CN116068250A

CN116068250A - Realization method for improving temperature stability of shunt

Info

Publication number: CN116068250A
Application number: CN202111297177.9A
Authority: CN
Inventors: 刘青峰; 彭永良
Original assignee: Shenzhen Chaoda Investment Partnership LP
Current assignee: Shenzhen Huada New Energy Technology Co ltd
Priority date: 2021-11-04
Filing date: 2021-11-04
Publication date: 2023-05-05

Abstract

The invention discloses an implementation method for improving the temperature stability of a shunt, which comprises the shunt, a heating module, a temperature detection module, a temperature reference and a control module; the temperature detection module and the heating module are close to the temperature detection module, the output of the temperature detection module and the temperature reference are used as the input of the control module, and the output of the control module controls the heating module. By stabilizing the temperature of the shunt at a relatively high but deterministic value, the nonlinear effects of temperature drift of the shunt during current sensing are eliminated and the resistance of the shunt is stabilized.

Description

Realization method for improving temperature stability of shunt

Technical Field

The invention relates to an implementation method for improving the temperature stability of a shunt.

Background

The current accuracy of the current divider with a general structure is higher when the current divider is used for measuring a low-power loop, but the accuracy of measuring a high current is greatly reduced; the main factors affecting accuracy are temperature, including ambient temperature, and also including the shunt itself, and when a large current is passed, the temperature rise caused by ohmic heat of the resistor affects the resistance, and the resistance changes with temperature change, i.e. temperature drift.

In the measurement step, the linearity error can be eliminated by checking, but the TCR of the shunt is nonlinear, and if the piecewise check is performed, a great deal of effort is added.

Disclosure of Invention

The invention relates to a novel high-stability shunt realization method; according to the method, the influence of ambient temperature and passing current on the resistance of the shunt can be eliminated, so that a determined resistance is calibrated after verification is performed.

The invention eliminates or reduces the resistance change caused by temperature drift generated by the environment and the heating of the resistor by controlling the temperature of the shunt body at a relatively high fixed value.

Drawings

The invention will be further described with reference to the drawings and examples.

FIG. 1 is an implementation of a constant shunt temperature.

FIG. 2 is an electrical schematic diagram of one specific closed loop control.

Detailed Description

Hereinafter, some embodiments of the present disclosure will be described in detail with reference to the attached illustrative drawings. Where elements of the drawings are designated by reference numerals, the same elements will be designated by the same reference numerals although the same elements are illustrated in different drawings. Further, in the following description of the present disclosure, a detailed description of known functions and configurations incorporated herein will be omitted where it may make the subject matter of the present disclosure unclear.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular is intended to include the plural unless the context indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes," and/or "having," when used in this specification, are intended to specify the presence of stated features, entities, operations, and/or components, but do not preclude the presence or addition of one or more other features, entities, operations, and/or components.

Unless defined otherwise, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this inventive concept belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. The present disclosure may be practiced without some or all of these specific details. In other instances, only components that are germane to schemes according to the present disclosure have been shown in the drawings, while other details that are not germane to the present disclosure have been omitted in order to avoid obscuring the present disclosure with unnecessary detail.

The core idea of the disclosed technology is to detect the temperature of the shunt during operation, then control a heater in a closed loop manner, and stabilize the temperature of the shunt body at a relatively high but constant temperature, thereby eliminating the temperature drift of the shunt resistance.

The invention is further described below with reference to the drawings and detailed description.

As shown in fig. 1, the implementation of the present invention includes a general shunt 100, a circuit board 101, a heating module 102, a temperature detection module 103, a temperature reference 104, and a control module 105. The circuit board 101 provides mounting support for other components, the heating module is attached to the heat sink 101, and the temperature sensing module 103 is also located as close as possible to the shunt 100. If the current through the shunt 100 is maximum at the time when the heating module 102 is not operating, the ambient temperature is maximum, the temperature detection module 103 tests the temperature at this time, assuming T0, then the value of the temperature reference is set to a value higher than T0, such as T1, and then the control module 105 compares the reading of the temperature detection module 103 with T1, and the heating module 102 is closed-loop controlled to stabilize the temperature of the separator around T1. Because T1 is greater than T0, the heating module 102 may need to operate at all times and adjust the output power based on operating conditions. Therefore, the maximum output power of the heater can still stabilize the reading of the temperature detection module at T1 under the conditions of minimum current (e.g., 0) flowing through the shunt, minimum ambient temperature, and the like.

Because the temperature of the shunt 100 is a fixed value under any operating conditions, the resistance does not drift with the environment.

As a specific example of control, fig. 2 illustrates a specific implementation of a control circuit, where 201 is a switch for control, such as a MOSFET,202 is a resistor for a heater, 200 is an NTC temperature detection device, NTC 200 and heater 202 are both close to a shunt whose accuracy of resistance is to be controlled, the resistance of 200 varies with the temperature of the shunt, and a comparison network is formed with

resistor

204, 203 is a digital processing unit (DSP) that samples the voltage between 200 and 203; if the temperature of the shunt is too high, the resistance of 200 is reduced, the voltage division value detected by 203 (DSP) is high, and a pulse signal with a smaller duty ratio is generated to switch 201 according to the voltage division value, so that the power of the heater 202 is reduced, and the temperature of the shunt is reduced; and vice versa.

According to the actual test result, a shunt with a nominal resistance of 0.05 milliohms and a full scale of 200A is realized by the method, and the resistance can be stabilized within two parts per million of the full scale when the current flowing from 0 to 200A at room temperature.

While the disclosure has been disclosed by the foregoing description of specific embodiments thereof, it will be understood that various modifications, improvements, or equivalents may be devised by those skilled in the art that will fall within the spirit and scope of the appended claims. Such modifications, improvements, or equivalents are intended to be included within the scope of this disclosure.

Claims

1. The realization method for improving the temperature stability of the shunt comprises the shunt, a heating module, a temperature detection module and a temperature reference and control module; the heater is close to the shunt, the temperature detection module is close to the shunt, the output of the temperature detection module and the temperature reference are used as the input of the control module, and the output of the control module is connected to the heating module.

2. The method according to claim 1, wherein the control module controls the output power of the heating module according to the measured result of the temperature detection module, so as to stabilize the temperature of the shunt at a certain temperature or control the variation range of the temperature to be less than 10 ℃.

3. The method of claim 1, wherein the minimum output power of the heating module is required to meet all working conditions requiring the accuracy index of the shunt to be met, the shunt is heated by the minimum output power, and the temperature detected by the temperature detection module can be stabilized at a determined temperature, or the temperature variation range is controlled to be less than 10 ℃.

4. The method of claim 1, further comprising adding a heat sink or other auxiliary heat dissipation means between the heating module and the shunt.

5. The method of claim 4, wherein the target stable temperature of the shunt can be different determined values under different working environments when the environmental conditions are complex.