CN218470841U - High-side current source sensing circuit - Google Patents
High-side current source sensing circuit Download PDFInfo
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- CN218470841U CN218470841U CN202221785207.0U CN202221785207U CN218470841U CN 218470841 U CN218470841 U CN 218470841U CN 202221785207 U CN202221785207 U CN 202221785207U CN 218470841 U CN218470841 U CN 218470841U
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Abstract
A high side current source sensing circuit, comprising: the power electronic switch tube, power supply Vb, high-side power supply Vh, current sampler and signal amplifier; the power electronic switching tube is used for driving a load; the power supply supplies power supply energy to the power electronic switching tube; the current sampler is connected in series between a power supply Vb and a power supply end of a power electronic switching tube, the high-side power supply Vh is higher than the power supply Vb and meets the requirement of a working power supply of the signal amplifier, a power supply negative power supply Vb and a power supply positive power supply Vh of the signal amplifier are respectively added to the input end of the signal amplifier, and the output of the signal amplifier is a current output sensing signal Vo of the high-side current source sensing circuit. The utility model discloses the sensing is accurate, the reliable operation.
Description
Technical Field
The utility model belongs to the electronic control field especially relates to a high limit electric current source sensing circuit.
Background
Referring to fig. 4, a patent application 202110130329.X discloses a high-side current collecting and safety protection circuit of a power electronic switch tube, and discloses that a power electronic switch tube 1 is an electronic switch MOS tube, an input end of which is connected with a power supply Vb, an output end of which is connected with a load L, and a low end (drain electrode D) of the MOS tube is connected with an input end of a signal amplifier 3.
By adopting the control mode, on one hand, the current sampler of the high-side driven power electronic switch tube is the internal resistance Ron of the electronic switch MOS tube, but when the MOS tube works, the Ron is greatly changed along with the temperature, thereby influencing the accuracy of the conduction current.
On the other hand, in order to prevent the negative terminal S of the power supply of the MOS transistor in the off state from having too low voltage relative to the negative terminal of the operational amplifier, which may result in the destruction of the operational amplifier, a clamping diode 4 is usually used for protecting the negative terminal of the operational amplifier.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a receive temperature to influence less, and reliable high limit current source sensing circuit.
In order to achieve the above purpose, the utility model adopts the following specific technical scheme:
a high side current source sensing circuit, comprising: the power electronic switch tube, power supply Vb, high-side power supply Vh, current sampler and signal amplifier; the power electronic switching tube is used for driving a load; the power supply supplies power supply energy to the power electronic switching tube; the current sampler is connected in series between a power supply Vb and a power supply end of the power electronic switching tube, the high-side power supply Vh is higher than the power supply Vb and meets the requirement of a working power supply of the signal amplifier, a power supply negative power supply of the signal amplifier is Vb, a power supply positive power supply of the signal amplifier is Vh, a differential pressure signal at two ends of the current sampler is used as an input signal of the signal amplifier, and the output of the signal amplifier is a current output sensing signal Vo of the high-side current source sensing circuit.
Further, the current sampler is a resistor.
Furthermore, the current sampler is a constantan wire.
Furthermore, the current sampler is a resistor generated by printing copper wires on the PCB.
Further, the signal amplifier is an operational amplifier.
Further, the negative end of the current source of the current sampler is connected to the negative input end of the operational amplifier, so that the reverse amplification mode of the operational amplifier is formed.
Further, the current sampler is characterized in that a positive bias circuit is arranged at the negative terminal, so that the voltage applied to the input positive terminal of the operational amplifier is a positive voltage signal relative to the power supply negative power supply Vb of the operational amplifier, and a homodromous amplification mode of the operational amplifier is formed.
Further, the positive bias circuit is composed of a high-side power supply Vh connecting resistor R9, a negative terminal connecting resistor R8 of the current sampler, and R8 and R9 are positive with respect to the voltage Vb at the connection point.
Furthermore, the high-side power supply Vh meets the requirement of a conduction driving level of a driving power electronic switch tube.
The utility model discloses an have following advantage:
1) A current sampler is arranged at the power input end of the power electronic switching tube, and a resistance device with small resistance value change along with temperature, such as constantan wire and a low-temperature coefficient resistor, is selected, so that the sensing current is more accurate.
2) Signals at two ends of the current sampler are added to the input end of the signal amplifier, and the voltage formed by the sampled current signals is the reference ground voltage Vb relative to the amplifier and has a small voltage value, so that the amplifier is safe to work, the common-mode voltage of the input end is small, and the amplification linearity is good.
Drawings
FIG. 1 is a schematic diagram of an embodiment of the present invention;
FIG. 2 is a schematic diagram of a second embodiment of the present invention;
FIG. 3 is a diagram showing the relationship between changes of Vh, vb and Vo;
fig. 4 is a schematic diagram of the prior art of the present invention.
Detailed Description
In order to better understand the structure and the principle of the present invention, the following description is made in conjunction with the accompanying drawings.
As shown in fig. 1, the high-side current source sensing circuit of the present invention includes a power electronic switch tube 1, a power supply Vb, a high-side power supply Vh, a current sampler 2 and an amplifier 3; the power electronic switching tube 1 is used for driving a load L; the power supply Vb provides power supply energy for the power electronic switching tube; the current sampler 2 comprises a common resistor (a patch or a contact pin, a carbon film or a metal film), a constantan wire resistor and a resistor generated by printing a copper covered wire on a PCB (printed circuit board), and the current sampler 2 is connected in series between a power supply Vb and a power end of the power electronic switch tube 1; the power supply negative power supply of the signal amplifier is Vb, and the power supply positive power supply of the signal amplifier is Vh; the signal voltage at the two ends of the current sampler 2 is added to the input end of the signal amplifier 3, and the output voltage Vo amplified by the signal amplifier 3 is the sensing voltage of the high-side current source.
The high-side power supply Vh is connected to the driving end of the power electronic switch tube 1 and meets the requirement of driving the power electronic switch tube 1 to be completely conducted.
The application of the output sensing voltage Vo is described in detail in the prior patent application, and includes providing protection for the electronic switch tube 1 with a single chip microcomputer as a core or providing protection for the electronic switch 1 which is only composed of an analog circuit.
Example one
As shown in FIG. 1, one end of a sampling resistor R3 indicated by a current sampler 2 is connected with a power supply Vb, the other end of the sampling resistor R3 is connected with the D end of an MOS (metal oxide semiconductor) tube indicated by a power electronic switching tube 1, a differential pressure signal at two ends of the resistor R3 is connected to the input end of an inverting operational amplifier through resistors R4 and R5, and the amplification factor is-R6/R4.
When the VP input is a high-resistance signal (a disconnection signal), vh is added to the input resistor R2 end of the MOS tube through R1, so that the MOS tube is completely conducted to work; because both the on-resistance of the R3 and the on-resistance of the MOS transistor are small, the current flowing through R3 can be approximated to Vb/Rl (assuming that the dc resistance responsible for L is Rl), and the output voltage Vo of the current sensor is:
Vo=（R6/R4）*R3*（Vb/Rl）
when Vp is a low level (GND, ground) signal, the MOS transistor is turned off, and the current flowing through R3 is zero, the output voltage Vo of the current sensor is:
Vo=（R6/R4）*R3*0
example two
As shown in fig. 2, one end of R3 indicated by the current sampler 2 is connected to the power supply Vb, the other end is connected to the D end of the MOS transistor disposed in the power electronic switching transistor 1, the D end is further connected to a resistor R8, the other end of the resistor R8 is connected to a resistor R4, and the other end of the resistor R4 is connected to the input positive terminal of the operational amplifier; the connection point of the resistors R4 and R8 is connected to a high-side power supply Vh through a resistor R9; r9 and R8 are selected such that the potential at the junction of the resistors R8 and R4 is positive with respect to Vb. The positive bias voltage signal of the connection point of R8 and R9 is connected to the input end of the same-direction operational amplifier through resistors R4 and R5, and the amplification factor of the same-direction operational amplifier is (1 + R6/R4).
The output end of the operational amplifier is connected with the resistor R7 and then outputs a current sensing signal Vo of the high-side current source sensing circuit.
As fig. 3, the utility model discloses well high side power Vh is higher than power supply Vb all the time, and the difference equals between the two moreover, and the electric current sensing signal Vo of output is higher than power supply Vb, and signal Vo changes along with power supply Vb's change moreover.
It is to be understood that the present invention has been described with reference to certain embodiments and that various changes or equivalents may be substituted for elements thereof without departing from the spirit and scope of the invention as defined by the appended claims. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the present application are intended to be covered by the present invention.
Claims (9)
1. A high side current source sensing circuit, comprising:
the device comprises a power electronic switch tube (1), a power supply Vb, a high-side power supply Vh, a current sampler (2) and a signal amplifier (3);
the power electronic switching tube is used for driving a load; the power supply supplies power supply energy to the power electronic switching tube;
the current sampler (2) is connected in series between a power supply Vb and a power supply end of the power electronic switching tube (1), the high-side power supply Vh is higher than the power supply Vb and meets the requirement of a working power supply of the signal amplifier (3), a power supply negative power supply of the signal amplifier is Vb, a power supply positive power supply of the signal amplifier is Vh, a differential pressure signal at two ends of the current sampler (2) is used as an input signal of the signal amplifier (3), and the output of the signal amplifier (3) is a current output sensing signal Vo of the high-side current source sensing circuit.
2. A high side current source sensing circuit according to claim 1, wherein the current sampler (2) is a resistor.
3. A high side current source sensing circuit according to claim 2, wherein said current sampler (2) is constantan wire.
4. A high side current source sensing circuit according to claim 2, wherein the current sampler (2) is a resistor formed by copper traces printed on a PCB.
5. A high side current source sensing circuit according to claim 1, wherein the signal amplifier (3) is an operational amplifier.
6. A high side current source sensing circuit according to claim 2, 3 or 4, characterized in that the negative current source terminal of the current sampler (2) is connected to the negative input terminal of the operational amplifier, constituting the inverting amplification mode of the operational amplifier.
7. A high side current source sensing circuit according to claim 2, 3 or 4, characterised in that the current sampler (2) is provided with a positive bias circuit at the negative terminal such that the voltage applied to the positive input terminal of the operational amplifier is a positive voltage signal with respect to the negative supply Vb of the operational amplifier, constituting a co-directional amplification mode of the operational amplifier.
8. A high-side current source sensing circuit according to claim 7, wherein the positive bias circuit is a high-side power supply Vh connecting resistor R9, a negative terminal connecting resistor R8 of the current sampler (2), R8 and R9 being such that at their junction point they are positive with respect to the voltage Vb.
9. A high side current source sensing circuit according to claim 1, wherein the high side power supply Vh connection meets the turn-on drive level requirement for driving the power electronic switching tube (1).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202221785207.0U CN218470841U (en) | 2022-07-11 | 2022-07-11 | High-side current source sensing circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202221785207.0U CN218470841U (en) | 2022-07-11 | 2022-07-11 | High-side current source sensing circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN218470841U true CN218470841U (en) | 2023-02-10 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202221785207.0U Active CN218470841U (en) | 2022-07-11 | 2022-07-11 | High-side current source sensing circuit |
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| Country | Link |
|---|---|
| CN (1) | CN218470841U (en) |
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2022
- 2022-07-11 CN CN202221785207.0U patent/CN218470841U/en active Active
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