Low-power-consumption battery overcharge protection circuit

Abstract

The invention relates to a charging control circuit. The technology can be applied to charging control of an energy storage element in a low-power-consumption system. The field-effect tube is used as a control switch to control on and off of a charging function, the comparator is used for controlling on and off of the field-effect tube, a voltage threshold value of charging cut-off is set in a resistance voltage division mode, and the comparator is used as a core of a control circuit. And determining the opening and closing of the charging function according to the input voltage value of the current energy storage element. The innovation point of the invention is that battery overcharge protection is realized under the condition of ultra-low power consumption.

Description

TECHNICAL FIELD

[0001] The present application relates to a charging control circuit, which is applied to the charging control of energy storage elements in low-power systems, and can also be applied to other charging circuit controls with the same or similar requirements. BACKGROUND

[0002] Currently, low-power systems in the industry are generally powered by batteries. Since the use of batteries has a lifespan limit, it is necessary to collect environmental energy to compensate for the battery and improve the service life of the battery. Environmental energy generally includes solar energy, vibration energy, electromagnetic energy, etc. After the environmental energy is collected into the system, it has two uses, one is for the work of the micro-power main system, and the other is for energy storage (usually using a battery). Environmental energy is usually very weak, and the energy obtained from the collection mechanism is usually in the order of microwatts. Traditional charging control circuits belong to milliamperes of current control and are not suitable for low-power applications. There is no mature solution for micro-ampere level charging protection control in the industry. If there is no overcharge protection during battery charging, it will cause the battery to catch fire and explode, so the overcharge protection circuit is necessary.

[0003] The micro-ampere level overcharge protection control technology proposed by the present application is a technology with extremely low power consumption, extremely low cost and high reliability. The present application fills the gap in the field of environmental energy harvesting (Energy Harvesting) and micro-ampere level battery overcharge protection control technology. SUMMARY

[0004] (I) Invention purpose In order to solve the micro-ampere level charging control circuit under the current technical conditions, the charging energy path control scheme, the energy storage element voltage detection scheme, the charging management scheme and other auxiliary line schemes are involved. The technology has low cost, high reliability and low function. The present application fills the gap in the field of micro-ampere level charging control.

[0005] (II) Technical scheme The main technical solution of the low-power circuit with microampere-level charging control circuit provided by the present invention is as follows: (1) The voltage of the energy storage element (generally a battery or supercapacitor) is detected in real time by using a resistor voltage divider. The threshold of the conditional charging circuit switch is adjusted by adjusting the voltage divider resistors (R1, R2) to adapt to different energy storage elements. (2) The voltage value after voltage division is connected to pin 3 (point A) of the comparator (U1) and compared with the voltage value of pin 4 (fixed voltage VCC, point B). When the voltage at point A is higher than the voltage at point B, pin 1 (point C) of the comparator (U1) outputs a high level. When the voltage at point A is lower than the voltage at point B, pin 1 (point C) of the comparator (U1) outputs a low level. (3) The auxiliary component field-effect transistor (Q1) is used to adjust the output level of pin 1 (point C) of the comparator. When point C is high, the field-effect transistor Q1 is turned on and point D is high. When point C is low, the field-effect transistor Q1 is turned off and point D is high. (4) Field-effect transistor Q2 is a charging control switch, which is controlled by the level of point D to turn on and off. When point D is high, Q2 is turned on and charging is allowed. When point D is low, Q2 is turned off and charging is stopped. Attached Figure Description

[0006] Figure 1 Diagram illustrating overcharge protection for low-power batteries: U1: Comparator; R1, R2, R3, R4, R5, R6: Resistors; Q1, Q2: Field-effect transistors; BT1: Energy storage element Detailed Implementation

[0007] The present invention will now be described in further detail with reference to the accompanying drawings: like Figure 1 As shown, this invention provides a microampere-level charging control circuit for a low-power circuit, including an energy storage element detection circuit, a comparison control circuit, a charging switch control circuit, and auxiliary circuits.

[0008] Figure 1 In the diagram, CHARGEIN represents the external energy input, which may come from, but is not limited to, one or more of the following: small-power solar power generation equipment, small-power wind power generation equipment, small-power wave power generation equipment, vibration energy harvesting equipment, electromagnetic wave energy harvesting equipment, Rogowski coil current transformer, etc. The external energy is preprocessed into a form acceptable to the energy storage element through voltage multiplication, rectification, and other methods; BATIN represents the voltage of the energy storage element; BT1 represents the energy storage element; R6 is a current-limiting resistor, used to limit the charging current of the energy storage element to prevent damage to the energy storage element caused by directly charging it when the external input is too large; U1 is a comparator; A, B, C, and D are four test points for describing the circuit components.

[0009] In the circuit, R1 and R2 are voltage divider resistors. BATIN, after voltage division, yields the voltage at point A, which serves as the non-inverting input of the comparator. The voltage at point B is the inverting input of the comparator, a fixed value VCC. When the voltage at point A is higher than the voltage at point B, pin 1 (point C) of the comparator (U1) outputs a high level. At this time, auxiliary component Q1 is turned on, and point D is at a low level. Charging control component Q2 is then turned off, stopping charging and thus protecting the energy storage device. When the voltage at point A is higher than the voltage at point B, pin 1 (point C) of the comparator (U1) outputs a low level. At this time, auxiliary component Q1 is turned off, and point D is at a high level. Charging control component Q2 is then turned on, resuming the charging function.

Claims

1. A charging circuit protection for ultra-low power design, its main function is to actively shut down the charging circuit when the energy storage element voltage reaches or exceeds the set threshold, to prevent damage to the energy storage element due to overcharging; at the same time, when the voltage of the energy storage element is lower than the set threshold, the charging circuit is automatically turned on to allow continuous charging. The entire circuit is composed of a comparator (U1), an energy storage element voltage detection and regulation element (R1, R2), a power switch element (Q2), an auxiliary control element (Q1), and other auxiliary elements, which can ensure the normal operation and stable performance of the circuit.

2. The charge control circuit according to claim 1, characterized by: The circuit described uses a comparator (U1) as the core control element, the voltage at pin 4 (point B) of the comparator is fixed at VCC, the voltage at pin 3 (point A) of the comparator is the value of the energy storage element detection voltage (VATIN) after a certain proportion of voltage division, and the voltage at pin 1 (point C) of the comparator is the output, which is the comparison value of the voltages at points A and B. When the voltage at point A is higher than the voltage at point B, the output at point C is high; when the voltage at point A is lower than the voltage at point B, the output at point C is low.

3. The charge control circuit according to claim 1, characterized by: The voltage of the energy storage device (VATIN) is detected using a resistive voltage divider (R1, R2), and by adjusting the values of R1 and R2, the voltage of different energy storage elements can be adapted, i.e. the voltage at point A is determined by the resistance values of R1 and R2 and the voltage of the energy storage element (VATIN).

4. The charge control circuit according to claim 1, characterized by: A P-channel field effect transistor (Q2) is used as a charging switch, which has extremely low drain current, much smaller than the controlled current (microampere level), which can ensure reliable shutdown when needed.

5. The charge control circuit according to claim 1, 2, 4, characterized by: Auxiliary device Q1 is used as a polarity adjustment element between the comparator and the charging switch (P-channel field effect transistor Q2), to ensure the correctness of the control logic between the comparator (U1) and the charging switch (Q2).

6. The charge control circuit according to claims 1 to 5, characterized by: Multiple auxiliary elements are used in conjunction with the corresponding functional circuits to perform functions such as current limiting, protection, pull-up, and pull-down, ensuring the normal operation of each functional module.

7. The charge control circuit according to claims 1 to 6, characterized by: The energy sources for the charging control circuit include but are not limited to the following low-power power supplies: small-power solar power generation equipment, small-power wind power generation equipment, small-power wave power generation equipment, vibration energy harvesting equipment, electromagnetic wave energy harvesting equipment, and Rogowski coil current transformers.

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