JP7127453B2 - charge control circuit - Google Patents

Description

The present invention relates to a charging control circuit that controls charging operation from a power supply device to a battery.

As a charging control circuit of this type, a control circuit (charging control circuit) for a charging device disclosed in Patent Document 1 below is known. This charge control circuit controls on/off of two FETs arranged in one of a pair of connection lines connecting a charging device and a secondary battery (battery), and the two FETs. and a control circuit. These two FETs are composed of p-channel enhancement type field effect transistors and are arranged on one connection line in a back-to-back connection state in which the source terminals are connected to each other. A diode is connected in parallel to each FET with the cathode terminal connected to the source terminal and the anode terminal connected to the drain terminal. One of the parallel circuits of the FET and the diode provided on the secondary battery side is used for charging control of the secondary battery, and the other parallel circuit of the FET and the diode is used for preventing discharge of the secondary battery. be. In this charging control circuit, the control circuit measures and compares the voltage output from the charging device (the charging voltage applied to the secondary battery via two FETs) and the battery terminal voltage of the secondary battery, and , determines whether to continue the charging process (control the two FETs to the ON state) or terminate the charging process (control the two FETs to the OFF state) according to the comparison result.

Japanese Patent Application Laid-Open No. 9-275639 (pp. 6-10, FIG. 1)

However, the conventional charging control circuit described above has the following problems. Specifically, in this charging control circuit, the control circuit is directly connected to the output terminal connected to the anode of the secondary battery through a connection line for voltage detection in order to measure the battery terminal voltage. (That is, the configuration is such that the control circuit is always connected to the secondary battery via the connection line). Therefore, in this charge control circuit, even when the two FETs are controlled to be off, a small current (dark current) constantly flows from the secondary battery to the control circuit through the connection line. Therefore, this charge control circuit has a problem to be solved that the secondary battery is wastedly discharged by the current flowing into the control circuit via the connection line for voltage detection.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a main object of the present invention is to provide a charge control circuit capable of preventing wasteful discharge of a battery while the charging operation is stopped.

In order to achieve the above object, a charge control circuit according to the present invention comprises a reverse connection protection element and a current control element arranged in series with a plus side power supply line connecting a power supply device and a battery, and a current detection unit that detects the magnitude of discharge current from the battery to the power supply device via the power supply line and outputs a detection signal based on the detection result; and an output of the detection signal from the current detection unit. At least the current control element out of the reverse connection protection element and the current control element driven to the ON state allowing the bidirectional passage of the current when the current is detected is turned off to prevent the passage of the discharge current. wherein the reverse connection protection element and the current control element are arranged such that the current control element is located on the battery side with respect to the reverse connection protection element. The current detection unit detects the magnitude of the discharge current based on the potential difference across the reverse connection protection element detected through a pair of detection lines connected to one end and the other end of the reverse connection protection element. is detected, and in a charging state in which a charging current is supplied from the power supply device to the battery via the power supply line, the magnitude of the discharging current is equal to or greater than a predetermined low-side current threshold. The detection signal is output when the detection result is obtained.

A charging control circuit according to the present invention includes a current control element disposed on a positive power line of positive and negative power lines connecting a power supply device and a battery, and the negative power line. a current detection unit that detects the magnitude of a discharge current from the battery to the power supply device via the power supply line and outputs a detection signal based on the detection result; At least the current control element out of the reverse connection protection element and the current control element driven to an ON state allowing bidirectional passage of current when the output of the detection signal from the current detection unit is detected and a control unit that drives the discharge current to an OFF state that prevents passage of the discharge current, wherein the current detection unit includes a pair of terminals connected to one end and the other end of the reverse connection protection element. The magnitude of the discharge current is detected based on the potential difference across the reverse connection protection element detected via the detection line, and the charging current is supplied from the power supply device to the battery via the power supply line. The detection signal is output when the detection result indicates that the magnitude of the discharge current is equal to or greater than a predetermined low-side current threshold in the charged state.

According to these charge control circuits, when the power supply is operating normally and the DC voltage output from the power supply is higher than the charging voltage of the battery, the reverse connection protection element and the current control element are turned on. The power supply supplies charging current to the battery from the power supply (performs the charging operation to the battery), and trouble occurs on the power supply side, and the output DC voltage becomes lower than the battery charging voltage, causing discharge. When current occurs, the reverse connection protection device and the current control device can be driven into an off state to quickly prevent discharge from the battery to the power supply. In the charging control circuit, the current detector detects the magnitude of the discharge current based on the potential difference across the reverse connection protection element detected through a pair of detection lines connected to one end and the other end of the reverse connection protection element. Since the configuration is for detection, neither the current detection section nor the control section is directly connected via a wire to a portion between the battery and the current control element on the plus side power supply line. Therefore, according to this charge control circuit, in a state in which the reverse connection protection element and the current control element are driven to the OFF state to prevent discharge from the battery to the power supply, the charge control circuit (specifically, Since generation of a very small current (dark current) flowing into the current detection unit and control unit) can be avoided, it is possible to completely prevent (prevent) battery discharge.

A charging control circuit according to the present invention includes a temperature detection unit that detects the temperature of the reverse connection protection element and outputs a temperature detection signal indicating the temperature, and and a correction unit that lowers the low-side current threshold when the current is low.

In a configuration where the low-side current threshold is constant regardless of changes in the temperature of the reverse connection protection element, the discharge current detection sensitivity decreases when the on-resistance of the reverse connection protection element (usually a MOSFET) decreases as the temperature drops. However, according to this charge control circuit, when the temperature of the reverse connection protection element is lower than a predetermined temperature, the correction unit lowers the low-side current threshold, so the discharge current detection sensitivity is reduced. can be prevented from decreasing.

In the charging control circuit according to the present invention, the correction section increases the low-side current threshold when the temperature indicated by the temperature detection signal is higher than the predetermined temperature.

According to this charging control circuit, when the temperature of the reverse connection protection element is higher than a predetermined temperature, the correction unit increases the low-side current threshold. Variation in the detection sensitivity of discharge current generation can be greatly reduced.

In the charging control circuit according to the present invention, the current detection unit detects that the magnitude of the discharge current is on the low side in a discharge state in which the discharge current is supplied from the battery to the power supply device via the power supply line. Outputting the detection signal when the detection result is equal to or higher than a predetermined high-side current threshold higher than the current threshold.

According to this charge control circuit, the power supply operates normally (current output to the battery side) when the power supply is a bidirectional converter that charges the battery and discharges the battery. When the output DC voltage is higher than the charging voltage of the battery in the operating state, the reverse connection protection element and the current control element are driven to the ON state to supply the charging current from the power supply to the battery. (charging the battery), a problem occurs on the power supply side, the output DC voltage becomes lower than the charging voltage of the battery, and a discharge current occurs, the reverse connection protection element and current control element can be driven off to quickly prevent discharge from the battery to the power supply. In addition, when the power supply is operating normally (current input operation from the battery), the reverse connection protection element and the current control element are driven to the ON state to supply discharge current from the battery to the power supply ( discharge operation), and when a problem occurs on the power supply side and the discharge current reaches the high side current threshold (e.g., the maximum discharge current value of the battery), the reverse connection protection device and current control device are driven to the OFF state. to stop discharging the battery to the power supply.

According to the present invention, a minute current (dark current) flows from the battery to the charge control circuit in a state in which the reverse connection protection element and the current control element are driven to the off state to prevent discharge from the battery to the power supply device. can be avoided, completely preventing wasteful discharge of the battery.

2 is a configuration diagram showing the configuration of a charging control circuit 1A; FIG. 3 is a configuration diagram showing a configuration of a charging control circuit 1B including a temperature detection section 31; FIG. 4 is a configuration diagram showing the configuration of charging control circuit 1C when converter 41 is a bidirectional converter; FIG. 3 is a configuration diagram showing the configuration of a charging control circuit 1D; FIG.

Embodiments of a charging control circuit will be described below with reference to the accompanying drawings. In this example, as an example, a charge control circuit connected to a power supply line connecting a converter as a power supply device and a battery to control charging of the battery by the converter will be described.

First, the configuration of the charge control circuit 1A as a charge control circuit will be described with reference to the drawings.

As shown in FIG. 1, the charging control circuit 1A includes a pair of first terminals 2a and 2b (also referred to as "first terminals 2" when not distinguished), a pair of second terminals 3a and 3b (when not distinguished). , also referred to as “second terminal 3”), reverse connection protection element 4, current control element 5, current detection unit 6, and control unit 7, DC voltage output from converter 41 connected to first terminal 2 Based on V1, the charging operation of outputting (supplying) the charging current I1 to the battery 42 connected to the second terminal 3 to charge the battery 42 is executed.

Specifically, the first terminal 2a of the first terminals 2a and 2b is connected to one output terminal (plus terminal) of the pair of output terminals of the converter 41, and the first terminal 2b is connected to the converter 41. is connected to the other output terminal (negative terminal) of the The second terminal 3 a of the second terminals 3 a and 3 b is connected to the anode of the battery 42 and the second terminal 3 b is connected to the cathode of the battery 42 .

The reverse connection protection element 4 and the current control element 5 connect the power supply line connecting the converter 41 and the battery 42 (in this example, the first terminal 2a connected to the converter 41 and the second terminal 3a connected to the battery 42). are connected in series to the plus side power supply line La). In this example, the reverse connection protection element 4 is composed of a parallel circuit of an n-type MOSFET (metal-oxide-semiconductor field-effect transistor) 4a and a diode 4b connected in parallel thereto, and the current control element 5 is , an n-type MOSFET 5a and a parallel circuit of a diode 5b connected in parallel thereto. In this case, each diode 4b, 5b is connected in parallel with the corresponding n-type MOSFET with the anode terminal connected to the source terminal of the corresponding n-type MOSFET and the cathode terminal connected to the drain terminal of the corresponding n-type MOSFET. It is connected.

Further, the reverse connection protection element 4 and the current control element 5 are arranged in a state where the current control element 5 is located on the battery 42 side (the second terminal 3 side) with respect to the reverse connection protection element 4 and the reverse connection protection element 4 and the current control element 5, the source terminals of the n-type MOSFETs 4a and 5a are connected to each other (back-to-back connection). In addition, each diode 4b, 5b can be substituted with the body diode of the corresponding n-type MOSFET. becomes.

In addition, the reverse connection protection element 4 is in a state where the charging control circuit 1A is stopped (that is, when the n-type MOSFET 4a of the reverse connection protection element 4 is in an off state), and the battery 42 is connected between the second terminals 3 in reverse polarity. When the reverse connection protection element 4 is in the ON state (the n-type MOSFET 4a of the reverse connection protection element 4 is in the ON state), the magnitude (current value) of the discharge current I2 flowing It has a function (current detection function) to generate a corresponding potential difference Vds between both ends (between drain and source terminals).

As shown in FIG. 1 as an example, the current detection unit 6 includes a potential difference detection unit 21 and a comparison unit 22, and detects a discharge current I2 from the battery 42 to the converter 41 via the power supply lines La and Lb. Along with detecting the size, based on the result of this detection (detection result), a detection signal S1 is generated and output to the control section 7 .

Specifically, the potential difference detection unit 21 is composed of an operational amplifier (not shown) or the like, and a pair of They are connected via detection lines Ls1 and Ls2. In addition, the potential difference detection unit 21 amplifies the potential difference Vds between both ends of the reverse connection protection element 4 (between the drain and source terminals of the n-type MOSFET 4a) and outputs a current whose voltage value changes in proportion to the potential difference Vds. It outputs the detection signal Vi. This potential difference Vds becomes a positive (plus) voltage when the potential of the other end (source terminal) of the reverse connection protection element 4 is higher than the potential of one end (drain terminal) of the reverse connection protection element 4. When the other terminal (source terminal) is at a low potential with respect to the potential of , it becomes a negative (negative) voltage.

Normally, in the ON state (operating state in the saturation region), the on-resistance of an n-type MOSFET is a sufficiently low constant value, and it allows current to pass in both directions (direction from the drain terminal to the source terminal). , and in the direction from the source terminal to the drain terminal). Therefore, the potential difference Vds (voltage drop) generated across the terminals of the n-type MOSFET 4a (between the drain and the source terminal) due to the current flowing from the source terminal to the drain terminal in the ON state is the voltage drop of the diode 4b. It becomes a positive voltage that is lower than the forward voltage and that changes in proportion to the magnitude of the current. Therefore, the potential difference detection unit 21 substantially detects the magnitude of the discharge current I2 (the current flowing from the battery 42 toward the converter 41, which is the opposite of the charge current I1) based on the potential difference Vds. A current detection signal Vi (a signal indicating the magnitude of the discharge current I2) whose voltage value changes in proportion to the magnitude of the discharge current I2 is output.

The comparison unit 22 is composed of, for example, a comparator, and compares the current detection signal Vi output from the potential difference detection unit 21 with a predetermined current threshold value Vth (predetermined current value discharge current I2 is in an on-state reverse connection). voltage value corresponding to the potential difference Vds generated when flowing through the protective element 4), and the magnitude of the current detection signal Vi is equal to or greater than this current threshold value (that is, the magnitude of the discharge current I2 is defined in advance). When the comparison result (detection result) indicates that the current value is greater than or equal to the current value, a detection signal S1 indicating this comparison result is output to the control unit 7 .

In this example, as an example of the current threshold Vth, in a charging state in which the charging current I1 is supplied from the converter 41 to the battery 42 via the power supply lines La and Lb, for example, the converter 41 side (the converter 41 itself or the converter 41 The discharge current I2 generated when the DC voltage V1 drops below the charging voltage V2 of the battery 42 due to some trouble occurring in the external power supply that supplies power to the battery 42 is detected by the current detection unit 6 from a state of a low current value. A current threshold (low-side current threshold Vth1) for a low voltage value (zero volts or a low voltage value close to zero volts) is defined so that it can be detected by .

The control unit 7 includes, for example, a processing circuit including a CPU and memory, and a drive circuit (both not shown) for driving the n-type MOSFETs 4a and 5a. In this example, as an example, the control unit 7 determines that the content of the operation instruction Ss input from an input unit (keyboard, operation panel, etc.) (not shown) disposed inside or outside the charging control circuit 1A indicates that the charging operation is to be performed. When it indicates, the charging control circuit 1A is operated in the charging state.

Further, in this charging state, the control unit 7 permits current to pass in both directions when detecting the output of the detection signal S1 from the current detection unit 6 (that is, either the charging current I1 or the discharging current I2 Of the n-type MOSFETs 4a and 5a of the reverse connection protection element 4 and the current control element 5, which were driven to the ON state, at least the n-type MOSFET 5a of the current control element 5 (in this example, the reverse connection protection element The n-type MOSFETs 4a, 5a) of both 4 and current control element 5 are driven to the off state preventing the passage of discharge current I2.

In addition, in the control unit 7, as shown in FIG. 1, the drive circuit is connected to the source terminals of the respective n-type MOSFETs 4a and 5a constituting the reverse connection protection element 4 and the current control element 5 via one common drive line Ld1. , and connected to the gate terminals of the n-type MOSFETs 4a and 5a through one common drive line Ld2. Further, the drive circuit is controlled by the processing circuit, and when each of the n-type MOSFETs 4a and 5a constituting the reverse connection protection element 4 and the current control element 5 is shifted to the ON state (operation state in the saturation region), the gate When the drive voltage Vdv having a voltage value exceeding the threshold voltage value is output between the drive lines Ld1 and Ld2 and the respective n-type MOSFETs 4a and 5a are shifted to the off state, the output of the drive voltage Vdv is stopped (the voltage of the drive voltage Vdv value below the gate threshold voltage value).

From the above, in the charging control circuit 1A, both the current detection unit 6 and the control unit 7 have a current between the second terminal 3a in the power supply line La and the drain terminal of the n-type MOSFET 5a that constitutes the current control element 5. It is configured so that it is not directly connected to the part of through the wiring.

Next, the operation of the charging control circuit 1A will be described with reference to the accompanying drawings. It is assumed that the converter 41 is connected to the first terminal 2 and the battery 42 is connected to the second terminal 3 . It is also assumed that the DC voltage V1 output from the converter 41 during normal operation is set to a voltage higher than the charging voltage V2 of the battery 42 in the fully charged state.

In this state, when an operation instruction Ss indicating a charging operation is input, in the control unit 7, the processing circuit controls the driving circuit to apply the driving voltage Vdv having a voltage value exceeding the gate threshold voltage value to the driving line. Output between Ld1 and Ld2. As a result, the reverse connection protection element 4 and the current control element 5 (each of the n-type MOSFETs 4a and 5a constituting them) are both turned on (a state in which bidirectional passage of current is allowed).

Therefore, when the converter 41 is operating normally, the output DC voltage V1 is higher than the charging voltage V2 of the battery 42. Therefore, the charging control circuit 1A controls the reverse connection protection element 4 in the ON state and the current control circuit 1A. A charging current I1 is supplied from the converter 41 to the battery 42 via the n-type MOSFETs 4a and 5a of the element 5 (the battery 42 is charged). In this case, the potential difference Vds detected by the potential difference detection unit 21 of the current detection unit 6 becomes a negative voltage, so that the current detection signal Vi also becomes a negative voltage (less than the low-side current threshold Vth1). Therefore, the comparator 22 stops outputting the detection signal S1 to the controller 7 . Therefore, control unit 7 continues to output drive voltage Vdv to n-type MOSFETs 4a and 5a of reverse connection protection element 4 and current control element 5, so that the operation of charging battery 42 continues.

In this charging state, if some trouble occurs on the converter 41 side and the DC voltage V1 drops below the charging voltage V2 of the battery 42, the reverse connection protection element 4 and the current control element 5 in the on state A discharge current I2 flowing from the battery 42 to the converter 41 flows (is generated) in the n-type MOSFETs 4a and 5a. In this case, the potential difference Vds detected by the potential difference detection section 21 of the current detection section 6 becomes a positive voltage, so that the current detection signal Vi also becomes a positive voltage.

In this example, as described above, the current threshold value of the low voltage value (low side current threshold value Vth1) is defined so that the current detection unit 6 can detect the generation of the discharge current I2 from the state of the low current value. ing. Therefore, when the discharge current I2 with a low current value is generated, the positive voltage current detection signal Vi reaches the low-side current threshold Vth1. Thereby, the comparator 22 outputs the detection signal S1 to the controller 7 . Further, the control unit 7 detects the output of the detection signal S1 from (the comparison unit 22 of) the current detection unit 6, and determines the drive voltage Vdv for each of the n-type MOSFETs 4a and 5a of the reverse connection protection element 4 and the current control element 5. The output is stopped and this stopped state is continued. Therefore, each n-type of the reverse connection protection element 4 and the current control element 5 that have been driven in an ON state that allows bidirectional passage of current (that is, allows passage of both the charging current I1 and the discharging current I2) MOSFETs 4a and 5a are driven to an off state preventing the passage of current in both directions. This prevents discharge from battery 42 to converter 41 when trouble occurs.

As described above, according to the charging control circuit 1A, when the converter 41 is operating normally and the output DC voltage V1 is higher than the charging voltage V2 of the battery 42, the reverse connection protection element 4 and the current control The element 5 is driven to the ON state, the charging current I1 is supplied from the converter 41 to the battery 42 (the battery 42 is charged), trouble occurs on the converter 41 side, and the output DC voltage V1 becomes When the charging voltage V2 of the battery 42 becomes lower than the discharge current I2 and the discharge current I2 is generated, the reverse connection protection element 4 and the current control element 5 are driven to the OFF state to quickly prevent discharge from the battery 42 to the converter 41. can be done. In addition, in the charge control circuit 1A, as described above, both the current detection unit 6 and the control unit 7 connect the second terminal 3a in the power supply line La on the positive side and the drain terminal of the n-type MOSFET 5a constituting the current control element 5. and are not directly connected via wiring to the part between them. Therefore, according to this charge control circuit 1A, in a state in which the reverse connection protection element 4 and the current control element 5 are driven to the OFF state to prevent discharge from the battery 42 to the converter 41, the charge control circuit Since generation of a minute current (dark current) flowing into 1A (specifically, the current detection unit 6 and the control unit 7) can be avoided, useless discharge of the battery 42 can be completely prevented (prevented).

In this charging control circuit 1A, the magnitude of the discharge current I2 is determined by the potential difference Vds generated across the reverse connection protection element 4 (between the drain and source terminals of the n-type MOSFET 4a). A voltage determined by the current value of I2) is adopted, but the on-resistance of the MOSFET changes with the temperature of the MOSFET (specifically, the temperature characteristic with a positive temperature coefficient )have. Therefore, when the temperature of the MOSFET is higher than the standard temperature (for example, about 30° to 40°), the on-resistance becomes higher, which improves the detection sensitivity of the discharge current I2 (lower current value). At the discharge current I2, the current detection signal Vi exceeds the low-side current threshold Vth1), so no problem occurs. (The current detection signal Vi does not exceed the low-side current threshold Vth1 unless the discharge current I2 having a higher current value is generated).

In order to avoid this problem, the charging control circuit 1B shown in FIG. When the temperature indicated by the signal Vtp is higher than the standard temperature (predetermined temperature: 30°, for example), the temperature indicated by the temperature detection signal Vtp is set to the standard temperature without changing the low-side current threshold Vth1. When the temperature is lower than the standard temperature, the correction unit (in this example, the control unit 7 is configured to also serve as the correction unit) that lowers the low-side current threshold Vth1 from the value at the standard temperature by the temperature drop from the standard temperature. but may be separate from the control unit 7). The same components as those of the charging control circuit 1A shown in FIG.

According to the charging control circuit 1B with this configuration, the temperature of the reverse connection protection element 4 is lower than the standard temperature, the on-resistance of the n-type MOSFET 4a is lower, and the current value is the same as at the standard temperature. When the potential difference Vds when the discharge current I2 flows is also low, the low-side current threshold Vth1 is lowered by that amount, so when the temperature of the reverse connection protection element 4 drops below the standard temperature Prevents the above-mentioned problem (problem that the detection sensitivity of the discharge current I2 is lowered (the current detection signal Vi does not exceed the low-side current threshold Vth1 unless the discharge current I2 with a higher current value is generated)). can do.

Furthermore, in this charge control circuit 1B, when the temperature indicated by the temperature detection signal Vtp is higher than the standard temperature (predetermined temperature: 30° in this example), the correction unit It is also possible to employ a configuration in which the low-side current threshold Vth1 is raised from the value at the standard temperature by the temperature rise. According to the charge control circuit 1B having this configuration, the current value of the discharge current I2 at which the comparison unit 22 starts outputting the detection signal S1 to the control unit 7 varies (discharge current variation in the detection sensitivity of I2 generation) can be greatly reduced.

In addition to the function of converting the power supplied from the external power source into a DC voltage V1 and outputting it to the battery 42, the converter 41 converts the charging voltage V2 of the battery 42 into a DC voltage and converts it into a DC voltage (not shown). In a configuration having a function of outputting to an external device (a configuration in which converter 41 is a bi-directional converter), charging control circuits 1A and 1B perform a charging operation of supplying charging current I1 from converter 41 to battery 42 from battery 42 to converter 41. In addition to the above-described configuration in which the discharge current I2 is detected and executed while detecting whether or not the discharge current I2 is generated, the discharge operation of supplying the discharge current I2 from the battery 42 to the converter 41 is performed with a predetermined current value of the discharge current I2. It is preferable to provide a new configuration that detects the occurrence of the discharge current I2 exceeding the value (discharge current I2 becomes too large).

A charging control circuit 1C having these two configurations will be described with reference to FIG. As an example, the charging control circuit 1C adopts a configuration based on the charging control circuit 1B shown in FIG. 2. Although not shown, a configuration based on the charging control circuit 1A shown in FIG. can also be adopted. Also, the same reference numerals are assigned to the same configurations as those of the charge control circuit 1B, and overlapping descriptions are omitted, and different configurations will be mainly described.

The controller 7 operates the charging control circuit 1C in the charging state when the content of the operation instruction Ss input from the input section (not shown) indicates the charging operation. At this time, the controller 7 defines the low-side current threshold Vth<b>1 as the current threshold Vth used in the comparator 22 . Further, when the content of the input operation instruction Ss indicates a discharging operation, the charging control circuit 1C is operated in a discharging state. In this case, the control unit 7 sets the current threshold Vth used in the comparison unit 22 to a current threshold having a voltage value higher than the low-side current threshold Vth1 (high-side current threshold) instead of the low-side current threshold Vth1. Vth2). The controller 7 stores in advance the low-side current threshold Vth1 and the high-side current threshold Vth2.

Since the battery 42 may have a maximum discharge current value defined in the product specifications, the discharge current I2 must be suppressed to this current value or less. Therefore, the high-side current threshold value Vth2 is set to be the same as the voltage value of the current detection signal Vi output from the potential difference detection section 21 when the discharge current I2 of this current value flows through the reverse connection protection element 4. Predefined.

Next, the operation of this charging control circuit 1C will be described.

First, when the charging control circuit 1</b>C is caused to perform the charging operation, an operation instruction Ss indicating the charging operation is input to the control section 7 . At this time, the control unit 7 defines the low-side current threshold value Vth1 for the comparison unit 22 as the current threshold value Vth used in the comparison unit 22 . As a result, the controller 7 causes the charging control circuit 1C to operate in the charging state in the same manner as the charging control circuit 1A. That is, the charging control circuit 1</b>C performs the charging operation of supplying the charging current I<b>1 from the converter 41 to the battery 42 while detecting whether or not the discharging current I<b>2 is generated from the battery 42 to the converter 41 .

Next, when the charging control circuit 1</b>C is to perform a discharging operation, an operation instruction Ss indicating a discharging operation is input to the control section 7 . At this time, the control unit 7 specifies the high-side current threshold Vth2 for the comparison unit 22 as the current threshold Vth used in the comparison unit 22, and operates the charging control circuit 1C in the discharging state. That is, the charge control circuit 1C performs the discharge operation of supplying the discharge current I2 from the battery 42 to the converter 41 while detecting whether or not the discharge current I2 has reached the maximum discharge current value of the battery 42 .

In this state, when the current value of the discharge current I2 is less than the maximum discharge current value of the battery 42, the potential difference Vds detected by the potential difference detection portion 21 of the current detection portion 6 is a positive voltage. Since it is lower than the potential difference Vds when the current I2 flows, the current detection signal Vi output from the potential difference detector 21 is also a positive voltage less than the high-side current threshold Vth2. Therefore, the comparator 22 stops outputting the detection signal S1 to the controller 7 . Therefore, control unit 7 continues to output drive voltage Vdv to each of n-type MOSFETs 4a and 5a of reverse connection protection element 4 and current control element 5, so that battery 42 continues to discharge.

During this discharge operation, if the discharge current I2 increases and reaches the maximum discharge current value of the battery 42 due to some trouble occurring on the converter 41 side, for example, the potential difference Vds detected by the potential difference detection unit 21 reaches this maximum value. It reaches the potential difference Vds when the discharge current I2 of the discharge current value flows. Further, the current detection signal Vi output from the potential difference detection section 21 also reaches the high side current threshold Vth2. Therefore, the comparator 22 starts outputting the detection signal S1 to the controller 7 . Therefore, the control unit 7 detects the output of the detection signal S1 from (the comparison unit 22 of) the current detection unit 6, and determines the drive voltage Vdv for each of the n-type MOSFETs 4a and 5a of the reverse connection protection element 4 and the current control element 5. The output is stopped and this stopped state is continued. This stops the discharge from the battery 42 when trouble occurs.

Thus, according to the charging control circuit 1C, the output DC voltage V1 charges the battery 42 when the converter 41 as a bi-directional converter is normally operating (current output operation to the battery 42 side). When the voltage is higher than voltage V2, reverse connection protection element 4 and current control element 5 are turned on to supply charging current I1 from converter 41 to battery 42 (perform charging operation for battery 42), When a problem occurs on the converter 41 side, the output DC voltage V1 becomes lower than the charging voltage V2 of the battery 42, and a discharge current I2 is generated, the reverse connection protection element 4 and the current control element 5 are driven to the OFF state. As a result, discharging from the battery 42 to the converter 41 can be quickly prevented.

Further, according to the charge control circuit 1C, the reverse connection protection element 4 and the current control element 5 are turned on when the converter 41 as a bi-directional converter is in a normal operation (current input operation from the battery 42). When the battery 42 is driven, the discharge current I2 is supplied from the battery 42 to the converter 41 (the battery 42 is discharged), trouble occurs on the converter 41 side, and the discharge current I2 reaches the maximum discharge current value of the battery 42. When this occurs, reverse connection protection element 4 and current control element 5 can be driven to the OFF state to stop discharging from battery 42 to converter 41 .

Also in the charge control circuit 1C, both the current detection unit 6 and the control unit 7 provide a current between the second terminal 3a in the plus side power supply line La and the drain terminal of the n-type MOSFET 5a forming the current control element 5. It is configured so that it is not directly connected to the part via wiring. Therefore, even with the charging control circuit 1C, the reverse connection protection element 4 and the current control element 5 are driven to the OFF state, and in a state where the discharging from the battery 42 to the converter 41 is stopped, the charging control circuit 1C from the battery 42 Since generation of a minute current (dark current) flowing into (specifically, the current detection unit 6 and the control unit 7) can be avoided, useless discharge of the battery 42 can be completely prevented.

Also, since this charging control circuit 1C has the same configuration as the charging control circuit 1B (configuration including the temperature detecting section 31 and the correcting section), the same effects as those of the charging control circuit 1B can be obtained. can play.

In the charging control circuits 1A, 1B, and 1C, the first terminal 2a connected to one output terminal (positive terminal) of the converter 41 and the second terminal 3a connected to the anode of the battery 42 are connected. Although a configuration is employed in which the reverse connection protection element 4 and the current control element 5 are connected in series to the power supply line La on the positive side, the configuration is not limited to this configuration. For example, as in the charging control circuit 1D shown in FIG. It is also possible to employ a configuration in which it is arranged in the negative power supply line Lb that connects to the second terminal 3b.

This charging control circuit 1D will be described with reference to FIG. The charging control circuit 1D employs, as an example, a configuration based on the charging control circuit 1A shown in FIG. A configuration can also be adopted. Also, the same reference numerals are assigned to the same configurations as those of the charge control circuit 1A, and overlapping descriptions are omitted, and different configurations are mainly described.

The charging control circuit 1D includes a pair of first terminals 2a and 2b, a pair of second terminals 3a and 3b, a reverse connection protection element 4, a current control element 5, a current detection section 6, and a control section 7A. 2, a charging current I1 is output (supplied) to the battery 42 connected to the second terminal 3 based on the DC voltage V1 output from the converter 41 connected to the second terminal 3 to charge the battery 42.

The reverse connection protection element 4 is arranged on the power supply line Lb, and the current control element 5 is arranged on the power supply line La. In this example, the reverse connection protection element 4 is configured by a parallel circuit of an n-type MOSFET 4a and a diode 4b connected in parallel thereto, and the drain terminal of the n-type MOSFET 4a is connected to the second terminal through the power supply line Lb. 3b, and the source terminal is connected to the first terminal 1b via the power line Lb. Further, the current control element 5 is composed of a parallel circuit of an n-type MOSFET 5a and a diode 5b connected in parallel thereto. , the source terminal is connected to the first terminal 1a via the power line La.

The potential difference detection unit 21 of the current detection unit 6 is connected to one end (drain terminal of the n-type MOSFET 4a) and the other end (source terminal of the n-type MOSFET 4a) of the reverse connection protection element 4 via a pair of detection lines Ls1 and Ls2. there is In addition, the potential difference detection unit 21 amplifies the potential difference Vds between both ends of the reverse connection protection element 4 (between the drain and source terminals of the n-type MOSFET 4a) and outputs a current whose voltage value changes in proportion to the potential difference Vds. It outputs the detection signal Vi. This potential difference Vds becomes a positive (plus) voltage when the potential of one end (drain terminal) of the reverse connection protection element 4 is higher than the potential of the other end (source terminal) of the reverse connection protection element 4, and the potential of one end (drain terminal) of the reverse connection protection element 4 On the other hand, when the other end (source terminal) is at a low potential, it becomes a negative (negative) voltage. As a result, the potential difference detection unit 21 detects the magnitude of the discharge current I2 based on the potential difference Vds, and also detects the current detection signal Vi (the magnitude of the discharge current I2) whose voltage value changes in proportion to the detected magnitude. signal) is output.

The comparison unit 22 compares the current detection signal Vi with the current threshold value Vth to determine if the magnitude of the current detection signal Vi is equal to or greater than the current threshold value (that is, if the magnitude of the discharge current I2 is equal to or greater than the predetermined current value). value or more), a detection signal S1 indicating this comparison result is output to the control unit 7A.

The control unit 7A includes, for example, a processing circuit 51 composed of a CPU and memory, a first drive circuit 52 for driving the n-type MOSFET 4a, and a second drive circuit 53 for driving the n-type MOSFET 5a. configured with. In this example, as an example, the control unit 7A, when the content of the operation instruction Ss input from an input unit (not shown) provided inside or outside the charging control circuit 1D indicates a charging operation, performs a charging operation. The control circuit 1D is operated in the charging state.

In this charging state, the control unit 7A permits the current to flow in both directions when detecting the output of the detection signal S1 from the current detection unit 6 (that is, either the charging current I1 or the discharging current I2 Of the n-type MOSFETs 4a and 5a of the reverse connection protection element 4 and the current control element 5, which were driven to the ON state, at least the n-type MOSFET 5a of the current control element 5 (in this example, the reverse connection protection element The n-type MOSFETs 4a, 5a) of both 4 and current control element 5 are driven to the off state preventing the passage of discharge current I2.

In addition, in the control unit 7A, the first drive circuit 52 is connected to the source terminal of the n-type MOSFET 4a constituting the reverse connection protection element 4 via one drive line Ld1, and is connected to the gate terminal and one drive line. It is connected via Ld2. Further, the first drive circuit 52 is controlled by the processing circuit 51, and when the n-type MOSFET 4a constituting the reverse connection protection element 4 is shifted to the ON state (operation state in the saturation region), the gate threshold voltage value is When the drive voltage Vdv1 exceeding the voltage value is output between the drive lines Ld1 and Ld2 and the n-type MOSFET 4a is turned off, the output of the drive voltage Vdv1 is stopped (the voltage value of the drive voltage Vdv1 is set to be less than the gate threshold voltage value). to).

The second drive circuit 53 is connected to the source terminal of the n-type MOSFET 5a constituting the current control element 5 via one drive line Ld3, and is connected to the gate terminal via one drive line Ld4. It is Further, the second drive circuit 53 is controlled by the processing circuit 51 to set the gate threshold voltage value to When the drive voltage Vdv2 exceeding the voltage value is output between the drive lines Ld3 and Ld4 and the n-type MOSFET 5a is shifted to the OFF state, the output of the drive voltage Vdv2 is stopped (the voltage value of the drive voltage Vdv2 is set to be less than the gate threshold voltage value). to).

From the above, in the charging control circuit 1D, both the current detection unit 6 and the control unit 7A connect the second terminal 3a in the power supply line La on the positive side and the drain terminal of the n-type MOSFET 5a that constitutes the current control element 5. and are not directly connected via wiring to the part between them.

Next, operation of the charging control circuit 1D will be described with reference to FIG. It is assumed that the converter 41 is connected to the first terminal 2 and the battery 42 is connected to the second terminal 3 . It is also assumed that the DC voltage V1 output from the converter 41 during normal operation is set to a voltage higher than the charging voltage V2 of the battery 42 in the fully charged state.

In this state, when an operation instruction Ss indicating a charging operation is input, in the control unit 7A, the processing circuit 51 controls the first driving circuit 52 to generate a driving voltage exceeding the gate threshold voltage value. Vdv1 is output between the drive lines Ld1 and Ld2, and the second drive circuit 53 is controlled to output the drive voltage Vdv1 having a voltage value exceeding the gate threshold voltage value between the drive lines Ld3 and Ld4. As a result, the n-type MOSFETs 4a and 5a constituting the reverse connection protection element 4 and the current control element 5 are both turned on (a state allowing current to pass in both directions).

Therefore, when the converter 41 is operating normally, the output DC voltage V1 is higher than the charging voltage V2 of the battery 42. Therefore, the charging control circuit 1D controls the reverse connection protection element 4 in the ON state and the current control circuit 1D. A charging current I1 is supplied from the converter 41 to the battery 42 via the n-type MOSFETs 4a and 5a of the element 5 (the battery 42 is charged). In this case, the potential difference Vds detected by the potential difference detection unit 21 of the current detection unit 6 becomes a negative voltage, so that the current detection signal Vi also becomes a negative voltage (less than the low-side current threshold Vth1). Therefore, the comparator 22 stops outputting the detection signal S1 to the controller 7A. Therefore, in the control unit 7A, the processing circuit 51 controls the drive circuits 52 and 53 to continue the output of the drive voltages Vdv1 and Vdv2 to the n-type MOSFETs 4a and 5a of the reverse connection protection element 4 and the current control element 5. do. Thereby, the charging operation for the battery 42 is continued.

In this charging state, if some trouble occurs on the converter 41 side and the DC voltage V1 drops below the charging voltage V2 of the battery 42, the reverse connection protection element 4 and the current control element 5 in the on state A discharge current I2 flowing from the battery 42 to the converter 41 flows (is generated) in the n-type MOSFETs 4a and 5a. In this case, the potential difference Vds detected by the potential difference detection section 21 of the current detection section 6 becomes a positive voltage, so that the current detection signal Vi also becomes a positive voltage.

In this example, as described above, the current threshold value of the low voltage value (low side current threshold value Vth1) is defined so that the current detection unit 6 can detect the generation of the discharge current I2 from the state of the low current value. ing. Therefore, when the discharge current I2 with a low current value is generated, the positive voltage current detection signal Vi reaches the low-side current threshold Vth1. As a result, the comparator 22 outputs the detection signal S1 to the controller 7A. Further, in the control unit 7A, the processing circuit 51 detects the output of the detection signal S1 from the current detection unit 6 (comparison unit 22 thereof) and The drive circuits 52 and 53 are controlled to stop the output of the drive voltage Vdv to , and the control of the drive circuits 52 and 53 is continued. Therefore, each n-type of the reverse connection protection element 4 and the current control element 5 that have been driven in an ON state that allows bidirectional passage of current (that is, allows passage of both the charging current I1 and the discharging current I2) MOSFETs 4a and 5a are driven to an off state preventing the passage of current in both directions. This prevents discharge from battery 42 to converter 41 when trouble occurs.

As described above, according to the charge control circuit 1D, when the converter 41 is operating normally and the output DC voltage V1 is higher than the charging voltage V2 of the battery 42, the reverse connection protection element 4 and the current control The element 5 is driven to the ON state, the charging current I1 is supplied from the converter 41 to the battery 42 (the battery 42 is charged), trouble occurs on the converter 41 side, and the output DC voltage V1 becomes When the charging voltage V2 of the battery 42 becomes lower than the discharge current I2 and the discharge current I2 is generated, the reverse connection protection element 4 and the current control element 5 are driven to the OFF state to quickly prevent discharge from the battery 42 to the converter 41. can be done. In addition, in the charge control circuit 1D, as described above, both the current detection unit 6 and the control unit 7A connect the second terminal 3a in the power supply line La on the positive side and the drain terminal of the n-type MOSFET 5a constituting the current control element 5. and are not directly connected via wiring to the part between them. Therefore, according to this charge control circuit 1D, in a state in which the reverse connection protection element 4 and the current control element 5 are driven to the OFF state to prevent discharge from the battery 42 to the converter 41, the charge control circuit 1D from the battery 42 Since generation of a minute current (dark current) flowing into 1D (specifically, the current detection unit 6 and the control unit 7A) can be avoided, useless discharge of the battery 42 can be completely prevented (prevented).

Although the converter 41 has been described as an example of the power supply, the present invention is not limited to this, and the power supply may be a switching power supply or another battery.

1A, 1B, 1C, 1D charge control circuit
4 Reverse connection protection element
5 current control element
6 current detector
7, 7A control unit 41 converter 42 battery I1 charge current I2 discharge current La, Lb power supply line Ls1, Ls2 detection line S1 detection signal Vds potential difference Vth1 low-side current threshold

Claims (5)

A reverse connection protection element and a current control element connected in series to a plus side power supply line connecting a power supply device and a battery, and a discharge current from the battery to the power supply device via the power supply line. a current detection unit that detects the magnitude and outputs a detection signal based on the detection result; and a control unit for driving at least the current control element out of the reverse connection protection element and the current control element driven to the off state to block passage of the discharge current. hand,
the reverse connection protection element and the current control element are arranged in a state in which the current control element is located on the battery side with respect to the reverse connection protection element,
The current detection unit detects the magnitude of the discharge current based on a potential difference across the reverse connection protection element detected through a pair of detection lines connected to one end and the other end of the reverse connection protection element. Also, in a charging state in which a charging current is supplied from the power supply device to the battery via the power supply line, the detection result indicates that the magnitude of the discharging current is equal to or greater than a predetermined low-side current threshold. A charge control circuit that outputs the detection signal when the a current control element disposed on the positive side power line of the positive side power line and the negative side power line connecting the power supply device and the battery; and a reverse connection protection element disposed on the negative side power line. a current detection unit for detecting the magnitude of the discharge current from the battery to the power supply device via the power supply line and outputting a detection signal based on the detection result; When the output is detected, at least the current control element out of the reverse connection protection element and the current control element that has been driven to an ON state allowing bidirectional passage of current is prevented from passing the discharge current. A charging control circuit comprising a control unit that drives to an off state,
The current detection unit detects the magnitude of the discharge current based on a potential difference across the reverse connection protection element detected through a pair of detection lines connected to one end and the other end of the reverse connection protection element. Also, in a charging state in which a charging current is supplied from the power supply device to the battery via the power supply line, the detection result indicates that the magnitude of the discharging current is equal to or greater than a predetermined low-side current threshold. A charge control circuit that outputs the detection signal when the a temperature detection unit that detects the temperature of the reverse connection protection element and outputs a temperature detection signal indicating the temperature;
3. The charging control circuit according to claim 1, further comprising a correction section that reduces the low-side current threshold when the temperature indicated by the temperature detection signal is lower than a predetermined temperature. 4. The charging control circuit according to claim 3, wherein said correction unit increases said low-side current threshold when said temperature indicated by said temperature detection signal is higher than said predetermined temperature. The current detection unit is configured such that, in a discharge state in which the discharge current is supplied from the battery to the power supply device via the power supply line, the magnitude of the discharge current is predetermined to be higher than the low-side current threshold. 5. The charge control circuit according to any one of claims 1 to 4, wherein the detection signal is output when the detection result indicates that the current is equal to or higher than the high-side current threshold.

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