JP7020737B1 - Charge control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To construct a buck-boost circuit in which an energization loss can be reduced by a simple circuit and a drive circuit configuration is easy, and a voltage between a DC power supply and a secondary battery can be obtained without causing an extremely narrow pulse width in a switching signal. Provided is a charge control device capable of charge control regardless of the relationship and bidirectional charge / discharge control between a DC power supply and a secondary battery as needed. A charge control system detects an id of a current flowing through an inductor L, an output vc of a PI controller for matching with a reference current Idr, a triangular wave having a minimum value of zero and a peak value of Vp, and this triangular wave. Is compared with a triangular wave whose DC level is shifted by Vp, a switching signal is generated so as not to be less than the minimum pulse width of the switching signal, and the two switches S1 and S2 are driven through the drive circuit Driver. [Selection diagram] FIG. 10

Description

The present invention is a technique relating to a buck-boost circuit capable of charging and controlling a secondary battery having an arbitrary operating voltage from a DC power source and a control method thereof.

Due to the remarkable progress of secondary storage batteries such as lithium-ion batteries in recent years and the development of electronic circuit control technology and power electronics technology, rechargeable electric products have been put into practical use in an extremely wide range of fields from small capacity to large capacity. Has been done.

As a charger for charging the secondary battery, if it has a large capacity, it can be used for charging the secondary battery of an electric vehicle, temporarily storing the generated power from the solar battery, or leveling the generated power. As an emergency power source, there is one that charges a secondary battery.

In particular, in a charge control device for a charging stand of an electric vehicle, it is desired that secondary batteries having various operating voltages can be charged with high efficiency depending on the total number of storage batteries loaded in the electric vehicle. It is necessary to be able to handle a wide range of voltage differences between the final voltage and the final voltage.

On the other hand, in small portable devices that have a small capacity and control the charging and discharging of the secondary battery, the nominal voltage of the secondary battery is fixed in the dedicated charger, but in the case of lithium ion etc., the nominal voltage is relative to the full charge voltage. It is necessary to have a final voltage that can be charged and controlled with high efficiency against changes of about 40%.

When the voltage of the secondary battery for charging is low with respect to the voltage of the DC power supply, it can be charged while controlling the current by the step-down operation, and when it is high, it can be charged while controlling the current by the boosting operation. A charging device that can charge the case is also required.

Therefore, a buck-boost circuit capable of raising / lowering operation and step-down operation is desired as a device that can control charging for a wide range of secondary battery voltages with respect to a DC power source for charging. The pressure circuit is less efficient than a single booster circuit or a single step-down circuit.

Therefore, in contrast to a general step-down circuit that can be configured by connecting a free foiling diode to a circuit that leads to a load via a switch circuit and an inductor in a DC power supply, energy is stored in the inductor after passing through the inductor. A buck-boost circuit having a configuration in which an inductor is shared with a switch circuit for passing a current for the current and a general booster circuit in which a backflow prevention diode is connected from the load side is used.

In addition, the bidirectional charging circuit that can control charging from the secondary battery side to the DC power supply side and discharge control in the secondary battery has a common inductor and is symmetrically opposite to the switch element of the buck-boost circuit. An H-bridge type buck-boost circuit that can be configured by connecting to is also used.

Patent No. 4049333 JP-A-2002-238250 Patent No. 4094649 Patent No. 5211678 Patent No. 5966503 Patent No. 5794982

In the charge control device, it is important to reduce the circuit loss due to the energizing current as much as possible in order to handle a large amount of electric power and effectively utilize the energy of the limited storage battery, and it has been used as a charge control circuit until now. One of the problems in the present invention is to provide a buck-boost circuit configuration that can be reduced as much as possible compared to the existing circuit and that leads to simplification of the drive control circuit of the switch element without complicating the circuit configuration. be.

Next, in the charge control operation by switching control, the flow ratio control of the switching element is generally used, but when the voltage of the DC power supply and the secondary battery for charging are close, the on period or off period of the extremely narrow pulse width is used. The second subject of the present invention is the development of a control method that avoids ultra-narrow pulses, because it becomes an operation and may cause control stability and an increase in loss in the switching element.

Then, when the switching control signal is generated, if it is a control method that selects a step-down operation or a step-up operation depending on the operation relationship between the DC power supply and the secondary battery for charging, the influence of the voltage detection accuracy when switching the control method is affected. The third subject of the present invention is the development of a control method that does not rely on such voltage detection.

Furthermore, not only the charging operation from the DC power supply to the secondary battery for charging, but also the charging that can perform bidirectional current control that can reduce the circuit loss due to the energizing current as much as possible in the circuit that can control the discharge from the secondary battery to the DC power supply side. The development of the circuit is the fourth issue.

(Patent Document 1) is a circuit in which a step-down circuit and a step-up circuit inductor are shared and a step-down chopper circuit and a step-up chopper circuit are combined. Since it can be used, it is used as a general one-way buck-boost control charging circuit.

(Patent Document 2) is a bidirectional buck-boost control charging circuit capable of bidirectional current control by connecting a diode and a switch in a one-way charging circuit in antiparallel to form a symmetrical circuit configuration. It is used as a typical H-bridge type buck-boost circuit.

However, as the buck-boost circuit, the circuit configuration is such that two diode or switch elements are inserted in series in the energization circuit in both the general one-way buck-boost circuit operation and the bidirectional buck-boost circuit operation. Since the energization circuit loss due to the current flowing through these elements becomes the voltage drop and the energization current product of the two elements, it is desired to reduce the number of series elements.

Further, in any of the control methods of (Patent Document 1) to (Patent Document 5), whether to perform a step-down operation or a step-up operation by these buck-boost circuits is selected by detecting the voltage of the secondary battery for charging. A control method is adopted, and except for (Patent Document 5), the voltage of the DC power supply is also detected, and the buck-boost control is selected in comparison with the voltage of the secondary battery for charging, and the voltage described above is selected. It can be said that there remains a problem due to the accuracy of detection.

Further, as a method of generating a switching signal of these step-up / down circuits, (Patent Document 4) and (Patent Document 5) are a PWM switching signal with an error signal from a voltage controller and two comparators using two types of triangular waves. However, the control for avoiding the generation of the narrow pulse width of the PWM switching signal is not described including the cases of (Patent Document 1) to (Patent Document 3).

FIG. 1 shows a buck-boost circuit according to the present invention, in which one end of two switches is commonly connected to the negative side of the DC power supply. In FIG. 2, when the switch S1 is turned on, one end of the two switches is connected to the DC power supply Ed. Is a circuit configuration that is commonly connected to the positive side of the DC power supply.

FIG. 3 shows the step-up / down circuit operation shown in FIG. 1, the current path during the step-down operation and the current path during the step-up operation. The circuits of the operation modes (3) and (4) are formed, but since the operation modes (1) and (4) are the same circuit, the step-up / down operation is between the three operation modes (1) to (3). Will be switch controlled.

As is clear from the figure, in the operation mode (1) in the step-down operation, when the switch S1 is on, the inductor L, the secondary battery EB, the diode D1 and the switch S1 are connected in series from the DC power supply Ed, and the diode D1. And the two elements of the switch S1 are connected in series, but in the operation mode (2), when the switch S1 is turned off, a free foiling circuit can be formed with only one diode D2.

Further, in the operation mode (3) in the boost operation, the number of energizing circuit elements when one switch S2 is turned on can be one while the switch S1 is turned on, and the switch S2 is turned off. In the operating mode (4), the two elements of the diode D1 and the switch S1 are connected in series.

Therefore, in both the step-down operation and the step-up operation, the number of elements at the time of energization can be reduced as compared with a general buck-boost circuit, so that the effect of reducing the circuit loss at the time of energization can be expected.

If NPN transistors, IGBTs, N MOSFETs, etc. are used as switch elements in the circuit shown in FIG. 1, the emitter or source of the two switches and the negative line of the DC power supply can be made common, which simplifies the drive circuit configuration. can.

As described above, the buck-boost circuit of the present invention switches between the three operation modes (1) to (3). Here, the step-down control and the step-up control in the one-way buck-boost control are performed. The flow path is reprinted, and the relationship between the PWM switching pulse width, the DC power supply voltage, and the output voltage is considered based on the operating waveform of the voltage ex across the free foiling diode D2.

FIG. 4 shows the waveform of the flow path and the voltage ex across the diode D2 during step-down control by on / off operation of the switch S1 when the inductor current is continuously flowing in the one-way buck-boost circuit. There is.

で関係づけられる。 If the voltage of the DC power supply is Ed, the voltage of the secondary battery is EB, the switching cycle is T, the ON period of switch S1 is Ton1, and the flow ratio of switch S1 is α1, the average voltage across the inductor is zero. Therefore, since the average voltage of the voltage across the diode D2 ex is equal to the voltage of the secondary battery,

Is related by.

直流電源の電圧と二次電池の電圧EBが近い値のときは、α1は１に近い値となり、スイッチS1のオフ期間Toff1は、極めて狭いパルス幅となる。 Also, let β1 be the ratio of the off period Toff1 of the switch S1 to the switching period T.

When the voltage of the DC power supply and the voltage EB of the secondary battery are close to each other, α1 has a value close to 1, and the off period Toff1 of the switch S1 has an extremely narrow pulse width.

FIG. 5 shows the waveforms of the flow path and the voltage ex across the diode D2 during boost control by on / off operation of the switch S2 when the inductor current is continuously flowing in the one-way buck-boost circuit. There is.

で関係づけられる。 Assuming that the switching cycle is T, the ON period of switch S2 is Ton2, and the flow ratio of switch S2 is α2, the average value of the voltage ex across the diode D2 is the voltage EB of the secondary battery.

Is related by.

In this case, when the voltage of the DC power supply and the voltage EB of the secondary battery are close to each other, α2 becomes a value close to 0, and the ON period Toon2 of the switch S2 has an extremely narrow pulse width.

In this way, when the DC voltage Ed and the voltage EB of the secondary battery are in a close relationship in both the step-down operation and the step-up operation, the switching pulse width of the switch S1 or the switch S2 becomes extremely narrow, and in particular, the switching cycle. When becomes shorter, it becomes difficult to accurately control the flow ratio.

In the present invention, when the DC voltage Ed and the secondary battery voltage EB are close to each other, the step-down operation mode and the step-up operation mode are operated in one switching cycle to prevent the problem of narrow pulse width generation. ..

FIG. 6 shows the waveforms of the flow path due to the on / off operation of the switch S1 and the switch S2 and the voltage ex across the diode D2 when the inductor current in the buck-boost operation is continuously flowing in the one-way buck-boost circuit. Shows.

Assuming that the switching cycle is T, the off period of switch S1 is Toff1, and the on period of switch S2 is Ton2, the following equation can be obtained because the average value of the voltage ex across the diode D2 is EB.

となり等しくなる。 At this time, when the DC voltage Ed and the secondary battery voltage EB are equal, the relationship between the off period Toff1 of the switch S1 and the on period Ton2 of the switch S2 is.

Will be equal.

Therefore, by setting the pulse width of the switch S1 off period Toff1 and the switch S2 on period Ton2 to the minimum pulse width Tmin or more, the problem of extremely narrow pulse in switching control can be solved.

However, although it is close to the DC voltage Ed and the secondary battery voltage EB, there is a voltage difference of ± ΔE with respect to EB (step-down operation when positive (+), boost operation when negative (-)). When

スイッチS2のオンパルス幅Ton2が狭くなるので、最少パルス幅をTminとおくと、 (Ton2>Tmin)を確保する必要があり、スイッチS1のオフパルス幅は

となる。 Therefore, when the voltage deviation of EB with respect to Ed becomes step-down operation (+ ΔE),

Since the on-pulse width Ton2 of the switch S2 becomes narrow, if the minimum pulse width is set to Tmin, it is necessary to secure (Ton2> Tmin), and the off-pulse width of the switch S1 is

Will be.

スイッチS1のオフパルス幅Toff1が狭くなるので、最少パルス幅をTminとおくと、(Toff1>Tmin)を確保する必要があり、スイッチS2のオンパルス幅を決める通流比α2は

となる。 Also, when the voltage deviation of EB with respect to Ed becomes boosting operation (-ΔE),

Since the off-pulse width Toff1 of the switch S1 becomes narrow, if the minimum pulse width is set to Tmin, it is necessary to secure (Toff1> Tmin), and the flow ratio α2 that determines the on-pulse width of the switch S2 is

Will be.

Then, when the voltage deviation of the EB with respect to Ed exceeds (+ ΔE), the switching control signal generation method is switched so as to enter the single step-down operation mode or the single step-up operation mode.

At this time, when the minimum pulse width Tm or more is secured in the off period Toff1 of the switch S1 in the single step-down operation mode,

Also, since the ON period Ton2 of the switch S2 in the single boost operation mode needs to work with the minimum pulse width Tm or more.

From the above, when the pulse width of the switching off signal of the switch S1 in the step-down operation becomes narrow and the minimum pulse width reaches Tm, when the buck-boost operation mode is switched, the pulse width of the switching off signal of the switch S1 becomes 2 Tm. The pulse width during the ON period of switch S2 is Tm, which can prevent the generation of extremely narrow pulses.

In addition, when the pulse width of the switching on signal of the switch S2 in the boost operation becomes narrow and the minimum pulse width becomes Tm, when the buck-boost operation mode is switched, the pulse width of the switching on signal of the switch S2 becomes 2 Tm, and the switch. The pulse width during the on period of S1 is Tm, which can prevent the generation of extremely narrow pulses.

The above has been described when the control system is configured with a one-way buck-boost circuit in order to charge and control the secondary battery for charging from the DC power supply according to the present invention. A discharge control method for extracting electric energy to an external power source will be described.

FIG. 7 shows a charging path from a DC power supply to a secondary battery for charging by forming a symmetric circuit configuration in which the diode and the switch are connected in antiparallel to the switch and the diode in the one-way charging circuit shown in FIG. On the other hand, an example of a main circuit configuration of a bidirectional buck-boost circuit provided with a path for discharge control from the secondary battery to the DC power supply side is shown.

FIG. 8 shows the current path during the step-down operation and the current path during the step-down operation in the charge control operation from the DC power supply to the secondary battery by this bidirectional buck-boost circuit, and shows the operation mode (1) during the step-down operation. , (2), During boosting operation, the circuits of operation modes (3) and (4) are formed, but in this case as well, the operation modes (1) and (4) are the same circuit, so the buck-boost operation is as follows. Switch control is performed between the three operation modes (1) to (3).

The bidirectional buck-boost circuit shown in FIG. 7 can control the discharge from the secondary battery to the DC power supply side, and FIG. 9 shows the current path during the step-down operation and the current path during the step-up operation, and the inductor It can be seen that the flowing current flows in the opposite direction, and a discharge path can be formed from the secondary battery side to the DC power supply side.

Therefore, in the control system using the bidirectional buck-boost circuit shown in FIG. 7, the charge control operation for the secondary storage battery and the discharge control operation by the current control in the opposite direction are easily switched depending on whether the current reference is positive or negative in the current control of the inductor. be able to.

Next, a specific method for generating a switching control signal that does not generate a narrow pulse width in the charge control device of the present invention will be described.

FIG. 10 shows a control system that controls charging from the DC power source Ed to the charging secondary battery EB using the one-way buck-boost control circuit according to the present invention.

In this control system, the output vc of the PI controller for detecting the current id flowing through the inductor L and matching it with the reference current Idr, the triangular wave vtr1 with the minimum value of zero and the peak value of Vp, and this triangular wave with only Vp. By comparing with the DC level-shifted triangular wave Vtr2, the switching signal of the switch S1 and the switch S2 is generated during the single step-down operation or the single step-up operation, but the output vc of the PI controller and the peak value Vp of the triangular wave are generated. When the difference Δv becomes smaller, the magnitude and level of the two triangular waves are shifted and compared with the output of the PI controller, and a switching pulse that causes a step-down operation and a step-up operation is generated within one switching cycle. It is controlled so that it does not become less than the minimum pulse width Tm of the switching signal.

In the figure, as inputs to the triangle wave comparator, the output vc of the PI controller, the triangle wave vt, and the control amount k that determines the degree of overlap between the waveform near the minimum value of the two triangle waves vtr1 and the waveform near the maximum value of vtr2 are used as inputs. It is configured to generate a switching signal and drive two switches S1 and S2 through a drive circuit.

Here, the control amount k is set so that the off period Toff1 of the switch S1 and the on period Ton2 of the switch S2 do not become less than the minimum pulse width Tm during a single step-down operation or step-up operation.

Further, the reference current Idr is calculated and set based on the charge state amount of the secondary battery such as the voltage of the secondary battery for charging, the current flowing in, and the integrated electric energy amount.

In the control system of the buck-boost control circuit of the present invention, the PI for switching the operation modes of the single step-down operation, the single step-up operation, and the step-up / down pressure operation so that the current id flowing through the inductor matches the reference current Idr. Since it can be performed automatically depending on the level of the output vc of the controller, it is not necessary to detect the voltage Ed of the DC power supply or the voltage EB of the secondary electric machine for charging to switch each operation mode, and the voltage detection accuracy. The problem of can be solved.

As a result, the charge control device of the present invention automatically switches between step-down operation, boost-up operation, and buck-boost operation only by the current control system regardless of the magnitude relationship between the DC power supply and the voltage of the secondary battery for charging. It has excellent characteristics that can be used.

11 and 12 show operation waveforms when a switching signal is generated only by a single step-down control operation or a single step-up operation when the DC power supply voltage and the voltage EB of the secondary battery for charging are close to each other.

At this time, if switching control is applied only by a single step-down operation, it can be seen that the off period Toff1 of the switch S1 becomes extremely narrow as shown in FIG.

Further, FIG. 12 shows a control operation waveform when switching control is applied only by a single boosting operation, and shows that the ON period Ton2 of the switch S2 becomes extremely narrow.

On the other hand, FIG. 13 shows a control operation waveform when a step-up / down operation is performed in which a step-up operation pulse and a step-down operation pulse are input within the switching cycle when the DC power supply voltage and the voltage EB of the secondary battery for charging are close to each other. Even if the DC power supply voltage Ed and the charging secondary battery voltage EB are equal, a switching signal with a constant pulse width is generated, and the control system can operate without generating an extremely narrow pulse. I understand.

14 and 15 show the minimum pulse width in the single step-down operation and the single step-up operation by the above-mentioned control amount k that determines the step-up / down pressure operation mode when the DC power supply voltage and the secondary charging voltage are close to each other. An example of the operation waveform when is set is shown.

One-way buck-boost control circuit (negative side common of DC power supply) One-way buck-boost control circuit (common on the positive side of DC power supply) Current path in step-down operation and step-up operation of one-way buck-boost control circuit Energization path and operation waveform during step-down operation of one-way buck-boost control circuit Energization path and operation waveform during boost operation of one-way buck-boost control circuit Energization path and operation waveform during buck-boost operation of one-way buck-boost control circuit Bidirectional buck-boost control circuit Energization path during charge control of the bidirectional buck-boost control circuit Energization path during discharge control of the bidirectional buck-boost control circuit Charge control system with one-way buck-boost circuit Switching pulse waveform during single step-down operation Switching pulse waveform during single boost operation Switching pulse waveform during buck-boost operation Switching pulse waveform during buck-boost combination control step-down operation Buck-boost combination control Switching pulse waveform during boost-up operation Configuration example of one-way buck-boost control circuit using semiconductor switching elements (IGBT, MOSFET) Configuration example of bidirectional buck-boost control circuit using IGBT switch Example of application circuit as a current source of a uniform charging circuit of a one-way buck-boost control circuit Example of Charge Control System of One-way Buck-Boost Circuit by MOSFET Switch Simulation conditions and circuit (a) Secondary battery, (b) Resistive load Simulation waveform under step-down operation conditions (Ed = 100V, EB = 96V) Simulation waveform under boosted operating conditions (Ed = 100V, EB = 104V) Simulation waveform under buck-boost operating conditions (Ed = 100V, EB = 100V) Simulation waveform at resistance load (R = 10ohm) for output voltage reference change (0 to 200V)

FIG. 16 is a specific implementation circuit configuration example of the buck-boost circuit shown in FIG. 1 according to the present invention, FIG. 16A is a circuit example using an IGBT as a switch element, and FIG. 16B is an N MOSFET. An example of a circuit using the above is shown.

As shown in the figure, when two IGBTs are used as semiconductor switches, the emitter can be connected to the negative side of the DC power supply in common, and when two N MOSFETs are used, both sources can be connected to the negative side of the DC power supply. It will be easy.

FIG. 17 is an example of an implementation circuit in which four switches of the bidirectional buck-boost circuit shown in FIG. 7 according to the present invention are configured by an IGBT, and a switching leg in which a switching arm connected in anti-parallel to the IGBT is connected in series is shown. It can be configured by using two.

The secondary battery charge control device according to the present invention can be used to charge a small-capacity storage battery such as a small portable device, or even if a large number of secondary storage battery cells are connected in series, the assembled storage battery or the secondary storage battery cell is separately charged separately. It is also suitable for the purpose of batch charge control, such as when management control is performed.

An application example of the charging device of the present invention is shown when a management control means for a secondary battery cell is required.

(Patent Document 6) has a simplified main circuit configuration for charging a secondary battery in a built-in storage battery unit for the purpose of uniform charge / discharge control in a built-in storage battery unit when a large number of secondary storage batteries are connected in series. After performing a control committee, batch charging control is performed.

FIG. 18 shows, as one of the application examples of the one-way buck-boost charging device of the present invention in such a case, mainly when used as a charging current source for a secondary storage battery shown in (Patent Document 6). The circuit configuration is shown.

FIG. 19 shows a PI controller output in which the switch of the one-way buck-boost control circuit according to the present invention is configured by using NMOS FTE and the current flowing through the inductor matches the reference current, and two sets of triangular waves that do not generate a narrow pulse. In comparison, it is a control system in which a voltage control loop of a secondary storage battery for charging is added to the control system shown in FIG. 10 that generates a switching signal for each switch element.

Here, the reference value of the current flowing through the inductor is such that the output of the PI controller is obtained from the output via the saturation circuit so that the voltage of the secondary storage battery for charging matches the charge completion voltage reference, and is excessive due to the saturation circuit. After charging while suppressing the current, the secondary battery can be floatingly charged at the charge completion voltage.

As an embodiment of the present invention, FIG. 20 shows a main circuit configuration and circuit conditions for which operation confirmation was performed by simulation analysis.

Fig. (A) shows the circuit conditions in the simulation analysis from the DC voltage source (Ed = 100V) to the secondary storage battery voltage (EB-100V ± 4V), and Fig. (B) shows the resistance load (R-10). For ohm), the circuit conditions in the simulation analysis when the reference value Vor of the output voltage is changed in a ramp shape from 0 to 200V are shown.

FIGS. 21 and 22 show the operating waveforms when the voltage of the DC power supply is constant at Ed-100V and the voltage of the secondary battery for charging is 96V and 104V. The former shows Ed (100V)> EB (96V). ), And the current id of the inductor can be automatically controlled to a constant reference value (Idr = 20A) by a single step-down operation, and the latter is automatically because Ed (100V) <EB (104V). It can be confirmed that the step-up operation is performed independently.

On the other hand, FIG. 23 shows the operation waveform when the DC power supply voltage Ed and the voltage EB of the secondary battery for charging are both 100 V, and the buck-boost operation is automatically performed without generating a narrow pulse width as a switching signal. It can be seen that the current id of the inductor can be controlled to a constant reference value (Idr = 20A) by shifting to the mode.

In FIG. 24, in order to confirm a large output voltage control operation instead of the secondary battery, a resistance load (R = 10 ohm) was connected and the reference value of the output voltage was changed significantly from 0 to 200 V. It is an operation waveform at the time, and it is that the output voltage vo can rise along the reference value while the output voltage is around 100V and the step-down operation automatically shifts to the step-up operation via the step-up / down operation. You can check it.

The current id of the inductor is changing because the reference value is determined by the controller of the output voltage, and it is the voltage for a certain resistance load that suddenly increases in the boost operation. This is because the power consumption of the load is proportional to the square of the output voltage.

100 ... DC power supply 200 ... Buck-boost control circuit 300 ... Secondary battery 400 ... Control system unit 410 ... Triangle wave comparison switching signal generation unit 420 ... Current control unit 430 ... Voltage control unit

Claims (5)

A circuit that connects an inductor, a secondary battery, a first diode, and a first switch in series from one end of the DC power supply to return to the other end of the DC power supply, and a second diode is the secondary battery and the first. A circuit that connects the connection point of the diode and the connection point of the DC power supply and the connection point of the inductor, and further, the second switch of the connection point of the inductor and the secondary battery, the DC power supply, and the first switch. A buck-boost circuit is configured by a circuit connected between the connection points, and the flow width of the first switch and the second switch is controlled so that the current flowing through the inductor matches the reference current value. By
The number of series elements of diodes and switches in the current flow path during buck-boost control operation has been reduced, and the drive circuit configuration of both switches has been simplified by allowing the first switch and the second switch to be connected in common. A charge control device capable of controlling charging from the DC power supply to the secondary battery regardless of the magnitude relationship between the DC power supply and the voltage of the secondary battery.
As a switching control method in the charge control device according to claim 1,
When the voltage of the DC power supply is higher than that of the secondary battery to be charged, the second switch is turned off, and the current control of the inductor is performed by step-down operation according to the flow width of the first switch.
When the voltage of the DC power supply is lower than that of the secondary battery to be charged, an on signal is given to the first switch, and the current control of the inductor is performed by boosting operation by the flow width of the second switch.
When the voltage of the DC power supply is close to that of the secondary battery to be charged, a step-up / down operation in which the flow widths of the first switch and the second switch are synchronized with each other to provide a step-up operation period and a step-down operation period. By controlling the current of the inductor with
A charge control device characterized in that the secondary battery can be charged and controlled without a switching control operation having an extremely narrow pulse width.
As a method of generating a switching control signal in the charge control device according to claims 1 to 2, the current flowing through the inductor is also the voltage of the secondary battery for charging, the current flowing in, and the state of the secondary battery which is the integrated power amount. Comparison between the maximum value of the triangular wave whose minimum value is zero and the output of the PI controller to match the reference current value set in and, and the two triangular waves where the minimum value of the triangular wave obtained by DC-shifting the triangular wave is the same. When a switching signal for the first switch and the second switch is generated based on the signal,
When the output level of the PI controller is close to the DC shift level, the amplitudes of the two triangle waves to be compared are slightly increased so that the maximum value of one triangle wave and the minimum value of the other triangle wave are slightly overlapped. Therefore, the charge control device is characterized in that the secondary battery can be charged and controlled without generating a switching signal having an extremely narrow pulse width.
In the charge control device according to claim 1, a third switch is connected to the first diode in antiparallel, a third switch is connected to the first switch in antiparallel, and a fourth switch is connected to the second diode in antiparallel. As a circuit configuration to connect
The first aspect of claim 1, wherein the secondary battery can be charged and controlled from the DC power supply by controlling the flow width of the first switch and the second switch with the third switch and the fourth switch turned off. In addition to the operation of, the first switch and the second switch are turned off, and the flow of the third switch and the fourth switch so that the current flowing through the inductor matches the reference current value. By controlling the width
A charge control device characterized in that the current can be controlled from the secondary battery to the DC power source.
In the charge control device according to claim 4, the charge control technique from the DC power supply side to the secondary battery side according to claims 2 to 3 is performed by exchanging the correspondence between the DC power supply and the secondary battery. By configuring a control system so that the current can be controlled from the secondary battery side to the DC power supply side and switching the polarity of the reference current, charge control from the DC power supply to the secondary battery side and the secondary battery can be performed. A charge control device characterized in that the charge control from the battery to the DC power supply side can control the current in both directions.

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