JPH04193034A - Charging circuit - Google Patents

Abstract

PURPOSE:To make a reliable decision of battery loading by detecting the voltage at the time of turn OFF of a switching means thereby detecting the output voltage of a constant current supply and making judgment that a battery is not loaded if the battery voltage reaches a level lower, by a predetermined amount, than thus detected output voltage of the constant current supply during charging operation. CONSTITUTION:Battery voltage VB is outputted at a terminal 6 when a transistor SW 5 is turned ON and a battery pack 3 is loaded. The voltage does not exceed a level, equal to the output voltage of an AC adapter 1 minus the saturation voltage VSAT of the transistor 5, even if the battery voltage VB rises. When the battery pack 3 is not loaded, only a trickle current flows because of a voltage devision resistor 4 and thereby the voltage VCE of the transistor SW 5 drops below the saturation voltage VSAT and approaches to the output voltage of the AC adapter 1. When the battery voltage VB exceeds a level, equal to the output voltage of the AC adapter 1 minus the saturation voltage VSAT of the transistor SW5, a decision is made that the battery pack 3 is not loaded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a charging circuit for rapidly charging a battery.

[Prior Art] As an example, FIG. 7 shows a configuration block diagram of a device that can be charged with a constant current source AC adapter 1. An AC adapter 1 for supplying a constant current to the battery is detachable and connected to A and C adapter terminals 8. The main body includes a switch circuit (switch means) 5 consisting of a transistor SW5 that turns on and off the charging current to the battery, and a charging control circuit 2 consisting of a CPU that controls the transistor SW5.
It is composed of voltage dividing resistors 4 and the like that divide the voltage of the battery. 1 Sotery pack 3 with built-in battery B
is detachable and is connected to the terminal 6. When both the AC adapter 1 and the notebook computer 3 are attached, the main body is driven and the battery B is charged.

FIG. 8 shows the voltage characteristics and the operation will be explained.

When the AC adapter 1 is attached to the main body, voltage is supplied to the charging control circuit 2 and it starts operating. When both AC adapter 1 and battery pack 3 are installed, transistor SW5 as a quick charging switch is turned on, and a constant current of approximately IC (current that will fully charge battery B in 1 hour) is transferred from AC adapter 1 to battery. By charging the battery pack 3, the battery pack 3 is rapidly charged. During charging, the battery voltage is monitored by the A/D converter 2a built in the charge control circuit 2 through the voltage dividing resistor 4, and when the battery voltage drops by a predetermined voltage from the peak voltage, it is assumed that the battery is fully charged and the transistor SW5 is activated. Turn off and stop charging (-△V control). Alternatively, you can stop charging in the same way when a predetermined time has elapsed after starting charging (charging timer system 11).
1) Input the voltage detected by the voltage dividing resistor 9 for attachment detection of the AC adapter 1 to the charging control circuit 2. When the input voltage is at L level (Ov), it is not installed, and when it is at H level, it is installed. In order to start charging, it is necessary to determine whether the battery pack 3 is attached. When battery pack 3 is not installed, there is an AC connection between ends 6.
Since the voltage of the adapter l is output, the output of the voltage dividing resistor 4 is lower than the specified voltage (usually from the voltage of the AC adapter l) -
It is assumed that battery pack 3 is installed when the saturation voltage V of transistor SW5 is the value minus SAT.

Next, the operation will be explained using the flowchart shown in FIG. First, when the CPU of the charging control circuit 2 starts operating,
Clear the sampling timer t, the charging timer tCHG, and the maximum value VMAX of the battery voltage VB to 0. When sampling timer t or sampling time t SMP is reached, repeat the following operation. Then, check whether AC adapter 1 is attached. When AC adapter 1 is installed (input or H level)
, λ, and Terry voltage VB are A/D converted and taken in. When the captured value VB is smaller than the rated voltage VADP of the AC adapter 1, it is assumed that the battery pack 3 is attached. When the battery pack 3 is attached, it is checked whether the attached battery pack 3 is already fully charged by the full charge flag.

When the full charge flag is off and the battery is not fully charged, the transistor SW5 is turned on to perform rapid charging.

During quick charging, the charging timer tCHG counts up. Next, compare the captured battery voltage VB with the maximum value VMAX of the battery voltage VB, and if it is larger, V MA
Update X. If it is smaller, VMAX-VB is calculated, and if the value is larger than the value △V of the △V control, it is assumed that the battery is fully charged, and the transistor SW5 is turned off to perform trickle charging, and at the same time, the full charge flag is turned on.

When updating VMAX or VMAX-VB△■
If it is smaller, the charging timer tCHG is compared with the charging completion time [tSAF, and if it is larger, it is determined that the time is up, and charging is stopped and the full charge flag is turned on at the same time. Rapid charging continues when the time is not up. When the full charge flag is on and the hatchback 3 is already fully charged, the transistor SW5 continues to be off.

When AC adapter 1 is not installed (AC adapter 1 is manually operated or L is used), the full charge flag is turned off, and the charging timer tCHG and the maximum voltage value VMAX are cleared. When the hatchback 3 is not installed or removed (when the captured value VB is equal to the rated voltage V ADP of the AC adapter 1), the full charge flag is turned off, and the charging timer tCHG and the maximum battery voltage value VMAX are cleared.

By repeating the above steps, when both AC adapter 1 and battery pack 3 are installed, battery pack 3 can be charged rapidly (in a short time) until it is fully charged, and when it is fully charged, charging can be stopped. Can be stopped.

[Invention or problem to be solved]

The AC adapter 1 is available for various devices, and its rated output (output voltage, output current) differs depending on the device. The AC adapter 1 can be connected to any device as long as it has a jack. Therefore, there is a possibility that an AC adapter having a rating different from that of the main unit may be connected to the main unit. In particular, for personal computers, etc., it is necessary to have an AC adapter that can be used with all types of personal computers. For models with new functions or additions, there is a possibility that the AC adapter may be connected to a voltage or current that is insufficient for the previous model's rating. In the flowchart shown in FIG. 9, the battery voltage V
B and the rated voltage V AD set in advance in the charging control circuit 2
It is assumed that battery pack 3 is installed when P is smaller than VB or ■ADP.

Therefore, when the battery voltage VB exceeds the rated voltage VADP, it is determined that the battery bank 3 is not installed, and charging is stopped, so there is a problem in that the battery bank 3 cannot be charged.

Also, when an AC adapter with a lower voltage than the specified voltage or rated voltage V ADP is attached, battery pack 3 is always determined to be attached, and even though battery pack 3 is not attached, the charging current or output In order to be
There was a problem that a lot of power was wasted, and since charging was not controlled, the temperature of the charging circuit would rise, potentially causing damage to the circuit and fire.

The present invention has been provided in view of the above points, and even if the output voltage of the constant current source connected is
It is an object of the present invention to provide a charging circuit that can reliably determine whether or not a battery is attached even if the output voltage increases. A switch means is provided between the source and the battery, a voltage detection section is provided between the constant current source and the switch means, and the output voltage of the constant current source is detected by detecting the voltage when the switch means is turned off, The switch means is turned off, and when the battery voltage reaches a voltage lower than the output voltage of the detected constant current source by a predetermined value during charging, it is determined that the battery is not installed, and the control means is turned off.

Further, in claim 2, a bypass circuit for trickle charging is provided in parallel with the switch means, and when the switch means is off, the battery voltage reaches a voltage lower than the detected constant current source voltage by a second predetermined value during trickle charging. The device is equipped with a control means that determines that the battery is not installed and turns off the switch means.

Furthermore, in a third aspect of the present invention, when the switch means is turned off to shift from the first predetermined value to the second predetermined value, the control means is provided for inhibiting the battery installation determination for a predetermined period of time.

[For production]

Then, the output voltage of the constant current source is detected by detecting the voltage when the switch means is turned off, and the battery voltage is increased by a predetermined value from the detected output voltage of the constant current source while the switch means is turned off and charging is performed. By determining that the battery is not installed when the voltage reaches a low level, it is determined that the battery is not installed, regardless of the output voltage of the constant current source, or even if the voltage of the battery rises to the voltage of the constant current source. We ensure that decisions can be made reliably.

Claim 2 further provides that the switch means is turned off and the battery voltage is determined from the constant current source voltage detected during trickle charging.
By determining that the battery is not installed when the voltage reaches a predetermined value lower than , it is possible to reliably determine whether the battery is installed during trickle charging, regardless of the output voltage of the constant current source. There is.

Furthermore, claim 3 prohibits battery determination for a predetermined period of time, so that even if it is the output voltage of a constant current source or something like that, false detection will occur when transitioning from quick charging to trickle charging. This makes it possible to reliably determine whether or not to install a battery without having to do anything.

[Example 1] Hereinafter, an example of the present invention will be described with reference to the drawings. A block diagram is shown in FIG. In this embodiment, in the conventional circuit, the output voltage of the voltage dividing resistor 9 while the transistor SW5 is off is taken into the A/D converter 2b built in the charging control circuit 2, the voltage value is stored, and the battery back 3 is attached. The voltages V and DP are set as criteria for judgment.

When the transistor SW5 is on and the battery pack 3 is installed, the battery voltage VB is connected to the terminal 6.
AC is output even if the battery voltage increases
It does not become larger than the value obtained by subtracting the saturation voltage VSAT of the tiger 2 and nonuta SW5 from the output voltage of the adapter 1. When the hatchback 3 is not attached, only a small amount of current flows through the voltage dividing resistor 4, so that the VCE of the l-lanosystor SW5 becomes smaller than the saturation voltage VSAT, and therefore approaches the output voltage of the AC adapter l. Therefore, 1 from the battery voltage VB or the output voltage of AC adapter 1,
When the saturation voltage VSAT of the lannostar SW5 is lower than /S, it is determined that the hatchet bag 3 is not attached.

Next, the operation will be explained using flowchart 1 in FIG. First, when the charging control circuit 2 starts operating, it clears the sampling timer t, the charging timer tCHG, and the maximum value VMAX of the battery voltage.

Further, the transistor SW5 is turned off. vinegar.

When the bling timer t or the sampling time t SMP is reached, the following operation is repeated. The voltage VA of the AC adapter l is converted to A by the A/D converter 2b via the voltage dividing resistor 9.
/D conversion and import, output voltage VA of AC adapter l
Check whether it is 0■ or not.

When it is OV, it is assumed that AC adapter I is not installed, and the voltage storage flag of AC adapter 1 is turned off.
W5).

If it is not Ov, it is assumed that AC adapter 1 is installed, and the AC adapter voltage storage flag indicates that the AC adapter is already connected.
Check whether the output voltage of adapter 1 is stored.

When the AC adapter voltage storage flag is off and not stored, it is stored as the output voltage VAO and the AC adapter voltage storage flag is turned on. Memory is not updated when the AC adapter voltage storage flag is on.

Next, the battery voltage VB of the hatchery bag 3 is converted into A/D by the voltage dividing resistor 4 and the A/D converter 2a and taken in. When the captured battery voltage is VB or Ov, battery back 3 is not installed (transistor S
(when W5 or off).

When the taken-in battery voltage VB is smaller than the value (VAO-, VSAT) obtained by subtracting the saturation voltage VSAT of the L-run star SW5 from the output voltage VAO of the attached AC adapter 1, it is assumed that the hatchback 3 is attached. When the pantry pack 3 is attached, a full charge flag is used to check whether the attached battery bag 3 is already fully charged. When the full charge flag is off and the battery is not fully charged, transistor SW5 is turned on to perform rapid charging. Charging timer t CH during quick charging
Count up G.

Next, take the battery voltage VB and C.

Compare the maximum value V MAX of the battery voltage, and if it is larger, V
Update MAX. If it is smaller, calculate VMAX-VB, and if it is thicker than that value or -△VIIIialO value△■, it is assumed that the battery is fully charged and turns off l-Lansostar SW5.
At the same time, turn on the full charge flag. When VMAX is updated, or when VMAX-VB is smaller than △V, charging timer tCHG and charging completion time tSAF (tSA
(F is 1 hour for a current IC), and if it is thicker, it is considered time up and charging is stopped and the full charge flag is turned on at the same time. If the battery runs out of time, continue rapid charging. When the full charge flag is on and the battery pack 3 is already fully charged, the transistor SW5 is kept off.

If the AC adapter voltage VA is 0 and the AC adapter 1 is not installed, turn off the AC adapter voltage storage flag,
0 When hatchback 3 is not installed or removed, transistor SW5 is turned off, the full charge flag is turned off, charging timer tCHG and battery voltage maximum value V M
By repeating the steps above to clear AX, when both AC adapter 1 and battery pack 3 are installed, battery pack 3 will be charged rapidly (in a short period of time) until it is fully charged. You can stop charging or stopping at any time.

In this way, when the AC adapter 1 is attached, the output voltage is memorized and the battery attachment determination voltage is set, so no matter what the output voltage of the AC adapter 1 is, or the voltage of the battery pack 3. Even if the output voltage of the AC adapter 1 increases, it is possible to reliably determine whether the battery pack 3 is attached.

[Embodiment 2] In the previous embodiment, the charging current is stopped when the battery pack 3 is fully charged, or the charging current is normally stopped after the charging is completed, as shown in FIG. 3, to ensure the capacity of the battery pack 3. When transistor SW5 is turned off, diode D
Bypass circuit 7 consisting of R1 and resistor R1 performs trickle charging in which a low rate charging current flows. At this time, if the battery voltage VB is taken in when the transistor SW5 is turned off, the voltage drop due to the bypass circuit 7 will be large, so even if the battery pack 3 is removed, the VAO-V
It does not exceed SAT and can only detect the attachment of battery pack 3.

Therefore, in the first embodiment, when the transistor SW5 is turned off, the battery attachment is determined based on the second hafty attachment determination value.

When the transistor SW5 is off and the battery pack 3 is attached to the terminal 6, /< battery voltage V
Even if B is output or the battery voltage VB increases, A
It does not become larger than the value obtained by subtracting the voltage drop VDROP of the bypass circuit 7 (resistance drop IXR + saturation voltage vF of the diode, where 2 is the trickle charging current) from the output voltage of the C adapter l. When the battery pack 3 is not attached, a small amount of current does not flow through the voltage dividing resistor 4, so the voltage drop in the bypass circuit 7 is V D
ROP (and approaches the output voltage of AC adapter 1. Therefore, during trickle charging, the battery voltage VB
When the output voltage of the AC adapter 1 exceeds a value lower by VDROP, it is determined that the battery pack 3 is not installed.

Next, the operation will be explained with reference to the flowchart shown in FIG.

First, when the charging control circuit 2 starts operating, it clears the sampling timer t, the charging timer tCHG, and the maximum value VMAX of the battery voltage.

Further, the transistor SW5 is turned off. When the sampling timer t reaches the sampling time t SMP, the following operation is repeated. AC adapter l voltage VA
is A/D converted by the A/D converter 2b via the voltage dividing resistor 9 and taken in, and the output voltage VA or Ov of the AC adapter l is obtained.
Find out whether

When it is 0■, it is assumed that AC adapter l is not installed, the voltage storage flag of AC adapter l is turned off, and transistor SW is turned off.
Turn off 5.

If it is not OV, it is assumed that AC adapter 1 is installed, and the AC adapter voltage storage flag indicates that the AC adapter is already connected.
Check to see if the output voltage of adapter l is memorized.

When the AC adapter voltage storage flag is off and has not been stored yet, the output voltage is stored as VAO and the AC adapter voltage storage flag is turned on. Memory is not updated when the AC adapter voltage storage flag is on.

Next, the battery voltage VB of the battery pack 3 is A/D converted by the voltage dividing resistor 4 and the A/D converter 2a and taken in. Next, check the state of transistor SW5. During trickle charging with transistor SW5, the captured value VB is the output voltage VAO of the attached AC adapter 1 minus the voltage drop V DROP caused by the bypass circuit 7.
Check whether the value is smaller than this value (VAO-VDROP), and if it is smaller, it is assumed that the battery pack 3 is attached.

During rapid charging with transistor SW5 on, the saturation voltage V S of transistor SW5 is determined by the captured battery voltage VB or the output voltage VAO of the attached AC adapter l.
Check whether it is smaller than the value minus AT (VA (] - VSAT). If it is smaller, it is assumed that battery pack 3 is installed. If hatchback pack 3 is installed (this is determined by the full charge flag) Check whether the installed /S5.T1(-P,T3) is already fully charged.If the full charge flag is off and the battery is not fully charged, turn on transistor SW5 and perform quick charging.During quick charging counts up the charging timer tCHG.

Next, compare the captured battery voltage VB and the maximum value VMAX of the battery voltage (VMAX), and the thickest one is VMAX.
Update. If it is smaller, VMAX-VB is calculated, and if the value is greater than -△■ control value △■, it is assumed that the battery is fully charged, and the transistor SW5 is turned off to perform trickle charging.At the same time, the full charge flag is turned on. When V MAX is updated, or when Vl is smaller than 1AX-VB or △V, charging timer tCHG and charging completion time tSAP
(tSAF is 1 hour in the case of a current IC), and if it is larger, it is determined that the time has expired, the transistor SW5 is turned off, trickle charging is performed, and the full charge flag is turned on at the same time.

When the time is not up, rapid charging continues. When the full charge flag is on and battery pack 3 is already fully charged, l-recycle charging continues.

When the AC adapter voltage is VA or Ov and AC adapter 1 is not installed, turn off the AC adapter voltage storage flag.
Transistor SW5 is turned off. When battery bag 3 is not attached or removed, the full charge flag is turned off, and the charging timer tCHG and battery voltage maximum value V M
By repeating the steps above to clear AX, you can rapidly (in a short time) charge the battery pack 3 until it is fully charged, and when it is fully charged, you can shift to trickle charging. Also, the battery pack 3
It is possible to determine whether to install the

In this manner, in the second embodiment, regardless of the output voltage of the AC adapter 1, it is possible to reliably determine whether to attach the battery pack 3 during trickle charging.

[Third Embodiment] In the second embodiment, when charging of the hatchery bag 3 is completed and the transistor SW5 is turned off, the bypass circuit 7 performs trickle charging in which a low rate charging current flows. At this time, either the second judgment value is used to detect the pantry bag 3 oven, or the second judgment value is incorrect because the battery voltage gradually drops after turning off the transistor SW5, as shown in Figure 5. There is a possibility of detection.

Therefore, in the third embodiment, when the battery attachment is determined based on the second battery attachment determination value when the transistor SW5 is turned off, the determination is prohibited for a predetermined period of time after the transistor SW5 is turned off. This is how it was done.

Next, the operation will be explained with reference to the flowchart shown in FIG. In this embodiment, in Embodiment 2)
After checking the state of step 5 and turning off transistor SW5, during the judgment inhibition time tINHO, VB < VAO-VD.
This prohibits the judgment of ROP.

When the charging timer is completed due to quick charging or time-up detection or time-up, transistor SW5 is turned off, and judgment prohibition timer t INH is turned on when switching to l/recycle charging.
Clear to. When transistor SW5 is off and during 1~recycle charging, prohibition timer tlNH or judgment prohibition time t
Check whether it is larger than INHO. When it is small, count up t[NH. When it's big,
The voltage drop caused by the bypass circuit 7 is V DRO from the captured value VB or the output voltage VAO of the attached AC adapter 1.
Check whether it is smaller than the value obtained by subtracting P (VAO - VDROP). If it is smaller, it is assumed that battery pack 3 is installed. When it is large, it is assumed that 3 hatchery bags have been removed and the charging flag is turned off.

In this way, in this embodiment, no matter what the output voltage of the AC adapter l is, even when transitioning from quick charging to trickle charging, the battery pack 3 can be operated without erroneous detection.
It is possible to reliably determine whether to install the

〔Effect of the invention〕

As described above, the present invention provides a switch means between the constant current source and the battery, a voltage detection section between the constant current source and the switch means, and detects and determines the voltage when the switch means is turned off. Detects the output voltage of the current source, turns off the switch means, and when the battery voltage reaches a predetermined value lower than the output voltage of the detected constant current source during charging, determines that the battery is not installed and turns off the switch means. Since the control means is provided, the output voltage of the constant current source is detected by detecting the voltage when the switch means is turned off, and the output voltage of the constant current source is detected when the switch means is turned off and the battery voltage is detected during charging. It is determined that the battery is not installed when the voltage reaches a predetermined value 1 volt lower than the output voltage, and the output voltage of the constant current source or whatever it is, or the voltage of the battery or the voltage of the constant current source. Even if the battery rises, it is possible to reliably determine whether or not to install the battery.

Further, in claim 2, a bypass circuit for trickle charging is provided in parallel with the switch means, and when the switch means is off and the battery voltage is being trickle charged, the voltage is lower than the detected constant current source voltage by a second predetermined value. Since the device is equipped with a control means that determines that the battery is not installed and turns off the switch means when the voltage reaches the threshold, the switch means is turned off and the constant current source voltage detected during trickle charging is lower than the constant current source voltage by a second predetermined value. When the voltage reaches that voltage, it is determined that the battery is not installed.Whether it is the output voltage of a constant current source or whatever, it is possible to reliably determine whether the battery is installed during trickle charging.

Furthermore, in a third aspect of the present invention, when the switch means is turned off and the first predetermined value is shifted from the first predetermined value to the second predetermined value, the control means is provided for inhibiting the battery installation determination for a predetermined time. By prohibiting battery determination for a predetermined period of time, the output voltage of the constant current source, or whatever it is, can be used to ensure that the battery is installed without false detection when transitioning from fast charging to trickle charging. It is something that can be determined with certainty.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of an embodiment of the present invention, Fig. 2 is a flowchart of the same as above, Fig. 3 is a block diagram of Embodiment 2 of the same as above, Fig. 4 is a flowchart of the same as above, and Fig. 5 is a flowchart of the same as above. An explanatory diagram of the operation of Embodiment 3, FIG. 6 is the same flowchart as above, FIG. 7 is a block diagram of the conventional example, FIG. 8 is a battery voltage characteristic diagram as above, FIG. 9 is the same flowchart as above, and FIG.
The figure is an explanatory diagram same as the above. 1 is an AC adapter, 2 is a charging control circuit, 3 is a battery pack, 4 is a voltage dividing resistor, 7 is a bypass circuit, 9 is a voltage dividing resistor, and B is a battery. Agent Patent Attorney Ishi 1) Chief 7 Figure 2 Figure 4 Figure 8 Do--------11--A-Machi Koro'-Tetsu tttgin Award Figure 9

Claims (3)

[Claims] (1) In a charger that can be equipped with a constant current source for charging a battery, a switch means is provided between the constant current source and the battery, a voltage detection section is provided between the constant current source and the switch means, and a switch is provided between the constant current source and the battery. The output voltage of the constant current source is detected by detecting the voltage when the switching means is turned off, and when the battery voltage reaches a voltage lower by a predetermined value than the detected output voltage of the constant current source during charging with the switching means turned off. A charging circuit characterized by being provided with a control means for turning off a switch means when determining that a battery is not installed. (2) A bypass circuit for trickle charging is provided in parallel with the switch means, and when the switch means is off and the battery voltage reaches a voltage lower than the detected constant current source voltage by a second predetermined value during trickle charging, the battery is not installed. 2. The charging circuit according to claim 1, further comprising control means for determining that the switch means is turned off. (3) A control device according to claim 2, further comprising a control device that prohibits battery installation determination for a predetermined period of time when the switch device is turned off to shift from the first predetermined value to the second predetermined value. charging circuit.