit and turning off the switch of the second power storage unit, charges from the plurality of power sources are accumulated in the capacitor group and in the second capacitor. The first step of supplying power to the load circuit based on the stored charge,
By turning off the switch of the first power storage unit and turning on the switch of the second power storage unit, the electric charge accumulated in the capacitor group is transferred to the second capacitor group, and the capacitor group A second step of supplying power to the load circuit based on the charge stored in the
A power transfer method comprising. Between the first step and the second step, a step of turning off both the switch of the first power storage unit and the switch of the second power storage unit is further included. The power transfer method according to claim 7. The first step includes a step of boosting the voltage between terminals of the second capacitor and supplying it to the load circuit according to the voltage value of the voltage applied to the load circuit. Item 7. The power transfer method according to Item 7.

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