Method for detecting disconnection of battery and online and offline uninterruptible power supply system

Abstract

The invention discloses a method for detecting whether a battery is disconnected or not and an online uninterruptible power system and an offline uninterruptible power system adopting the method. The method comprises the following steps: judging whether a charging circuit for charging a battery is in a constant voltage charging mode or not; and if yes, executing a battery disconnection detection program. The battery disconnection detection program comprises the steps that first operation and second operation are alternately executed on a pulse width modulation signal, the duty cycle of the pulse width modulation signal is used for controlling the output voltage of the charging circuit, the first operation is that the duty cycle of the pulse width modulation signal is increased by a first default value and lasts for a first default time, and the second operation is that the duty cycle of the pulse width modulation signal lasts for a second default time; the second operation is to recover the original duty cycle of the pulse width modulation signal and lasts for a second default time; and judging whether the voltage of the output end of the charging circuit rises and reaches a second default value or not.

Description

Technical Field

[0001] The present invention relates to the technical field of battery detection, and in particular to a method for detecting whether a battery is disconnected, and an online uninterruptible power system and an offline uninterruptible power system using the method. Background Art

[0002] Generally speaking, an uninterruptible power system (UPS) will detect whether the battery is disconnected at any time during the process of charging a battery (such as a lead-acid battery). However, when the battery is fully charged or nearly fully charged, the UPS cannot detect whether the battery is disconnected. In order to ensure that the UPS can maintain normal operation, the above problems need to be solved urgently. Summary of the invention

[0003] One of the objectives of the present invention is to provide a method for detecting whether a battery is disconnected, which can solve the above-mentioned problem.

[0004] Another object of the present invention is to provide an online uninterruptible power supply system using the above method.

[0005] Another object of the present invention is to provide an offline uninterruptible power supply system using the above method.

[0006] To achieve the above-mentioned purpose, the present invention provides a method for detecting whether a battery is disconnected, which includes the following steps: determining whether a charging circuit for charging a battery is in a constant voltage charging mode; and when the determination is yes, executing a battery disconnection detection procedure. The battery disconnection detection procedure includes the following steps: alternately performing a first operation and a second operation on a pulse width modulation signal, wherein the duty cycle of the pulse width modulation signal is used to control the output voltage of the charging circuit, the first operation is to increase the duty cycle of the pulse width modulation signal by a first default value and last for a first default time, and the second operation is to restore the original duty cycle of the pulse width modulation signal and last for a second default time; and determining whether the voltage at the output end of the charging circuit rises and reaches a second default value.

[0007] To achieve the above-mentioned another object, the present invention provides an online uninterruptible power supply system, which includes a charging circuit, a sensing circuit and a control unit, wherein the control unit further includes a digital control circuit and a driving circuit. The charging circuit is used to perform a DC-DC conversion operation and to charge a battery. The sensing circuit is used to sense the output of the charging circuit and generate a sensing result accordingly. The digital control circuit is used to generate a pulse width modulation signal according to the sensing result, and the duty cycle of the pulse width modulation signal is used to control the output voltage of the charging circuit. The driving circuit is used to generate a driving signal according to the pulse width modulation signal to drive the charging circuit. When the digital control circuit determines that the charging circuit is in a constant voltage charging mode according to the sensing result, the digital control circuit executes a battery disconnection detection procedure. The battery disconnection detection procedure includes the following steps: alternately performing a first operation and a second operation on the pulse width modulation signal, wherein the first operation is to increase the duty cycle of the pulse width modulation signal by a first default value and last for a first default time, and the second operation is to restore the original duty cycle of the pulse width modulation signal and last for a second default time; and determining whether the voltage at the output end of the charging circuit rises and reaches a second default value.

[0008] To achieve another object mentioned above, the present invention provides an offline uninterruptible power system, which includes a charging circuit, a sensing circuit and a control unit, wherein the control unit further includes a digital control circuit and a driving circuit. The charging circuit is used to perform an AC-DC conversion operation, and the output of the charging circuit is used to charge the battery and is used as a system power supply. The sensing circuit is used to sense the output of the charging circuit and generate a sensing result accordingly. The digital control circuit is used to generate a pulse width modulation signal according to the sensing result, and the duty cycle of the pulse width modulation signal is used to control the output voltage of the charging circuit, wherein the digital control circuit also has the function of stabilizing the output voltage of the charging circuit. The driving circuit is used to generate a driving signal according to the pulse width modulation signal to drive the charging circuit. When the digital control circuit determines that the charging circuit is in a constant voltage charging mode according to the sensing result, the digital control circuit executes a battery disconnection detection procedure. The battery disconnection detection procedure includes the following steps: alternately performing a first operation and a second operation on a pulse width modulation signal, wherein the first operation is to increase the duty cycle of the pulse width modulation signal by a first default value and last for the first default time, and to stop the function of stabilizing the output voltage of the charging circuit during the first default time, and the second operation is to restore the original duty cycle of the pulse width modulation signal and last for the second default time; judging whether the voltage at the output end of the charging circuit rises and reaches a second default value; when the voltage at the output end of the charging circuit reaches the second default value, stopping the first operation and the second operation, and increasing the duty cycle of the pulse width modulation signal so that the target voltage of the output voltage of the charging circuit rises to a third default value and is maintained for a third default time, wherein the third default value is greater than the second default value; and judging whether the voltage at the output end of the charging circuit still reaches the second default value within the third default time.

[0009] In order to make the above-mentioned objectives, technical features and benefits after actual implementation more obvious and understandable, a more detailed description will be given below with the help of preferred implementation examples and corresponding related drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0011] Figure 1 An online uninterruptible power supply system according to an embodiment of the present invention is illustrated.

[0012] Figure 2 One implementation of the charging circuit 114 is shown.

[0013] Figure 3 FIG. 4 is a flow chart of a method for detecting whether a battery is disconnected according to an embodiment of the present invention.

[0014] Figure 4 Used to illustrate the first operation and the second operation.

[0015] Figure 5 It is used to illustrate the change of the voltage V2 at the output end of the charging circuit 114.

[0016] Figure 6 An offline uninterruptible power supply system according to an embodiment of the present invention is illustrated.

[0017] Figure 7 One implementation of the charging circuit 614 is shown.

[0018] Figure 8 FIG. 4 is a flow chart of a method for detecting whether a battery is disconnected according to an embodiment of the present invention.

[0019] Fig. 9 It is used to illustrate the change of the voltage V4 at the output end of the charging circuit 614. DETAILED DESCRIPTION

[0020] In order to more clearly understand the features, contents and advantages of the present invention and the effects that can be achieved, the present invention is hereby described in detail in the form of embodiments in conjunction with the accompanying drawings. The drawings used therein are only for illustration and auxiliary description purposes and may not be the actual proportions and precise configurations after the implementation of the present invention. Therefore, the proportions and configuration relationships of the attached drawings should not be interpreted to limit the scope of rights of the present invention in actual implementation.

[0021] The advantages, features and technical methods of the present invention will be described in more detail with reference to exemplary embodiments and the accompanying drawings so that they are easier to understand, and the present invention may be implemented in different forms, so it should not be understood to be limited to the embodiments described herein. On the contrary, for those with ordinary knowledge in the relevant technical field, the provided embodiments will make this disclosure more thorough and comprehensive and completely convey the scope of the present invention, and the present invention will only be defined by the attached claims.

[0022] Figure 1 An on-line uninterruptible power system (on-line UPS) according to an embodiment of the present invention is shown. Figure 1As shown, the online uninterruptible power supply system 100 includes a filter unit 102, a switch unit 104, a power factor correction circuit (PFC circuit) 106, a DC-AC conversion circuit 108, a switch unit 110, a filter unit 112, a charging circuit 114, a battery 116, a sensing circuit 118, a control unit 120 and a bypass path 130, wherein the control unit 120 further includes a digital control circuit 122 and a driving circuit 124. The input end of the filter unit 102 is used as the input end of the online uninterruptible power supply system 100 and is electrically coupled to the AC mains, and the output end of the filter unit 112 is used as the output end of the online uninterruptible power supply system 100. The electrical coupling relationship of the above-mentioned components is as shown in FIG. Figure 1 In addition, although in this example, the battery 116 is disposed inside the online uninterruptible power supply system 100, this is not intended to limit the present invention, and a person skilled in the art should know that the battery 116 can also be disposed outside the online uninterruptible power supply system 100.

[0023] The control unit 120 uses the control signals C1, C2, C3 and C4 to respectively control the operations of the switch unit 104, the power factor correction circuit 106, the DC-AC conversion circuit 108 and the switch unit 110. For example, the control unit 120 uses the control signal C1 to control the operation of the switch unit 104 to electrically couple the output end of the filter unit 102 to the input end of the power factor correction circuit 106, or to electrically couple the output end of the filter unit 102 to the bypass path 130, or to electrically couple the battery 116 to the input end of the power factor correction circuit 106. For another example, the control unit 120 uses the control signal C4 to control the operation of the switch unit 110 to electrically couple the input end of the filter unit 112 to the output end of the DC-AC conversion circuit 108, or to electrically couple the input end of the filter unit 112 to the bypass path 130.

[0024] In this example, the charging circuit 114 is used to perform a DC-DC conversion operation and to charge the battery 116. The sensing circuit 118 is used to sense the output of the charging circuit 114 (e.g., sensing voltage, current), and generate a sensing result. The digital control circuit 122 is used to generate a pulse-width modulation signal (PWM signal) according to the sensing result, and the duty cycle of the pulse-width modulation signal is used to control the output voltage of the charging circuit 114. The driving circuit 124 is used to generate a driving signal DS according to the pulse-width modulation signal to drive the charging circuit 114.

[0025] Figure 2FIG. 1 is a diagram showing one implementation of the charging circuit 114. Figure 2 As shown, the charging circuit 114 is a step-down DC-DC converter circuit (Buck converter), which includes a switch 202, an inductor 204, a diode 206 and a capacitor 208. In addition, in this example, the switch 202 is implemented by an N-type metal-oxide-semiconductor field-effect transistor (N-type MOSFET). The gate of the N-type metal-oxide-semiconductor field-effect transistor is used as the control terminal of the switch 202 and is used to receive the driving signal DS output by the driving circuit 124. In addition, Figure 2 In FIG. 1 , V1 represents the voltage at the input end of the charging circuit 114, and V2 represents the voltage at the output end of the charging circuit 114. The electrical coupling relationship of the above components is as follows: Figure 2 It is worth mentioning that in other embodiments, the charging circuit 114 can also be implemented by a boost type DC-DC converter circuit (Boost converter).

[0026] Figure 3 This is a flow chart of a method for detecting whether a battery is disconnected according to an embodiment of the present invention. Figure 1 and Figure 3 First, the digital control circuit 122 determines whether the charging circuit 114 is in the constant voltage charging mode (as shown in step S310) based on the sensing result output by the sensing circuit 118. When the charging circuit 114 is in the constant voltage charging mode, it means that the battery 116 is fully charged or nearly fully charged. In this example, the digital control circuit 122 can obtain the information of the voltage V2 at the output end of the charging circuit 114 from the sensing result, and determine whether the charging circuit 114 is in the constant voltage charging mode based on it. When the judgment result is no, the digital control circuit 122 returns to step S310. When the judgment result is yes, the digital control circuit 122 executes the battery disconnection detection procedure (as shown in step S320).

[0027] The battery disconnection detection procedure includes the following steps: First, the digital control circuit 122 performs the first operation and the second operation alternately on the pulse width modulation signal (as shown in step S322). Figure 4 This is used to explain the first and second operations mentioned above. Figure 4, the first operation is to increase the duty cycle of the pulse width modulation signal by a first default value, and continue for a first default time. In this example, the first default value is 6%. Assuming that the original duty cycle of the pulse width modulation signal is 50%, the adjusted duty cycle is 56%. In addition, the second operation is to restore the original duty cycle of the pulse width modulation signal, and continue for a second default time. In this example, the duty cycle of the pulse width modulation signal is adjusted back from 56% to 50%. In this example, the first default time is 10 milliseconds, and the second default time is 30 milliseconds, but this is only used as an example and is not used to limit the present invention. In addition, the preferred numerical range of the first default value is 0.6%-1%, but this is also not used to limit the present invention. It is worth mentioning that, if Figure 4 As shown, the first operation and the second operation are adjacent to each other in time.

[0028] Please refer to Figure 1 and Figure 3 . Since the duty cycle of the PWM signal is used to control the output voltage of the charging circuit 114, the charging circuit 114 can output some additional energy by alternately performing the first operation and the second operation on the PWM signal. When the first default value, the first default time, and the second default time are properly designed, if the battery 116 is not disconnected, the additional energy output by the charging circuit 114 will be absorbed by the battery 116, so the voltage V2 at the output end of the charging circuit 114 will not rise. On the contrary, if the battery 116 is disconnected, the additional energy output by the charging circuit 114 cannot be absorbed by the battery 116, so the voltage V2 at the output end of the charging circuit 114 will rise.

[0029] As described above, after executing step S322, the digital control circuit 122 will determine whether the voltage at the output end of the charging circuit 114 rises and reaches the second default value (as shown in step S324) according to the sensing result output by the sensing circuit 118. When the voltage V2 at the output end of the charging circuit 114 reaches the second default value, the digital control circuit 122 determines that the battery 116 is disconnected (as shown in step S326). On the contrary, when the voltage V2 at the output end of the charging circuit 114 does not reach the second default value, the digital control circuit 122 determines that the battery 116 is not disconnected (as shown in step S328), and then returns to step S322.

[0030] Figure 5 That is, it is used to illustrate the change of the voltage V2 at the output end of the charging circuit 114. Figure 5As shown, when the extra energy output by the charging circuit 114 cannot be absorbed by the battery 116, the voltage V2 at the output end of the charging circuit 114 will rise (as shown by the mark 502), so it can be determined that the battery 116 is disconnected. Once it is determined that the battery 116 is disconnected, the charging circuit 114 can be turned off to avoid wasting energy. Therefore, the voltage V2 at the output end of the charging circuit 114 will begin to decrease (as shown by the mark 504).

[0031] Please refer to Figure 1 and Figure 3 In order to further determine whether the battery 116 is fully charged or nearly fully charged, in step S310, the digital control circuit 122 can determine whether the charging circuit 114 is in the constant voltage charging mode, and can further determine whether the charging current output by the charging circuit 114 is less than a default current value (for example, 0.3 amperes, but this is not intended to limit the present invention) based on the sensing result output by the sensing circuit 118. When both are determined to be yes, the digital control circuit 122 executes the battery disconnection detection procedure.

[0032] Please refer to Figure 4 ,Depend on Figure 4 It can also be seen that the first operation and the second operation can be performed even if the original duty cycle of the PWM signal is 0. In other words, even if the original duty cycle of the PWM signal is 0, the method of the present invention can still be performed to detect whether the battery 116 is disconnected.

[0033] Figure 6 An off-line uninterruptible power system (off-line UPS) according to an embodiment of the present invention is shown. Figure 6 As shown, the offline uninterruptible power supply system 600 includes a filter unit 102, a DC-AC conversion circuit 108, a switch unit 110, a filter unit 112, a charging circuit 614, a battery 116, a sensing circuit 118, a control unit 620 and a bypass path 130, wherein the control unit 620 further includes a digital control circuit 622 and a drive circuit 624. The input end of the filter unit 102 is used as the input end of the offline uninterruptible power supply system 600 and is electrically coupled to the mains, and the output end of the filter unit 112 is used as the output end of the offline uninterruptible power supply system 600. The electrical coupling relationship of the above-mentioned components is as follows. Figure 6 In addition, although in this example, the battery 116 is disposed inside the offline uninterruptible power supply system 600, this is not intended to limit the present invention, and a person skilled in the art should know that the battery 116 can also be disposed outside the offline uninterruptible power supply system 600.

[0034] The control unit 620 uses the control signals C3 and C4 to respectively control the operation of the DC-AC conversion circuit 108 and the switch unit 110. For example, the control unit 120 uses the control signal C4 to control the operation of the switch unit 110 to electrically couple the input end of the filter unit 112 to the output end of the DC-AC conversion circuit 108, or to electrically couple the input end of the filter unit 112 to the bypass path 130.

[0035] In this example, the charging circuit 614 is used to perform an AC-DC conversion operation, and the output of the charging circuit 614 is used to charge the battery 116. In addition, the output of the charging circuit 614 is also used as a system power supply. In other words, in addition to the battery 116, the output end of the charging circuit 614 is also electrically coupled to at least one load, and these loads rely on the system power supply to operate normally. The sensing circuit 118 is used to sense the output of the charging circuit 614 (for example, sensing voltage, current), and generate a sensing result accordingly. The digital control circuit 622 is used to generate a pulse width modulation signal according to the sensing result, and the duty cycle size of this pulse width modulation signal is used to control the output voltage size of the charging circuit 614. In addition, in this example, the digital control circuit 622 also has the function of stabilizing the output voltage size of the charging circuit 614. This function can stabilize the output voltage of the charging circuit 614 at the target voltage size. The driving circuit 624 is used to generate a driving signal DS according to the pulse width modulation signal to drive the charging circuit 614.

[0036] Figure 7 One implementation of the charging circuit 614 is shown. Figure 7 As shown, the charging circuit 614 is composed of a full bridge rectifier 710 and a buck type DC-DC converter circuit 720, wherein the buck type DC-DC converter circuit 720 further includes a switch 722, an inductor 724, a diode 726 and a capacitor 228. In addition, in this example, the switch 722 is implemented by an N-type metal oxide semiconductor field effect transistor. The gate of the N-type metal oxide semiconductor field effect transistor is used as the control terminal of the switch 722 and is used to receive the driving signal DS output by the driving circuit 624. In addition, in Figure 7 In FIG. 6 , V3 represents the voltage at the input terminal of the charging circuit 614, and V4 represents the voltage at the output terminal of the charging circuit 614. The electrical coupling relationship of the above components is as follows: Figure 7 It is worth mentioning that in other embodiments, the charging circuit 614 can also be implemented by a combination of a full-bridge rectifier and a boost type DC-DC conversion circuit.

[0037] Figure 8This is a flow chart of a method for detecting whether a battery is disconnected according to an embodiment of the present invention. Figure 6 and Figure 8 First, the digital control circuit 622 determines whether the charging circuit 614 is in the constant voltage charging mode (as shown in step S810) based on the sensing result output by the sensing circuit 118. When the charging circuit 614 is in the constant voltage charging mode, it means that the battery 116 is fully charged or nearly fully charged. In this example, the digital control circuit 622 can obtain the information of the voltage V4 at the output end of the charging circuit 614 from the sensing result, and determine whether the charging circuit 614 is in the constant voltage charging mode based on it. When the judgment result is no, the digital control circuit 622 returns to step S810. When the judgment result is yes, the digital control circuit 622 executes the battery disconnection detection procedure (as shown in step S820).

[0038] The battery disconnection detection procedure includes the following steps: First, the digital control circuit 122 alternately performs the first operation and the second operation on the pulse width modulation signal (as shown in step S822). The first operation is to increase the duty cycle of the pulse width modulation signal by a first default value and last for a first default time. Since the output of the charging circuit 614 is also used as a system power supply, in this example, the first default value is increased to 35%. Assuming that the original duty cycle of the pulse width modulation signal is 50%, the adjusted duty cycle is 85%. In addition, the second operation is to restore the original duty cycle of the pulse width modulation signal and last for a second default time. In this example, the duty cycle of the pulse width modulation signal is adjusted back from 85% to 50%.

[0039] In this example, the first default time is 10 milliseconds, and the second default time is 30 milliseconds, but this is not intended to limit the present invention. For example, for different models of offline uninterruptible power supply systems, the first default time may also be greater than or equal to 1 second, and the second default time may also be greater than or equal to 2 seconds. In addition, in the case where the output of the charging circuit 614 is also used as a system power supply, the preferred value of the first default value is greater than or equal to 35%, but this is not intended to limit the present invention. In addition, in step S822, the digital control circuit 622 will also stop the function of stabilizing the output voltage of the charging circuit 614 during the first default time.

[0040] Please refer to Figure 6 and Figure 8. Since the duty cycle of the PWM signal is used to control the output voltage of the charging circuit 614, by alternately performing the first operation and the second operation on the PWM signal, the charging circuit 614 can output some additional energy. When the first default value, the first default time, and the second default time are properly designed, if the battery 116 is not disconnected, the additional energy output by the charging circuit 614 will be absorbed by the battery 116, so the voltage V4 at the output end of the charging circuit 614 will not rise. On the contrary, if the battery 116 is disconnected, the additional energy output by the charging circuit 614 cannot be absorbed by the battery 116, so the voltage V4 at the output end of the charging circuit 614 will rise.

[0041] As described above, after executing step S822, the digital control circuit 622 will determine whether the voltage at the output end of the charging circuit 614 rises and reaches the second default value (as shown in step S824) based on the sensing result output by the sensing circuit 118. When the voltage V4 at the output end of the charging circuit 614 reaches the second default value, the digital control circuit 622 stops executing the first operation and the second operation, and increases the duty cycle of the pulse width modulation signal so that the target voltage magnitude of the output voltage of the charging circuit 614 rises to the third default value and maintains the third default time (as shown in step S826). The third default value is greater than the second default value. In addition, the third default time is, for example, 1 second. The reason why the target voltage magnitude of the output voltage of the charging circuit 614 is raised to the third default value is mainly because there are other loads consuming system power, so that even if the voltage V4 at the output end of the charging circuit 614 rises to the second default value, it will soon drop again and cannot be maintained at the second default value, resulting in an inability to determine whether the battery 116 is disconnected.

[0042] After executing step S826, the digital control circuit 622 will determine whether the voltage V4 at the output end of the charging circuit 614 still reaches the second default value within the third default time (as shown in step S828). When it is determined that the voltage V4 at the output end of the charging circuit 614 reaches the second default value within the third default time, the digital control circuit 622 determines that the battery 116 is disconnected (as shown in step S830). On the contrary, when it is determined that the voltage V4 at the output end of the charging circuit 614 does not reach the second default value within the third default time, the digital control circuit 622 determines that the battery 116 is not disconnected (as shown in step S832). Once the digital control circuit 622 determines that the battery 116 is not disconnected, the digital control circuit 622 restores the output voltage of the charging circuit 614 to the original target voltage (as shown in step S834), and then returns to step S822.

[0043] In addition, in step S824, if the result of the determination is negative, the digital control circuit 622 will also determine that the battery 116 is not disconnected (as shown in step S832). Then, the digital control circuit 622 will restore the original target voltage of the output voltage of the charging circuit 614 (as shown in step S834). Since the target voltage of the output voltage of the charging circuit 614 is not changed in steps S822, S824 and S832, the target voltage of the output voltage of the charging circuit 614 will not be changed in step S834.

[0044] Fig. 9 That is, it is used to illustrate the change of the voltage V4 at the output end of the charging circuit 614. Fig. 9 As shown, when the additional energy output by the charging circuit 614 cannot be absorbed by the battery 116, the voltage V4 at the output end of the charging circuit 614 will rise (as shown by the mark 902). When the voltage V4 at the output end of the charging circuit 614 reaches the second default value, the digital control circuit 622 stops executing the first operation and the second operation, and causes the target voltage of the output voltage of the charging circuit 614 to rise to the third default value and maintain the third default time, and the result is shown by the mark 904. Therefore, as long as the voltage V4 at the output end of the charging circuit 614 still reaches the second default value within the third default time, it can be determined that the battery 116 is disconnected. Once it is determined that the battery 116 is disconnected, the charging circuit 614 can be turned off to avoid wasting energy. Therefore, the voltage V4 at the output end of the charging circuit 614 will begin to drop.

[0045] It is worth mentioning that, in a preferred embodiment, the voltage difference between the third default value and the second default value is equal to the voltage difference between the second default value and the original target voltage of the output voltage of the charging circuit 614. Assuming that the original target voltage of the output voltage of the charging circuit 614 is set to 55.2V, and the second default value is set to 56V, then the third default value is preferably set to 56.8V to more effectively detect the additional energy output by the charging circuit 614.

[0046] Please refer to Figure 6 and Figure 8In order to further determine whether the battery 116 is fully charged or nearly fully charged, in step S810, the digital control circuit 622 can not only determine whether the charging circuit 614 is in the constant voltage charging mode, but also further determine whether the charging current output by the charging circuit 614 is less than the default current value (for example, 0.3 amperes, but this is not intended to limit the present invention) based on the sensing result output by the sensing circuit 118. When both are judged to be yes, the digital control circuit 622 executes the battery disconnection detection procedure. Of course, for different models of offline uninterruptible power systems, the default current value can also be other values, such as 0.5 amperes. In general, the default current value can be set to the current size when the charging circuit 614 enters the float charging state.

[0047] It is worth mentioning that although the above embodiments are based on online uninterruptible power systems and offline uninterruptible power systems, this is not intended to limit the present invention. Those skilled in the art should know that the method of the present invention can also be applied to online interactive uninterruptible power systems (line-interactive uninterruptible power systems, line-interactive UPS) and even to other electronic devices.

[0048] In summary, since the method of the present invention alternately performs the first operation and the second operation on the pulse width modulation signal used to control the output voltage of the charging circuit when the charging circuit is in the constant voltage charging mode, and determines whether the battery is disconnected based on the voltage change at the output end of the charging circuit, it can solve the problem of the conventional technology that the battery cannot be detected when the battery is fully charged or nearly fully charged.

[0049] The embodiments described above are only for illustrating the technical ideas and features of the present invention, and their purpose is to enable people skilled in the art to understand the content of the present invention and implement it accordingly. They cannot be used to limit the patent scope of the present invention. That is, any equivalent changes or modifications made according to the spirit disclosed by the present invention should still be included in the patent scope of the present invention.

Claims

1. A method for detecting whether a battery is disconnected, characterized in that: The method comprises: Determining whether a charging circuit for charging a battery is in a certain voltage charging mode; and When the judgment is yes, a battery disconnection detection program is executed, and the battery disconnection detection program includes: Alternately performing a first operation and a second operation on a pulse width modulation signal, wherein the duty cycle of the pulse width modulation signal is used to control the output voltage of the charging circuit, the first operation is to increase the duty cycle of the pulse width modulation signal by a first default value and last for a first default time, and the second operation is to restore the original duty cycle of the pulse width modulation signal and last for a second default time; and It is determined whether the voltage at the output end of the charging circuit rises and reaches a second default value.

2. The method for detecting whether a battery is disconnected according to claim 1, characterized in that: The method further includes determining whether the magnitude of the charging current output by the charging circuit is less than a default current value, and executing the battery disconnection detection procedure when the determination is yes.

3. The method for detecting whether a battery is disconnected according to claim 2, characterized in that: The default current value is 0.3 amps.

4. The method for detecting whether a battery is disconnected according to claim 1, characterized in that: The first default time is 10 milliseconds, and the second default time is 30 milliseconds.

5. The method for detecting whether a battery is disconnected according to claim 1, characterized in that: The first default value is 0.6%-1%.

6. The method for detecting whether a battery is disconnected according to claim 5, characterized in that: When the voltage at the output end of the charging circuit reaches the second default value, it is determined that the battery is disconnected, and when the voltage at the output end of the charging circuit does not reach the second default value, it is determined that the battery is not disconnected.

7. The method for detecting whether a battery is disconnected according to claim 1, characterized in that: The output end of the charging circuit is further electrically coupled to at least one load, and the first default value is greater than or equal to 35%.

8. The method for detecting whether a battery is disconnected according to claim 7, characterized in that: The method further includes stopping stabilizing the output voltage of the charging circuit during the first default time, and when the voltage at the output end of the charging circuit reaches the second default value, stopping executing the first operation and the second operation, and increasing the duty cycle of the pulse width modulation signal so that the target voltage of the output voltage of the charging circuit rises to a third default value and is maintained for a third default time, wherein the third default value is greater than the second default value.

9. The method for detecting whether a battery is disconnected according to claim 8, characterized in that: After the target voltage of the output voltage of the charging circuit is increased to the third default value, it is further determined whether the voltage at the output end of the charging circuit still reaches the second default value within the third default time. If the determination is yes, it indicates that the battery is disconnected, and if the determination is no, it indicates that the battery is not disconnected.

10. The method for detecting whether a battery is disconnected according to claim 9, characterized in that: When it is determined that the voltage at the output end of the charging circuit does not reach the second default value within the third default time, the original target voltage of the output voltage of the charging circuit is restored, and the first operation and the second operation are alternately performed again.

11. The method for detecting whether a battery is disconnected according to claim 10, characterized in that: The voltage difference between the third default value and the second default value is equal to the voltage difference between the second default value and an original target voltage of the output voltage of the charging circuit.

12. An online uninterruptible power supply system, characterized in that: The online uninterruptible power supply system includes: a charging circuit for performing a DC-DC conversion operation and for charging a battery; a sensing circuit, used to sense the output of the charging circuit and generate a sensing result; and A control unit, comprising: a digital control circuit for generating a pulse width modulation signal according to the sensing result, wherein the duty cycle of the pulse width modulation signal is used to control the output voltage of the charging circuit; and a driving circuit for generating a driving signal according to the pulse width modulation signal to drive the charging circuit, When the digital control circuit determines that the charging circuit is in a certain voltage charging mode according to the sensing result, the digital control circuit executes a battery disconnection detection procedure. The steps of the battery disconnection detection procedure include: Alternately performing a first operation and a second operation on the PWM signal, wherein the first operation is to increase the duty cycle of the PWM signal by a first default value and last for a first default time, and the second operation is to restore the original duty cycle of the PWM signal and last for a second default time; and It is determined whether the voltage at the output end of the charging circuit rises and reaches a second default value.

13. The online uninterruptible power supply system according to claim 12, characterized in that: The digital control circuit further determines whether the charging current output by the charging circuit is smaller than a default current value according to the sensing result, and executes the battery disconnection detection procedure when the value is determined to be yes.

14. The online uninterruptible power supply system according to claim 13, characterized in that: The default current value is 0.3 amps.

15. The online uninterruptible power supply system according to claim 12, characterized in that: The first default time is 10 milliseconds, and the second default time is 30 milliseconds.

16. The online uninterruptible power supply system according to claim 12, characterized in that: The first default value is 0.6%-1%.

17. The online uninterruptible power supply system according to claim 16, characterized in that: When the voltage at the output end of the charging circuit reaches the second default value, the digital control circuit determines that the battery is disconnected, and when the voltage at the output end of the charging circuit does not reach the second default value, the digital control circuit determines that the battery is not disconnected.

18. An offline uninterruptible power supply system, characterized in that: The offline uninterruptible power supply system includes: a charging circuit for performing an AC-DC conversion operation, wherein the output of the charging circuit is used to charge a battery and is used as a system power supply; a sensing circuit, used to sense the output of the charging circuit and generate a sensing result; and A control unit, comprising: a digital control circuit for generating a pulse width modulation signal according to the sensing result, wherein the duty cycle of the pulse width modulation signal is used to control the output voltage of the charging circuit, wherein the digital control circuit also has the function of stabilizing the output voltage of the charging circuit; and a driving circuit for generating a driving signal according to the pulse width modulation signal to drive the charging circuit, When the digital control circuit determines that the charging circuit is in a certain voltage charging mode according to the sensing result, the digital control circuit executes a battery disconnection detection procedure. The steps of the battery disconnection detection procedure include: Alternately performing a first operation and a second operation on the pulse width modulation signal, wherein the first operation is to increase the duty cycle of the pulse width modulation signal by a first default value and last for a first default time, and to stop the function of stabilizing the output voltage of the charging circuit during the first default time, and the second operation is to restore the original duty cycle of the pulse width modulation signal and last for a second default time; Determining whether the voltage at the output end of the charging circuit rises and reaches a second default value; When the voltage at the output end of the charging circuit reaches the second default value, the first operation and the second operation are stopped, and the duty cycle of the pulse width modulation signal is increased so that the target voltage of the output voltage of the charging circuit rises to a third default value and is maintained for a third default time, wherein the third default value is greater than the second default value; and It is determined whether the voltage at the output end of the charging circuit still reaches the second default value within the third default time.

19. The off-line uninterruptible power supply system according to claim 18, characterized in that: The digital control circuit further determines whether the charging current output by the charging circuit is smaller than a default current value according to the sensing result, and executes the battery disconnection detection procedure when the value is determined to be yes.

20. The off-line uninterruptible power supply system according to claim 19, characterized in that: The default current value is 0.3 amps.

21. The off-line uninterruptible power supply system according to claim 18, characterized in that: The first default time is 10 milliseconds, and the second default time is 30 milliseconds.

22. The off-line uninterruptible power supply system according to claim 18, characterized in that: The first default value is greater than or equal to 35%.

23. The off-line uninterruptible power supply system according to claim 18, characterized in that: When it is determined that the voltage at the output end of the charging circuit reaches the second default value within the third default time, the digital control circuit determines that the battery is disconnected, and when it is determined that the voltage at the output end of the charging circuit does not reach the second default value within the third default time, the digital control circuit determines that the battery is not disconnected.

24. The off-line uninterruptible power supply system according to claim 23, characterized in that: When it is determined that the voltage at the output end of the charging circuit does not reach the second default value within the third default time, the digital control circuit restores the original target voltage of the output voltage of the charging circuit and re-alternates the first operation and the second operation.

25. The off-line uninterruptible power supply system according to claim 24, characterized in that: The voltage difference between the third default value and the second default value is equal to the voltage difference between the second default value and an original target voltage of the output voltage of the charging circuit.

Images