CN210377199U - Novel circuit structure for improving current adoption precision by using analog circuit - Google Patents
Novel circuit structure for improving current adoption precision by using analog circuit Download PDFInfo
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- CN210377199U CN210377199U CN201921190280.1U CN201921190280U CN210377199U CN 210377199 U CN210377199 U CN 210377199U CN 201921190280 U CN201921190280 U CN 201921190280U CN 210377199 U CN210377199 U CN 210377199U
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Abstract
The utility model discloses a novel circuit structure for improving current adoption accuracy by using an analog circuit, which comprises a current sampling module, a temperature sampling module and an accuracy compensation structure; wherein, at least one comparator is connected with the temperature sampling module, the output end of the temperature sampling circuit is connected with the input end of each comparator, and the other input end of the comparator is connected with the reference voltages V1, V2, V3 and V4 … … which are not connected; the output of each comparator controls an NMOS tube to be used as a switch, the switch of a reference current is controlled, the reference current comes from the mirror image current of Iref, the output of the current sampling circuit is connected to R8, the other ends of R7 and R8 and R9 are connected to the authentication input end of an operational amplifier A1, the other end of R9 is grounded, the negative input end of the operational amplifier is connected with R10 and R11, the other end of R10 is grounded, and the other end of R11 is connected with the output of the operational amplifier and is used as the output of the whole system; the R7, R8, R9, R10, R11, and the operational amplifier a1 form an addition circuit, and the compensated error voltage is added to the output of the current sampling circuit to form a precise output.
Description
Technical Field
The utility model relates to a power electronic technology field, concretely relates to novel improve circuit structure of electric current adoption precision with analog circuit.
Background
In motor controllers, phase currents need to be sampled to achieve more accurate control. The existing current sampling mode mainly comprises resistance sampling and Hall sampling. The resistor sampling has low cost and good applicability, but the method has certain power loss and most importantly, the temperature drift of the high-power precise resistor is very serious. The other Hall sampling mode can measure large current and has small power dissipation, but although the sampling mode carries out certain temperature compensation, the sampling precision of the sampling mode is still influenced by temperature, so that the sampling precision is reduced. Therefore, in any sampling mode, if a high-precision sampling result is obtained, temperature compensation must be performed on the sampling data. Therefore, the utility model provides a method for carrying out temperature compensation through analog circuit and improving current sampling precision.
SUMMERY OF THE UTILITY MODEL
To the phenomenon that the sampling precision received the influence of temperature and took place to drift among the foretell temperature sampling scheme, the utility model provides a method for improving current sampling precision with analog circuit.
The technical scheme of the utility model is that: a novel circuit structure for improving current adoption accuracy by using an analog circuit comprises a current sampling module, a temperature sampling module and an accuracy compensation structure; wherein, at least one comparator is connected with the temperature sampling module, the output end of the temperature sampling circuit is connected with the input end of each comparator, and the other input end of the comparator is connected with the reference voltages V1, V2, V3 and V4 … … which are not connected; the output of each comparator controls an NMOS tube to be used as a switch, and controls the switch of a reference current, wherein the reference current is the mirror current of Iref; taking the first route as an example: the source end of the MP0 is connected with a power supply, and the drain end and the grid are connected with Iref to form self bias; the gate of the MP0 is connected with the gates of all the rear PMOS to form a current mirror, and the mirror proportion of the current mirror is set according to the step sizes of V1, V2, V3 and V4 … … and the errors of the temperature points represented by the step sizes; the source end of the MP1 is connected with power voltage, the drain electrode of the MP1 is connected with the drain electrode of the MN1, the source electrode of the MN1 is connected with the upper end of a resistor R12, and the grid electrode of the MN1 is connected with the output of a comparator COMP1 and is controlled by a comparator COMP 1; in the first path, V1 is connected with the positive input end of COMP1, the temperature sampling circuit is connected with the negative input end of COMP1, if the output of the temperature sampling circuit is reduced to be lower than V1 due to temperature rise, the output of the comparator is high, MN1 is conducted, and the current on MP1 is injected into R12, so that the voltage on R12 is increased; so that the value of the error compensation increases; other paths are connected according to the circuit, if the temperature rises to a certain value and the error is reduced, the compensated voltage should be reduced, so that the reference voltage corresponding to the temperature point of the temperature sampling circuit should be connected to the negative input end of the comparator, the output of the temperature sampling circuit is connected to the positive input end of the comparator, and when the temperature rises to the point, the current of the path is turned off, so that the voltage on the resistor R12 is reduced; the mirror current value of each path is set as the error voltage which should be increased or decreased relative to the previous temperature point, divided by R; if the mirror ratio of a certain cry to the reference current is 1: k, and the reference point of the way wants to have an error voltage VN with respect to the previous reference point, then:
I＝K*Iref＝VN/R12
the input of each comparator is connected in a manner dependent on whether the error compensation should be increased or decreased depending on the point at which the temperature reaches the point;
a reference current Iref1 flows in R12 firstly, namely a direct current voltage is compensated firstly, the specific value is determined according to the error condition, then the current of all branches flows in R12 to form a total error compensation voltage, and the voltage is input to the positive input end of an operational amplifier A2; the negative input end of the cloud computing amplifier A2 is connected to the output thereof and is connected to one end of the R7 to form a unity gain negative feedback, and the voltage on the R12 is not influenced by a post-stage circuit through clamping and isolation of A2; the output of the current sampling circuit is connected to R8, the other ends of R7 and R8 and R9 are connected to the authentication input end of an operational amplifier A1, the other end of R9 is grounded, the negative input end of the operational amplifier is connected with R10 and R11, the other end of R10 is grounded, and the other end of R11 is connected with the output of the operational amplifier and is used as the output of the whole system; the R7, R8, R9, R10, R11, and the operational amplifier a1 form an addition circuit, and the compensated error voltage is added to the output of the current sampling circuit to form a precise output.
The addition operation circuit is characterized in that R7, R8 and R9 are connected to the positive input end of the operational amplifier, the other end of R7 is connected with the output of the temperature sampling circuit, the other end of R8 is connected with the output of the current sampling circuit, the other end of R9 is grounded, R10 and R11 are connected with the negative input end of the operational amplifier, the other end of R10 is grounded, and the other end of R11 is connected with the output end of the operational amplifier; thus, a voltage adder is constructed.
Compared with the prior art, the current sampling circuit of the utility model can be any kind of sampling circuit such as resistance sampling, Hall current sampling, and belongs to the first input stage of the system in the scheme; the sampling result of the sampling circuit has certain error due to the influence of temperature, and is corrected by the following compensation structure.
Temperature sampling circuit can gather ambient temperature to output a voltage (or electric current) signal, during electric current or the voltage signal transmission that temperature sampling circuit exported compensated structure, compensate the sampling result of electric current sampling module, the utility model discloses a can adopt the segmentation compensation mode to solve the error and be the nonlinear relation with the temperature.
Drawings
FIG. 1 is a sectional compensation circuit structure of the present invention in which the current sampling error is nonlinear with respect to temperature;
fig. 2 is a scheme architecture for improving current sampling accuracy of the present invention;
fig. 3 the utility model discloses a linear superposition compensation circuit structure of current sampling error and temperature linear relation.
Detailed Description
The working principle of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.
The utility model provides a scheme that improves current sampling precision with analog circuit includes several parts of current sampling circuit, temperature sampling circuit, precision compensation structure.
Temperature sampling can be realized by NTC resistance and diode isothermal sensitive devices. Taking the NTC resistor as an example, a reference current (which does not change with temperature) flows through the NTC resistor, and the voltage across the resistor decreases with the increase of temperature, i.e., the linear reaction temperature value. This value can be input into the precision compensation structure, or the voltage can be converted into a voltage which increases with the temperature increase or a current which has a linear relation with the temperature through a certain conversion, addition and subtraction structure, as the case may be.
The current sampling circuit may be implemented with a sampling resistor or a hall element. The voltage (or current) signal reflecting the magnitude of the sampled current is affected by temperature and generates a certain error. May be higher or lower than the actual value.
Before designing the precision compensation structure, the current sampling structure needs to be tested to obtain a relation curve of sampling errors along with temperature changes. It is then determined from the curve how much voltage (or current) should be compensated into the measured signal at a certain temperature to get an actual accurate value. The simplest of these is that the error is linear with temperature. The case of linear errors and the case of non-linear errors are discussed below in two embodiments.
When the error between the output of the current sampling circuit and the actual value is linear, the relationship between the actual value and the sampling value can be expressed as:
Vout＝Vref+bVcs+cVT
vout is voltage which truly reflects the magnitude of sampled current, namely the output of the temperature compensation circuit, Vcs is the output of the current sampling circuit, the information reflected by the voltage contains certain error, VT is a voltage value which is in a linear relation with temperature, Vref is a direct-current voltage value to be compensated, and b and c are coefficients. According to this relation, the precision compensation structure can be designed such that two voltages are proportionally added by a voltage adder as shown in fig. 2. An accurate output value is obtained.
If the error curve is positively correlated with the temperature and the output of the temperature sampling module is positively correlated with the temperature, the circuit connected according to fig. 2 can obtain the result, but if the error curve is positively correlated with the temperature and the output of the temperature sampling module is negatively correlated with the temperature, the output of the temperature sampling module and the resistance connected with the output of the temperature sampling module are connected to the negative input end of the cloud amplifier for subtraction. Other cases are also analyzed. If the error and the temperature present the relationship of quadratic, differential, integral, etc., the operational amplifier can be used to build a specific operational circuit to realize the function.
Because the relation of the sampling error of a specific sampling circuit along with the change of the temperature is very complex, a specific function is difficult to fit, or the error after fitting is still not negligible, namely, a segmented compensation mode which has higher compensation precision, is relatively more flexible and can be more generally applied to various error compensation can be adopted.
In the scheme of sectional compensation, the compensation accuracy is closely related to the number of comparators, for convenience of understanding, taking four comparators in fig. 3 as an example, the output of the temperature sampling circuit is connected to the input end of each comparator, the other input end of the comparator is connected with the reference voltages V1, V2, V3 and V4 … … which are not connected, if the voltage output by the temperature sampling module is the voltage which is increased along with the temperature increase, V1, V2, V3 and V4 … … are sequentially increased according to a certain step size, and otherwise are sequentially decreased. The output of each comparator controls an NMOS tube to be used as a switch, and controls the switch of a reference current, wherein the reference current is the mirror image current of Iref. Taking the first route as an example: the source terminal of MP0 is connected to the power supply and the drain terminal and gate terminal are connected to Iref, forming a self-bias. The gate of the MP0 is connected with the gates of all the back PMOSs to form a current mirror, and the mirror ratio of the current mirror is set according to the step sizes of V1, V2, V3 and V4 … … and the errors of the temperature points represented by the step sizes. The source terminal of MP1 is connected with power voltage. The drain of MP1 is connected to the drain of MN 1. The source of MN1 is connected with the upper end of resistor R12, and the gate of MN1 is connected with the output of comparator COMP1 and is controlled by comparator COMP 1. In the first path, V1 is connected with the positive input end of COMP1, the temperature sampling circuit is connected with the negative input end of COMP1, if the output of the temperature sampling circuit is reduced to be lower than V1 due to temperature rise, the output of the comparator is high, MN1 is conducted, current on MP1 is injected into R12, and the voltage on R12 is increased. So that the value of the error compensation increases. The other circuits are connected according to the circuit, if the temperature rises to a certain value and the error is reduced, the compensated voltage should be reduced, so that the reference voltage corresponding to the temperature point of the temperature sampling circuit should be connected to the negative input end of the comparator, the output of the temperature sampling circuit is connected to the positive input end of the comparator, and when the temperature rises to the point, the current of the circuit is turned off, so that the voltage on the resistor R12 is reduced. The mirror current value of each path is set to the error voltage (set to VN) that should be increased (or decreased) with respect to the previous temperature point divided by R. If the mirror ratio of a certain cry to the reference current is 1: k, and the reference point of the way wants to have an error voltage VN with respect to the previous reference point, then:
I＝K*Iref＝VN/R12
the connection of the inputs of each comparator depends on whether the error compensation should be increased or decreased depending on the point at which the temperature reaches this point.
R12 is first fed with a reference current Iref1, i.e. a dc voltage is first compensated, the specific value is determined according to the error condition, then the current of all branches is fed through R12 to form a total error compensation voltage, which is fed to the positive input terminal of the operational amplifier a 2. The negative input of the operational amplifier a2 is connected to its output and to one end of R7, forming a unity gain negative feedback. The voltage on the R12 is not influenced by the subsequent stage circuit by clamping and isolation of the A2. The output of the current sampling circuit is connected to R8. The other ends of R7 and R8 and R9 are connected to the positive input end of the operational amplifier A1, and the other end of R9 is grounded. The negative input ends of the operational amplifier are connected with R10 and R11, the other end of R10 is grounded, and the other end of R11 is connected with the output of the operational amplifier and serves as the output of the whole system. R7, R8, R9, R10, R11, and an operational amplifier a1 constitute an addition operation circuit as in the previous embodiment, and the compensated error voltage is added to the output of the current sampling circuit to form a precise output.
In order to improve the compensation accuracy of the accuracy compensation structure, it is necessary to decrease the steps between V1, V2, and V3 … … while increasing the number of comparators. The specific situation is adjusted according to the application requirements.
It is to be understood that the invention is not limited to the precise arrangements and components shown above. Various modifications, changes and optimizations may be made to the order of the steps, details and operations of the above methods and structures without departing from the scope of the claims.
Claims (1)
1. The utility model provides a novel improve circuit structure that electric current adopted precision with analog circuit which characterized in that: the structure comprises a current sampling module, a temperature sampling module and a precision compensation structure; wherein, at least one comparator is connected with the temperature sampling module, the output end of the temperature sampling circuit is connected with the input end of each comparator, and the other input end of the comparator is connected with the reference voltages V1, V2, V3 and V4 … … which are not connected; the output of each comparator controls an NMOS tube as a switch to control the switch of a reference current from IrefThe mirror current of (1); the source end of the MP1 is connected with power voltage, the drain electrode of the MP1 is connected with the drain electrode of the MN1, the source electrode of the MN1 is connected with the upper end of a resistor R12, and the grid electrode of the MN1 is connected with the output of a comparator COMP1 and is controlled by a comparator COMP 1; v1 in the first path is connected with the positive input end of COMP1, the temperature sampling circuit is connected with the negative input end of COMP1, the output of the current sampling circuit is connected to R8, the other ends of R7 and R8 and R9 are connected with the authentication input end of an operational amplifier A1, the other end of R9 is grounded, the negative input end of the operational amplifier is connected with R10 and R11, the other end of R10 is grounded, and the other end of R11 is connected with the output of the operational amplifier and serves as the output of the whole system; the R7, the R8, the R9, the R10, the R11 and the operational amplifier A1 form an addition operation circuit, and the compensated error voltage is added to the output of the current sampling circuit to form accurate output;
the addition operation circuit is characterized in that R7, R8 and R9 are connected to the positive input end of the operational amplifier, the other end of R7 is connected with the output of the temperature sampling circuit, the other end of R8 is connected with the output of the current sampling circuit, the other end of R9 is grounded, R10 and R11 are connected with the negative input end of the operational amplifier, the other end of R10 is grounded, and the other end of R11 is connected with the output end of the operational amplifier; thus, a voltage adder is constructed.
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| CN201921190280.1U CN210377199U (en) | 2019-07-29 | 2019-07-29 | Novel circuit structure for improving current adoption precision by using analog circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113867470A (en) * | 2021-10-29 | 2021-12-31 | 西安微电子技术研究所 | Temperature compensation type constant current source unit and current frequency conversion circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113867470A (en) * | 2021-10-29 | 2021-12-31 | 西安微电子技术研究所 | Temperature compensation type constant current source unit and current frequency conversion circuit |
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