Battery state detection circuit of charger

Abstract

The utility model provides a battery state detection circuit of a charger. The battery state detection circuit comprises a battery voltage isolation sampling circuit, an adder and a single-chip microcomputer controller. The battery voltage isolation sampling circuit collects battery voltage on the charger, attenuates the battery voltage in proportion and outputs the battery voltage in an isolation mode, the output of the battery voltage isolation sampling circuit is connected to the in-phase end of the summator, reference voltage is further connected to the in-phase end of the summator, and the output end of the summator is connected to an analog quantity input interface of the single-chip microcomputer controller through an isolation resistor. Reference voltage and battery voltage isolation sampling circuit output values are introduced to be processed by the adder and then sent to the single-chip microcomputer, it is ensured that when the battery is connected reversely, analog quantity sent to a detection port of the single-chip microcomputer is a positive value, and the single-chip microcomputer can automatically detect the polarity state and the battery voltage condition of the connected battery according to the input measured value; and charging is allowed to be started after the correct state is determined, so that loss caused by human errors is avoided.

Description

Technical Field

[0001] The utility model relates to the field of chargers, and in particular to a battery status detection circuit of a DC charger. Background Art

[0002] To ensure battery safety, the charger must test the polarity of the connected battery before starting charging. This is to prevent the polarity of the connected battery from being opposite to the high-voltage DC output polarity of the DC charger. Reverse connection can damage the charger and battery, and can even lead to serious consequences such as fire and explosion. Therefore, the polarity must be correct when connecting the charger to the battery. Currently, high-voltage voltage sampling at the battery end mostly uses proportional attenuation for analog isolation. The isolated analog input is then fed into the microcontroller's built-in ADC sampling port for digital-to-analog conversion. The actual voltage value is calculated to determine the power supply status. This solution cannot sample negative voltages, and the microprocessor cannot make a judgment if the battery is reversed, posing a safety hazard. Summary of the Invention

[0003] The purpose of this utility model is to address the above-mentioned shortcomings and design a battery status detection circuit for a charger, so that the charger can automatically detect the polarity status and battery voltage of the connected battery, and only allow charging to start after determining that the status is correct, thereby avoiding losses caused by human errors.

[0004] In order to achieve the above-mentioned purpose, the technical solution of the present utility model is:

[0005] A battery status detection circuit for a charger, comprising:

[0006] Battery voltage isolation sampling circuit, adder and single chip controller;

[0007] The battery voltage isolation sampling circuit is used to collect the battery voltage on the charger, proportionally attenuate the battery voltage and output it in isolation. The positive and negative terminals of its input are respectively connected to the positive and negative terminals of the battery output of the charger, the positive terminal of its output is connected to the non-inverting terminal of the adder, and the negative terminal of its output is grounded.

[0008] The in-phase terminal of the adder is connected to the reference voltage Vref, and the inverting terminal thereof is grounded via a resistor R1. The inverting terminal of the adder is also connected to its output terminal via a feedback resistor R2.

[0009] The output of the adder is connected to the analog input interface of the microcontroller controller through the isolation resistor R5.

[0010] Furthermore, the reference voltage Vref is a positive voltage and is greater than the maximum negative voltage output by the battery voltage isolation sampling circuit when the battery is reversely connected.

[0011] Furthermore, the reference voltage Vref is the output of the reference circuit.

[0012] Furthermore, the battery status detection circuit of the charger also includes a resistor R3 and a resistor R4. The resistor R3 is connected between the positive terminal of the output of the battery voltage isolation sampling circuit and the non-inverting terminal of the adder; the resistor R4 is connected between the non-inverting terminal of the adder and the output of the reference circuit.

[0013] Furthermore, the reference circuit is a TL431 voltage regulator or a similar device.

[0014] Furthermore, the maximum value of the output voltage of the adder is less than the maximum value voltage specified by the analog input interface of the microcontroller controller, that is, the reference voltage Vref and the maximum voltage V1 obtained by battery isolation sampling should not exceed the range of the analog input port of the microcontroller after being added by the adder.

[0015] Beneficial effects of the utility model

[0016] After the charger is used, the technical solution of the utility model can automatically detect whether the positive and negative polarity of the battery is connected correctly and the voltage value, and determine whether to start charging based on the detection results, thereby avoiding safety accidents caused by misoperation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a circuit diagram of an embodiment of the present utility model. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0019] The following combination Figure 1 The embodiment shown illustrates the working principle of the utility model:

[0020] In an embodiment of a battery status detection circuit for a charger according to the present invention, a battery voltage isolation sampling circuit has its positive and negative input terminals connected to the positive and negative output terminals of the charger's battery, respectively, for collecting the battery voltage, proportionally attenuating the battery voltage, and outputting it in isolation. The negative output terminal of the battery voltage isolation sampling circuit is grounded, and its positive output terminal is connected to the non-inverting terminal of an adder via a resistor R3. A reference voltage Vref generated by a reference circuit is also connected to the non-inverting terminal of the adder via a resistor R4. The inverting terminal of the adder is grounded via a resistor R1, and is connected to the inverting terminal of the adder and its output terminal via a feedback resistor R2. The output terminal of the adder is connected to the analog input interface of a single-chip microcomputer controller via an isolation resistor R5.

[0021] During operation, the voltage isolation sampling circuit collects the battery voltage. The attenuation multiple of the proportional voltage reduction of the voltage isolation sampling circuit is recorded as A. The actual battery voltage is V. After being processed by the isolation circuit, the output voltage V1, that is, the actual battery voltage V=AV1; the output voltage V1 of the voltage isolation sampling circuit is equal to the reference voltage V REF Connect to the adder, the output of the adder is V bat = K(V1+V REF ), k is the gain of the adder, which is related to the values ​​of resistors R1, R2, R3, and R4, then V bat = K (V1+V REF ), that is, V1=(V bat / K- V REF ), the actual battery voltage value V=AV1=A(V bat / K- V REF ).

[0022] When the battery is not connected, V1 is 0V, and the actual voltage value is V = AV1 = = 0V. At this time, the output of the adder is V bat = K(V1+V REF ), namely V bat = K*V REF , then the microcontroller controller will input V according to the analog input interface bat = K*V REF The voltage value determines that the battery is not connected, and a control signal is sent to prevent the charger from starting.

[0023] When the battery is reversed, the battery voltage is output as a negative value -V1 after being stepped down and isolated, and the adder outputs V bat = K(V REF -V1), Vref is a positive voltage and is greater than the maximum negative voltage output by the battery voltage isolation sampling circuit when the battery is reversely connected, so V bat is a positive value, which can be detected by the microcontroller controller. The actual battery voltage is: (V bat / K- V REF )×A= -A*V1, that is, the battery voltage is detected to be negative, and the microcontroller controller will output V according to the analog input interface. bat = K(V REF -V1) The voltage value determines if the battery is reversely connected and sends a control signal to prohibit the charger from starting.

[0024] When the battery is connected correctly, the battery voltage is output as a positive value V1 after step-down isolation, and the adder output V bat = K(V1+V REF ), and in actual application, the maximum value of the adder's output voltage is less than the maximum value voltage specified by the analog input interface of the microcontroller controller, that is, the reference voltage Vref and the maximum voltage V1 obtained by battery isolation sampling should not exceed the range of the microcontroller analog input port after being added by the adder. At this time, the actual battery voltage detected is: (V bat / KV REF )×A=A*V1, the value is positive and within the normal battery voltage range, the microcontroller controller will output the voltage according to the analog input interface V bat = K(V1 + VREF). The voltage value determines that the battery polarity is correct and the battery voltage is within the positive range, and the microcontroller allows the charger to start charging. The microcontroller controller issues a control signal based on the analog input interface to enable or disable charging, a function known in the art and not elaborated upon here.

[0025] Compared with traditional charger battery status detection circuits, the circuit of the utility model is simple and cost-effective. After adding the circuit of the utility model inside the charger, the battery connection status can be automatically detected and the detection is accurate, ensuring the safety of the charger battery and the charger, and avoiding safety accidents caused by charging errors.

Claims

1. A battery status detection circuit for a charger, characterized in that: include: Battery voltage isolation sampling circuit, adder and single chip controller; The battery voltage isolation sampling circuit is used to collect the battery voltage on the charger, proportionally attenuate the battery voltage and output it in isolation. The positive and negative terminals of its input are respectively connected to the positive and negative terminals of the battery output of the charger, the positive terminal of its output is connected to the non-inverting terminal of the adder, and the negative terminal of its output is grounded. The in-phase terminal of the adder is also connected to the reference voltage Vref, and the inverting terminal thereof is grounded through the resistor R1. The inverting terminal of the adder is also connected to its output terminal through the feedback resistor R2. The output of the adder is connected to the analog input interface of the microcontroller controller through the isolation resistor R5.

2. The battery status detection circuit of the charger according to claim 1, characterized in that: The reference voltage Vref is a positive voltage and is greater than the maximum negative voltage output by the battery voltage isolation sampling circuit when the battery is reversely connected.

3. The battery status detection circuit of the charger according to claim 1, characterized in that: The reference voltage Vref is the output of the reference circuit.

4. The battery status detection circuit of the charger according to claim 3, characterized in that: Also includes: It also includes a resistor R3 and a resistor R4. The resistor R3 is connected between the positive end of the output of the battery voltage isolation sampling circuit and the non-inverting end of the adder; the resistor R4 is connected between the non-inverting end of the adder and the output of the reference circuit.

5. The battery status detection circuit of the charger according to claim 3, characterized in that: The reference circuit is a TL431 voltage regulator.

6. The battery status detection circuit of the charger according to claim 1, characterized in that: The maximum value of the adder output voltage is less than the maximum value voltage specified by the analog input interface of the single chip controller.

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