A dual channel residual current sensor

Abstract

The application discloses a kind of double-channel residual current sensors, belong to sensor field, including magnetic core, two coils, constant current source module, MCU module, acquisition conversion module;Acquisition conversion module includes oscillation circuit, current acquisition circuit and current-to-voltage circuit;Two magnetic cores are wound on the magnetic core, and one coil is used to participate in current oscillation and current-to-voltage, another coil provides a constant test current by constant current source module;MCU module is used for interval control constant current source module output one superimposed current and is used for the acquisition and processing of current signal transmitted by acquisition conversion module.The beneficial effects of the application are simple circuit, small size, low failure rate and low cost.

Description

Technical Field

[0001] This invention relates to current sensors, and more specifically, to a dual-channel residual current sensor. Background Technology

[0002] In the field of automotive charging, on-board charging protection sensors need to meet the ISO26262 standard, one of which requires dual-channel mutual verification. The mainstream method in the market is to design two completely independent sensors. When the current collected by the two sensors is inconsistent or has a large deviation, or when neither sensor can collect a current, a device fault alarm is triggered.

[0003] Therefore, its shortcomings are:

[0004] 1. Since two sensors are used, mutual verification between the two channels requires an external control board.

[0005] 2. Large size: The size is twice that of a single sensor. Many charging cables are small control boxes with a lot of cramped space. In addition, the number of components for the two sensors has also increased by half, naturally increasing the failure rate.

[0006] 3. High cost: Combining two sensors into one naturally doubles the cost. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a dual-channel residual current sensor that solves the above-mentioned technical problems.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A dual-channel residual current sensor, characterized in that it includes a magnetic core, two coils, a constant current source module, an MCU module, and a data acquisition and conversion module;

[0010] The data acquisition and conversion module includes an oscillation circuit, a current acquisition circuit, and a current-to-voltage conversion circuit.

[0011] Both magnetic cores are wound around the magnetic core, and one coil is used to participate in current oscillation and current-to-voltage conversion, while the other coil is provided with a constant test current through a constant current source module;

[0012] The MCU module is used to control the constant current source module to output a superimposed current and to acquire and process the current signal transmitted by the acquisition and conversion module.

[0013] Furthermore, the acquisition and conversion module includes a PWM mode and a VO analog signal mode for current acquisition. The PWM mode is a duty cycle signal, and the VO analog signal mode is an analog signal.

[0014] The MCU module acquires the duty cycle signal through the PWM circuit and the analog signal through the ADC circuit, and triggers and verifies the acquired data respectively.

[0015] Furthermore, the MCU module is used to perform modulus division and amplitude limiting of the acquired data, DC separation, and to integrate and store the DC component;

[0016] The MCU module is used to store the signal after it has undergone modulus reduction and amplitude limiting, followed by RMS calculation and integration.

[0017] Furthermore, the data after amplitude limiting is phase-shifted by 120 degrees and superimposed with the original data to form a virtual waveform, which is used to distinguish between DC and mixed waves.

[0018] Furthermore, the MCU module compares the similarity of the RMS signals in PWM mode and VO analog signal mode. When the two signals are similar, a trigger judgment is made, and the AC PWM outputs a trigger result of 90% or 10%.

[0019] Furthermore, the MCU module compares the similarity of the DC integral signals in PWM mode and VO analog signal mode. When the two signals are similar, a trigger judgment is made, and then the DC PWM outputs a trigger result of 90% or 10%.

[0020] Furthermore, DC triggering requires confirmation that it is DC before it can be triggered.

[0021] By adopting the above technical solution, the beneficial effects of the present invention are as follows:

[0022] 1. Simple circuit: Except for current and voltage conversion and constant current source, all other processing is completed within a single MCU, requiring few external components, and most functions are implemented through software;

[0023] 2. Small size: Because only one sensor is needed to perform the functions of two sensors, and it also has the function of comparing the similarity of the signal analog quantities of the external main control board, not only is the size smaller, but the cost is also only half.

[0024] 3. The sensor section has integrated two-channel mutual verification and trigger condition judgment, so the external control board no longer needs to be designed with trigger condition judgment, which greatly simplifies the design of the external control board. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention.

[0026] Figure 2 This is a flowchart of the data processing process. Detailed Implementation

[0027] Reference Figures 1 to 2 The embodiments of the present invention will be further described below.

[0028] Specific implementation schemes of the present invention: such as Figure 1 As shown, the sensor's magnetic core is wound with two coils. One coil is used to participate in chip oscillation and current conversion, and the other coil provides a constant test current through a constant current source. Normally, only the oscillation coil is working. To prevent sensor malfunctions from going undetected, the IC3 MCU will periodically control IC2 to output a superimposed current. This superimposed current is superimposed on the original measured current and then converted and acquired through the oscillation coil and IC1. After the MCU acquires the superimposed current, it subtracts it from the original current. When the subtraction result matches the output of the constant current source, it indicates that the sensor's current conversion part is normal.

[0029] The current acquisition consists of two methods: PWM mode and VO analog signal. The MCU acquires current using both PWM and ADC methods. The acquired data needs to be triggered and cross-verified separately. The data processing flowchart is as follows. Figure 2 .

[0030] 4. Signal Processing Instructions:

[0031] (1) The Vo analog signal mode is an analog signal, which is acquired by the MCU ADC circuit. After the analog signal is divided and the amplitude is limited, the DC component is separated, integrated and stored. The signal after the analog signal is divided and the amplitude is limited, and the signal after the RMS operation and integration is stored.

[0032] (2) PWM mode is a duty cycle signal, which is acquired by the MCU PWM circuit. The acquired data is separated into DC and DC components after being divided by modulus and limited. The DC component is integrated and stored. The signal after being divided by modulus and limited is then stored after being processed by RMS and integrated.

[0033] (3) After the data is limited, it is phase-shifted by 120 degrees and then superimposed with the original data to form a virtual waveform. This virtual waveform is used to distinguish between DC and mixed waves.

[0034] (4) The similarity of the RMS signals of the two channels is compared. When the two signals are similar, a trigger judgment is made and the ACPWM outputs the trigger result of 90% or 10%.

[0035] (5) The DC integral signals of the two channels are compared for similarity. When the two signals are similar, a trigger judgment is made and the trigger result of 90% or 10% is output by DCPWM.

[0036] (6) DC triggering requires confirmation that it is DC before it can be triggered.

[0037] (7) The magnetic core conversion section is controlled by the MCU to perform superposition test of the test current by the constant current chip at intervals.

[0038] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any ordinary changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included within the protection scope of the present invention.

Claims

1. A dual-channel residual current sensor, characterized in that, Includes a magnetic core, two coils, a constant current source module, an MCU module, and a data acquisition and conversion module; The data acquisition and conversion module includes an oscillation circuit, a current acquisition circuit, and a current-to-voltage conversion circuit. Both magnetic cores are wound around the magnetic core, and one coil is used to participate in current oscillation and current-to-voltage conversion, while the other coil is provided with a constant test current through a constant current source module; The MCU module is used to control the constant current source module to output a superimposed current and to acquire and process the current signal transmitted by the acquisition and conversion module. The MCU module is used to perform modulus division and amplitude limiting of the acquired data, DC separation, integration of the DC component, and storage. The MCU module is used to store the signal after modulus reduction and amplitude limiting, followed by RMS calculation and integration. The data after amplitude limiting is phase-shifted by 120 degrees and superimposed with the original data to form a virtual waveform. This virtual waveform is used to distinguish between DC and mixed waves.

2. A dual-channel residual current sensor according to claim 1, characterized in that, The acquisition and conversion module includes a PWM mode and a VO analog signal mode for current acquisition. The PWM mode is a duty cycle signal, and the VO analog signal mode is an analog signal. The MCU module acquires the duty cycle signal through the PWM circuit and the analog signal through the ADC circuit, and triggers and verifies the acquired data respectively.

3. A dual-channel residual current sensor according to claim 1, characterized in that, The MCU module compares the similarity of the RMS signals in PWM mode and VO analog signal mode. When the two signals are similar, a trigger judgment is made and the AC PWM outputs a trigger result of 90% or 10%.

4. A dual-channel residual current sensor according to claim 1, characterized in that, The MCU module compares the similarity of the DC integral signals in PWM mode and VO analog signal mode. When the two signals are similar, a trigger judgment is made and the DC PWM outputs a trigger result of 90% or 10%.

5. A dual-channel residual current sensor according to claim 4, characterized in that, DC triggering requires confirmation that it is DC before it can be triggered.

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