Over-temperature protection circuit and method for charging piles

Abstract

The charging pile over-temperature protection circuit and method provided by this invention include an operational amplifier circuit, a first voltage reference circuit, a second voltage reference circuit, a voltage sampling circuit, a comparator circuit, a relay enable circuit, a power supply circuit, and a controller. The first voltage reference circuit outputs a first reference voltage to the operational amplifier circuit, and the second voltage reference circuit outputs a second reference voltage to the comparator circuit. The comparator circuit compares the output voltage of the operational amplifier circuit with the second reference voltage and controls the on / off state of the power supply circuit based on the comparison result. Simultaneously, the controller obtains the output voltage of the operational amplifier circuit through the voltage sampling circuit and compares it with a preset voltage to control the on / off state of the power supply circuit. This invention combines automatic circuit power-off with controller-controlled power-off in case of over-temperature, providing dual power-off protection. This avoids safety accidents caused by untimely or faulty single power-off methods, thus improving the reliability of the charging pile over-temperature protection circuit.

Description

Technical Field

[0001] This invention relates to the field of charging pile technology, and in particular to an over-temperature protection circuit and method for charging piles. Background Technology

[0002] In recent years, with the rapid development of the electric vehicle industry and the increasing popularity of electric vehicles, the number of charging piles used in conjunction with them has been constantly increasing, and the charging safety of electric vehicles has gradually received widespread attention. During the charging process, due to the large charging power, the temperature of the charging pile will gradually rise as the charging time increases, or for some other reason. When the temperature exceeds a certain threshold, it may cause a safety accident.

[0003] In existing technologies, the voltage is generally sensed by the ADC embedded in the charging pile controller, and the power relay is controlled by software to disconnect the charging circuit. However, if the MCU software malfunctions or encounters other faults, the charging pile cannot interrupt the charging process in time when the temperature exceeds the standard, which is not safe. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a charging pile over-temperature protection circuit and method. When the temperature is over-temperature, the circuit automatically cuts off the power and the controller controls the power off to perform a dual power-off. This avoids the safety accidents caused by the failure to cut off the power properly when the single power-off method is not timely or when there is a malfunction. The reliability of the charging pile over-temperature protection circuit is improved.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] The charging pile over-temperature protection circuit includes: an operational amplifier circuit, a first voltage reference circuit, a second voltage reference circuit, a temperature detection circuit, a voltage sampling circuit, a comparator circuit, a relay enable circuit, a power supply circuit, and a controller. The power supply circuit supplies power to the charging pile through the enable circuit. The enable circuit sends an enable signal to the power supply circuit to control the on / off state of the power supply circuit. The first voltage reference circuit outputs a first reference voltage to the positive input terminal of the operational amplifier circuit, which amplifies the first reference voltage. The temperature detection circuit is electrically connected to the negative input terminal of the operational amplifier circuit, and the amplification factor of the operational amplifier circuit is positively correlated with the temperature detected by the temperature detection circuit. The second voltage reference circuit outputs a second reference voltage to the positive input terminal of the comparator circuit. The negative input terminal of the comparator circuit is electrically connected to the output terminal of the operational amplifier circuit. The output terminal of the comparator circuit is electrically connected to the enable circuit to compare the output voltage of the operational amplifier circuit with the second reference voltage and control the on / off state of the power supply circuit based on the comparison result. The output terminal of the operational amplifier circuit is electrically connected to the voltage sampling unit. The output terminal of the voltage sampling circuit is electrically connected to the ADC port of the controller.

[0007] The output of the voltage sampling circuit is electrically connected to the controller; the controller is also electrically connected to the relay coil enable circuit, which is used to control the on / off state of the power supply circuit based on the comparison result between the output voltage of the voltage sampling circuit and the preset voltage threshold.

[0008] Specifically, the first voltage reference includes an external power supply, a resistor R1, and an adjustable resistor R2; the external power supply is electrically connected to one end of the resistor R1, and the other end of the resistor R2 is connected to the non-inverting input terminal of the operational amplifier circuit and the adjustable resistor R2, respectively, to adjust and output the voltage threshold of the over-temperature alarm according to different over-temperature alarm standards.

[0009] Furthermore, the over-temperature protection circuit of the charging pile also includes an alarm circuit, which is electrically connected to the controller; the alarm circuit includes a warning light.

[0010] Furthermore, the over-temperature protection circuit of the charging pile also includes a discharge circuit, and the coil circuit includes a capacitor. The capacitor is electrically connected to the power supply circuit and is used to release the charge in the power supply circuit through the capacitor after the power supply circuit is disconnected.

[0011] The over-temperature protection method for charging piles includes the following steps:

[0012] S1 The first voltage reference circuit provides a first reference voltage to the operational amplifier circuit. The operational amplifier circuit determines the amplification factor based on the temperature detected by the temperature detection circuit and amplifies the first reference voltage before outputting the output voltage of the operational amplifier circuit to the comparator circuit. At the same time, the voltage sampling unit acquires the output voltage of the operational amplifier circuit and sends the output voltage to the ADC port of the controller. S2 The comparator circuit compares the output voltage of the operational amplifier circuit with the second reference voltage and outputs the comparison result to the enable circuit. At the same time, the controller compares the output voltage of the operational amplifier circuit with a preset voltage threshold. S3 If the output voltage of the operational amplifier circuit is greater than the second reference voltage, that is, if the output voltage of the operational amplifier circuit is greater than the preset voltage threshold in the controller, the comparator circuit outputs a low level to the enable circuit, and the enable circuit controls the disconnection of the power supply circuit. At the same time, the controller controls the enable circuit to disconnect the power supply circuit.

[0013] The above technical solution has the following advantages or beneficial effects:

[0014] (1) When the temperature is too high, the circuit automatically cuts off the power and the controller controls the power off to perform a double power-off. This avoids the safety accident caused by the inability to cut off the power properly when the single power-off method is not timely or when there is a fault. This improves the reliability of the charging pile over-temperature protection circuit.

[0015] (2) By adjusting the voltage threshold of the over-temperature alarm according to different over-temperature alarm standards through the adjustable resistor R2, the applicability and flexibility of the charging pile over-temperature protection circuit are increased.

[0016] (3) After the charging pile is powered off due to overheating, the charge in the power supply circuit is released through the discharge circuit to prevent the circuit from burning out, which further improves the stability and safety of the charging pile overheat protection circuit. Attached Figure Description

[0017] The invention, its features, shape, and advantages will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings. Like reference numerals denote like parts throughout the drawings. The drawings are not intentionally drawn to scale; the focus is on illustrating the spirit of the invention.

[0018] Figure 1 The schematic diagram of the over-temperature protection circuit for charging piles provided by this invention. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but these are not intended to limit the scope of the invention.

[0020] Example 1:

[0021] The charging pile over-temperature protection system and method provided by this invention performs state initialization and self-test of controller 1 before charging to check for leakage, short circuit, grounding function, and normal operation of each thread of controller 1. After the charging pile is operating normally, the temperature gradually increases with the charging time. The temperature detection circuit 2 uses a temperature sensor as the feedback resistor R. f The temperature detection circuit 2 also includes a resistor R3, which is connected to the inverting input terminal of the operational amplifier circuit 3 and the feedback resistor R. f When the charger temperature is higher, R f The larger the value, the greater the amplification factor of op-amp circuit 3 is, T = R. f / R3+1, so the first reference voltage output from the first voltage reference circuit 4, after passing through the operational amplifier circuit 3, is V. o =T·V i , where V i = 3.3 × R2(R2 + R1), when the output voltage V o When the voltage is greater than the second reference voltage, comparator circuit 5 outputs a low level to enable circuit 6. Enable circuit 6 then disconnects power supply circuit 7. The voltage can be adjusted by changing the value of adjustable resistor R2. i While the above process is occurring, the voltage sampling circuit 8 acquires the output voltage of the operational amplifier circuit 3 and sends the output voltage to the ADC port 11 of the controller 1. The controller 1 compares the output voltage of the operational amplifier circuit 3 with a preset voltage threshold. If the output voltage is higher than the preset threshold, the controller 1 controls the GPIO port level of the enable circuit 6 to be pulled low, and cuts off the power supply circuit 7.

[0022] When any of the above power-off methods fails, the other method can ensure that the power supply can be cut off normally when the charging pile overheats, which greatly improves the stability and safety of the charging pile overheat protection circuit.

[0023] The preferred embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above. The devices and structures not described in detail should be understood as being implemented in a conventional manner in the art. Any person skilled in the art can make many possible changes and modifications, or equivalent changes to equivalent embodiments without departing from the technical solution of the present invention. This does not affect the substantive content of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the protection scope of the technical solution of the present invention.

Claims

1. A charging pile over-temperature protection circuit, characterized in that, include: Operational amplifier circuit, first voltage reference circuit, second voltage reference circuit, temperature detection circuit, voltage sampling circuit, comparator circuit, enable circuit, power supply circuit and controller; The power supply circuit supplies power to the charging pile through the enabling circuit; the enabling circuit sends an enabling signal to the power supply circuit to control the on / off state of the power supply circuit. The first voltage reference circuit outputs a first reference voltage to the non-inverting input terminal of the operational amplifier circuit, and the operational amplifier circuit is used to amplify the first reference voltage; the temperature detection circuit is electrically connected to the negative inverting input terminal of the operational amplifier circuit, and the amplification factor of the operational amplifier circuit is positively correlated with the temperature detected by the temperature detection circuit. The second voltage reference circuit outputs a second reference voltage to the positive input terminal of the comparator circuit; the negative input terminal of the comparator circuit is electrically connected to the output terminal of the operational amplifier circuit; the output terminal of the comparator circuit is electrically connected to the enable circuit, which is used to compare the output voltage of the operational amplifier circuit with the second reference voltage, and control the on / off state of the power supply circuit according to the comparison result. The output of the operational amplifier circuit is electrically connected to the voltage sampling circuit; the output of the voltage sampling circuit is electrically connected to the ADC port of the controller. The output of the voltage sampling circuit is electrically connected to the controller; the controller is also electrically connected to the enable circuit, which controls the on / off state of the power supply circuit based on the comparison result between the output voltage of the voltage sampling circuit and a preset voltage threshold.

2. The charging pile over-temperature protection circuit as described in claim 1, characterized in that, The first voltage reference includes an external power supply, a resistor R1, and an adjustable resistor R2; the external power supply is electrically connected to one end of the resistor R1, and the other end of the resistor R2 is connected to the non-inverting input terminal of the operational amplifier circuit and the adjustable resistor R2, respectively, for adjusting and outputting the voltage threshold of the over-temperature alarm according to different over-temperature alarm standards.

3. The charging pile over-temperature protection circuit as described in claim 1, characterized in that, It also includes an alarm circuit, which is electrically connected to the controller; the alarm circuit includes a warning light.

4. The charging pile over-temperature protection circuit as described in claim 1, characterized in that, It also includes a discharge circuit, which includes a capacitor electrically connected to the power supply circuit, for releasing the charge in the power supply circuit through the capacitor after the power supply circuit is disconnected.

5. A charging pile over-temperature protection method, based on the charging pile over-temperature protection circuit according to any one of claims 1-4, characterized in that, Includes the following steps: S1 The first voltage reference circuit provides a first reference voltage to the operational amplifier circuit. The operational amplifier circuit determines the amplification factor based on the temperature detected by the temperature detection circuit and amplifies the first reference voltage. Then, the operational amplifier circuit outputs its output voltage to the comparator circuit. At the same time, the voltage sampling circuit acquires the output voltage of the operational amplifier circuit and sends the output voltage to the ADC port of the controller. S2 The comparator circuit compares the output voltage of the operational amplifier circuit with the second reference voltage and outputs the comparison result to the enable circuit; Simultaneously, the controller compares the output voltage of the operational amplifier circuit with a preset voltage threshold. S3 If the output voltage of the operational amplifier circuit is greater than the second reference voltage, that is, the output voltage of the operational amplifier circuit is greater than the preset voltage threshold in the controller, the comparator circuit outputs a low level to the enable circuit, and the enable circuit controls the disconnection of the power supply circuit; at the same time, the controller controls the enable circuit to disconnect the power supply circuit.

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