TW201421852A - Charger circuit and charging control method - Google Patents

Abstract

The present invention discloses a charger circuit and a charging control method, for charging a battery. When the battery voltage reaches a predetermined voltage, the electric quantity of the battery is measured to determine whether to charge the battery in a constant current mode wherein the battery is charged by a constant current, or in a constant voltage mode wherein the battery voltage is a target to be regulated to a target voltage.

Description

Charger circuit and charging control method

The invention relates to a charger circuit and a charging control method, in particular to a charger circuit and a charging control method for sensing battery power.

Please refer to FIG. 1, which shows a schematic diagram of a prior art charger circuit 1. Among them, the power supply 11 converts the input voltage of the input terminal into the output voltage of the output terminal, and the output terminal supplies the current to the battery circuit 14 via the current supply circuit 12.

The power supply circuit 11 and the current supply circuit 12 are controlled by the control circuit 16. When the voltage detecting circuit 15 detects that the voltage of the battery circuit 14 has not reached the preset voltage, the control circuit 16 controls the current supply circuit 12 to fix the current to the battery circuit 14. Charging, that is, the standard of the regulation control is mainly current, which is called constant current mode; and when the voltage detecting circuit 15 detects that the voltage of the battery circuit 14 reaches the preset voltage, the standard of the adjustment control is changed to voltage, current The charging current of the supply circuit 12 to the battery circuit 14 gradually decreases until the battery voltage reaches a preset voltage target, which is referred to as a constant voltage mode.

However, such a use of measuring the battery voltage, after switching to the constant voltage mode of the charger circuit 1 in the constant current mode, requires a relatively long charging time. For the reason, please refer to FIG. 4A and FIG. 4B. At time t1, the voltage detecting circuit 15 detects that the voltage of the battery circuit 14 reaches the preset voltage V1 and starts switching to the constant voltage mode. Therefore, the charging current starts to gradually decrease. However, due to the effect of the internal parasitic resistance of the battery, when the detection voltage reaches the preset voltage V1, the internal voltage of the battery does not actually reach the preset voltage V1, but has been switched to the constant voltage mode, during which the charging current is decreasing. This makes the charging process relatively long.

One prior art is to shorten the charging time, and thus to detect the parasitic resistance inside the battery, as shown in the charging control flow chart of the prior art of FIG. 5, in the prior art, first select the first stage constant current mode for the battery. Charging, when the battery voltage reaches the preset voltage V1, measure the internal parasitic resistance of the battery, that is, the internal resistance of the battery RBAT; then, according to the detected internal resistance RBAT of the battery, set the target of the battery voltage, from the preset voltage V1 is raised to a preset voltage V2, and V2=V1+IA*RBAT, wherein, after the battery voltage reaches the preset voltage V1, the charging current IBAT of the second constant current mode is selected; then, when the battery voltage reaches the preset When the voltage is V2, the target setting of the battery voltage is adjusted back to V1. This prior art uses a two-stage constant current mode to charge the battery, that is, to select the first-stage constant current mode before the battery voltage reaches the preset voltage V1, and to preset after the battery voltage reaches the preset voltage V1. Between the voltages V2, the second-stage constant current mode is selected, and finally the target setting of the battery voltage is adjusted back to V1 to maintain the battery voltage in the constant voltage mode.

A disadvantage of this prior art is that if the measured resistance error is too large, the wrong charging current IBAT is set in the second constant current mode, which causes damage and safety of the charger circuit, and in view of this, The present invention is directed to the deficiencies of the prior art described above, and provides a charger circuit and a charging control method, which can select a charging mode according to the power consumption of the rechargeable battery and actual needs, thereby saving charging time and avoiding damage and safety of the charger circuit. problem.

One of the objects of the present invention is to provide a charger circuit.

Another object of the present invention is to provide a charging control method.

For the purposes of the above, in one aspect, the present invention provides a The charger circuit includes: a power supply circuit for converting an input voltage into an output voltage at an output; a current supply circuit coupled between the output terminal and a battery circuit to the battery circuit Charging; a metering and voltage detecting circuit coupled to the battery circuit to generate a voltage detecting signal related to the battery voltage, and a power sensing signal related to the battery power; and a control circuit according to the voltage detecting The signal signal and the power sensing signal are used to generate a control signal to control the power supply circuit and the current supply circuit. The control method includes: when the battery voltage reaches a predetermined voltage, sensing the signal according to the power to determine a constant current The battery circuit is charged in a mode or in a constant voltage mode, and the current charged in the constant current mode is a first fixed current value in which the battery voltage is adjusted.

In a preferred embodiment, the metering and voltage detecting circuit comprises a Voltaic Gauge.

The invention also provides a charging control method, comprising: converting an input voltage into an output voltage at an output; charging a battery from the output; detecting the battery voltage, when the detected value reaches a preset At the time of voltage, measuring the amount of the battery to generate a power sensing signal to determine the current in the constant current mode or in the constant voltage mode, and the current charged in the constant current mode is the first fixed current value. In this constant voltage mode, the battery voltage is used as an adjustment target.

In a preferred embodiment, the method further includes charging the battery circuit with a second fixed current value when the battery voltage is less than the predetermined voltage, wherein the second fixed current value is equal to or not equal to the The first fixed current value.

In a preferred embodiment, when the battery voltage reaches the preset voltage, the control method includes: (1) when the power sensing signal is less than a first preset power, in the constant current mode pair The battery circuit is charged, wherein the charging current is the first solid Constant current value until the power sensing signal reaches a second preset power; and (2) when the power sensing signal is greater than the second preset power, charging the battery circuit in the constant voltage mode to adjust The battery voltage is at a target voltage; wherein the second predetermined power is greater than the first predetermined power.

In a preferred embodiment, in step (1), the adjustment target of the battery voltage is temporarily set to a temporary target value, and the temporary target value is higher than the preset voltage.

If the preset voltage V1, the temporary target value is V2, and the target voltage is V3, in a preferred embodiment, V1 V3 V2.

The purpose, technical content, features and effects achieved by the present invention will be more readily understood by the detailed description of the embodiments.

Referring to Figure 3, there is shown a schematic diagram of a charger circuit 2 in accordance with one embodiment of the present invention. The charger circuit 2 of this embodiment is used to charge the battery circuit 24, and includes a power supply circuit 21, a current supply circuit 22, a voltage detection circuit 15, a meter 25, and a control circuit 26. The control circuit 26 controls the power supply circuit 21 and the current supply circuit 22 to convert the input terminal voltage into an output terminal voltage and charge the battery circuit 23. The meter 25 is coupled to the battery circuit 23, and when the battery voltage reaches the preset voltage V1, measures the amount of power of the battery to generate a power sensing signal. The voltage detecting circuit 15 is for detecting the battery voltage. If the meter 25 can also provide the battery voltage information, the voltage detecting circuit 15 can be omitted, or the meter 25 can be regarded as including the voltage detecting circuit 15. The control circuit 26 generates a control signal and selects a mode according to the battery voltage information and the power sensing signal. The control signal is adjusted according to the following conditions: (1) When the power sensing signal is less than the preset power X%, the control signal controls the power supply circuit 21 and the current supply circuit 22 in a constant current mode until the power sensing signal The preset power amount Y% is reached; and (2) when the power sensing signal is greater than the preset power amount Y%, the control signal controls the power supply circuit 21 and the current supply circuit 22 in the constant voltage mode to adjust the battery voltage to the preset voltage V1. Wherein, the preset power amount Y% is greater than the preset power amount X%.

Wherein, X and Y are, for example but not limited to, between 50 and 90 and between 70 and 99, respectively, as long as Y>X. In addition, in the constant current mode, the charging current is substantially adjusted to a fixed current; and in the constant voltage mode, the battery voltage is substantially adjusted to a fixed voltage, such as but not limited to the preset voltage V1 (may also be a positive or negative V1) Difference value). Further, the power supply circuit 21 may be, for example, a synchronous or non-synchronous step-down, step-up, back-pressure, or step-up/down type power conversion circuit as shown in Figs. 2A-2J.

Please refer to FIGS. 4A-4C, which show schematic diagrams of prior art and charge current and battery voltage waveforms generated in accordance with embodiments of the present invention. According to an embodiment of the invention, when the detected battery voltage has not reached the preset voltage V1, it is charged in the constant current mode. When the detected battery voltage reaches the preset voltage V1 (the actual battery voltage has not reached the preset voltage V1), the battery power is measured. When the power sensing signal is less than the preset power X%, the constant current mode is still selected. Charge the battery with a fixed current until the power sensing signal reaches the preset power Y%. At this time, the battery voltage will rise slightly above the preset voltage V1. Because the circuit is set to the current as the main control target, the preset voltage V1 is also exceeded. No problem, but if it is safe to worry about the conflict between the current and voltage feedback control in the circuit, the battery voltage can be temporarily set to any preset voltage V2 higher than the preset voltage V1, not intended to be preset. Voltage V2 is the target of regulation, but allows the circuit to operate in constant current mode. When the power sensing signal is greater than the preset power Y%, the constant voltage mode is selected. At this time, the target value of the battery voltage can be set to the preset voltage V3, V1. V3 V2, wherein the preset voltage V3 can be equal to, for example, the preset voltage V1 (the 4C figure is taken as an example, but is not limited thereto), and may be other voltages not lower than the preset voltage V1, and the battery voltage will be adjusted. This target value.

Comparing Fig. 4A, the present invention and the prior art charging current waveform can be seen that the charging current according to the embodiment of the present invention is relatively late, but stops charging earlier (assuming charging current is lower than the critical value, representing charging) This is done, therefore, the present invention completes charging earlier than the prior art, that is, the charging time of the present invention is shorter. In addition, since the constant current mode only needs to set a fixed charging current in the charging mode of the present invention, the manufacturing cost of the circuit is low. In addition, the present invention avoids calculation errors of internal resistance and reduces the risk of circuit damage (and safety). All of the above are advantages of the present invention over the prior art.

It should be noted that the present invention is based on the battery power as a main parameter for controlling the charging mode, and the meter is, for example but not limited to, a Voltaic Gauge, which is a kind based on battery voltage or/and charging current. The power indicator, which is related to the amount of power stored in the battery, is well known to those of ordinary skill in the art and will not be described herein.

Figure 6 is a flow chart showing the charging control according to an embodiment of the present invention. As shown in the figure, the constant current mode is first selected to charge the battery, and when the battery voltage reaches the preset voltage V1, the battery is measured; subsequently, according to The detected battery power, when the power is less than X%, continue to maintain the constant current mode charging current, and if necessary, the battery voltage target can be set, from the preset voltage V1 to the preset voltage V2 Then, when the battery reaches Y%, the target voltage of the battery is lowered to V3. See Figures 4A and 6 for such a basis. The charging method of the invention adopts a one-stage constant current mode to charge the battery, that is, before the battery voltage reaches the preset voltage V1, until the battery power reaches Y%, maintaining the same stage of the constant current mode, and finally The target setting of the battery voltage is adjusted to V3, where V3>=V1, after the battery reaches Y%, the battery voltage is maintained to V3 in constant voltage mode. However, the above description is only one of the embodiments. Referring to FIG. 4A, the charging current in the two-stage mode of the present invention is detected before and after detecting that the battery voltage reaches the preset voltage V1, that is, before and after the time t1. The set values do not have to be the same or they can be different.

The present invention has been described with reference to the preferred embodiments thereof, and the present invention is not intended to limit the scope of the present invention. In the same spirit of the invention, various equivalent changes can be conceived by those skilled in the art. For example, in the circuits of the various embodiments shown, elements that do not affect the main meaning of the signal, such as other switches, etc., can be inserted; all of these can be derived in accordance with the teachings of the present invention, and thus the scope of the present invention should encompass the above. And all other equivalent changes. In addition, any embodiment of the present invention is not required to achieve all of the objects or advantages, and therefore, any one of the claims is not limited thereto.

1,2‧‧‧Charger circuit

11,21‧‧‧Power supply circuit

12,22‧‧‧ Current supply circuit

14,24‧‧‧Battery Circuit

15‧‧‧Voltage detection circuit

16,26‧‧‧Control circuit

25‧‧‧meter

Figure 1 shows a schematic diagram of a prior art charger circuit 1.

Figure 2A-2J shows a synchronous or non-synchronous buck, boost, back-pressure, or buck-boost power conversion circuit.

Figure 3 shows an embodiment of the invention.

4A-4C are schematic views showing the prior art and the charging current and battery voltage waveforms generated in accordance with an embodiment of the present invention.

Figure 5 shows a prior art charge control flow chart.

Figure 6 shows a flow chart of the charging control in accordance with the present invention.

2‧‧‧Charger circuit

15‧‧‧Voltage detection circuit

21‧‧‧Power supply

22‧‧‧ Current supply circuit

24‧‧‧Battery Circuit

25‧‧‧meter

26‧‧‧Control circuit

Claims (11)

A charger circuit includes: a power supply circuit for converting an input voltage into an output voltage at an output; a current supply circuit coupled between the output terminal and a battery circuit to the battery Circuit charging; a metering and voltage detecting circuit coupled to the battery circuit to generate a voltage detecting signal related to the battery voltage, and a power sensing signal related to the battery power; and a control circuit according to the voltage Detecting a signal and a power sensing signal to generate a control signal to control the power supply circuit and the current supply circuit, wherein the control method comprises: when the battery voltage reaches a predetermined voltage, sensing the signal according to the power to determine The battery circuit is charged in a flow mode or in a constant voltage mode, and the current charged in the constant current mode is a first fixed current value in which the battery voltage is adjusted. The charger circuit of claim 1, wherein the control method further comprises: when the battery voltage is less than the preset voltage, charging the battery circuit with a second fixed current value, wherein the second fixed current The value is equal to or not equal to the first fixed current value. The charger circuit of claim 1, wherein when the battery voltage reaches the preset voltage, the control method comprises: (1) when the power sensing signal is less than a first preset power, The constant current mode charges the battery circuit, wherein the charging current is the first fixed current value until the power sensing signal reaches a second preset power; and (2) when the power sensing signal is greater than the second When the power is preset, the constant The voltage mode charges the battery circuit to adjust the battery voltage to a target voltage; wherein the second predetermined power is greater than the first predetermined power. The charger circuit of claim 3, wherein the target voltage is greater than or equal to the preset voltage. The charger circuit of claim 1, wherein the metering and voltage detecting circuit comprises a Voltaic Gauge. A charging control method includes: converting an input voltage into an output voltage at an output; charging a battery from the output; detecting the battery voltage, and measuring when the detected value reaches a predetermined voltage The battery power is generated to generate a power sensing signal to determine the battery circuit in a constant current mode or a constant voltage mode, and the current charged in the constant current mode is a first fixed current value, in the constant voltage mode The battery voltage is used as the adjustment target. The charging control method of claim 6, further comprising: when the battery voltage is less than the preset voltage, charging the battery circuit with a second fixed current value, wherein the second fixed current value is equal to or not Equal to the first fixed current value. The charging control method of claim 6, wherein when the battery voltage reaches the preset voltage, the control method comprises: (1) when the power sensing signal is less than a first preset power, The constant current mode charges the battery circuit, wherein the charging current is the first fixed current value until the power sensing signal reaches a second preset power; and (2) when the power sensing signal is greater than the second When the power is preset, the battery circuit is charged in the constant voltage mode to adjust the battery voltage to a target a voltage; wherein the second preset power is greater than the first preset power. The charging control method of claim 8, wherein the target voltage is greater than or equal to the preset voltage. The charging control method according to claim 8, wherein in the step (1), the adjustment target of the battery voltage is temporarily set to a temporary target value, and the temporary target value is higher than the preset voltage. The charging control method according to claim 10, wherein the predetermined voltage V1, the temporary target value is V2, and the target voltage is V3, then V1 V3 V2.