Sampling circuit and sampling device

Abstract

The present application discloses a sampling circuit and a sampling device. The sampling circuit of the present application is used to sample a circuit to be detected to obtain a sampling voltage. The sampling circuit includes: a current mutual inductance circuit, a first operational amplifier circuit, and a second operational amplifier circuit, wherein the current mutual inductance circuit is used to provide an induced voltage, the first input end of the first operational amplifier circuit is connected to the first end of the current mutual inductance circuit, and the second input end of the first operational amplifier circuit is connected to the second end of the current mutual inductance circuit; the first input end of the second operational amplifier circuit is connected to the output end of the first operational amplifier circuit and the second input end of the first operational amplifier circuit, and the second input end of the second operational amplifier circuit is connected to the second end of the current mutual inductance circuit; when the induced voltage is a negative voltage, the first operational amplifier circuit and the second operational amplifier circuit are used to convert the induced voltage into a positive voltage to obtain a sampling voltage. The sampling circuit of the present application has a simple design structure, low cost, and high sampling accuracy.

Description

Technical Field

[0001] The present application relates to the field of integrated circuit design, and in particular to a sampling circuit and a sampling device. Background Art

[0002] In the field of new energy power electronics, topologies such as inverter circuits and bidirectional DC / DC circuits have bidirectional currents, and the output current values ​​can be positive or negative. Since the control chip needs to detect the main power current of the above circuit topologies for calculation and protection, a current sampling circuit is required to transmit the main power current value to the control chip.

[0003] In the prior art, full-wave rectification is generally used to convert positive and negative voltages into positive voltages. There is a voltage drop in the diode in the circuit, so the voltage value of the sampled signal will be lower than the actual voltage value, and there will be distortion at the zero crossing. The signal error of the existing sampling circuit is large. Utility Model Content

[0004] The present application provides a sampling circuit and a sampling device to solve the technical problem of large signal error in the sampling circuit in the prior art.

[0005] In order to solve the above technical problems, the present application provides a sampling circuit, which includes: a current mutual induction circuit, a first operational amplifier circuit and a second operational amplifier circuit, wherein the current mutual induction circuit is used to provide an induced voltage; the first input end of the first operational amplifier circuit is connected to the first end of the current mutual induction circuit, and the second input end of the first operational amplifier circuit is connected to the second end of the current mutual induction circuit; the first input end of the second operational amplifier circuit is connected to the output end of the first operational amplifier circuit and the second input end of the first operational amplifier circuit, and the second input end of the second operational amplifier circuit is connected to the second end of the current mutual induction circuit; when the induced voltage is a negative voltage, the first operational amplifier circuit and the second operational amplifier circuit are used to convert the induced voltage into a positive voltage to obtain a sampling voltage.

[0006] Further, in the case where the induced voltage is a forward voltage, the first operational amplifier circuit is in a following state, and the output voltage of the output terminal of the second operational amplifier circuit is the induced voltage.

[0007] Furthermore, the first operational amplifier circuit includes a first resistor, a second resistor, a first operational amplifier, a third resistor and a diode; the first input terminal of the first operational amplifier is connected to the second end of the current mutual inductance circuit through the first resistor, the second input terminal of the first operational amplifier is connected to the first end of the current mutual inductance circuit through the second resistor, and the output terminal of the first operational amplifier is connected to the positive electrode of the diode through the third resistor.

[0008] Furthermore, the second operational amplifier circuit includes a fourth resistor, a fifth resistor and a second operational amplifier; the first input terminal of the second operational amplifier is connected to the second end of the current mutual inductance circuit through the fourth resistor, one end of the fifth resistor is connected to the first input terminal of the second operational amplifier, the other end of the fifth resistor is connected to the output terminal of the second operational amplifier, and the second input terminal of the second operational amplifier is respectively connected to the cathode of the diode and the first input terminal of the first operational amplifier.

[0009] Furthermore, the current transformer circuit includes a current transformer and a sixth resistor, the first output end of the current transformer serves as the first end of the current transformer circuit, the second output end of the current transformer serves as the second end of the current transformer circuit, and the second output end of the current transformer is grounded through the sixth resistor.

[0010] Further, when the induced voltage is a forward voltage, the first input terminal of the first op amp receives the induced voltage, the voltage of the first input terminal of the first op amp is greater than the voltage of the second input terminal of the first op amp, the output terminal of the first op amp outputs a low level, and the diode is reverse cut off; the second input terminal of the second op amp receives the induced voltage, the voltage of the first input terminal of the second op amp is equal to the voltage of the second input terminal of the second op amp, and the output voltage of the output terminal of the second op amp is equal to the induced voltage.

[0011] Further, when the induced voltage is a negative voltage, the voltage at the first input terminal of the first op amp is less than the voltage at the second input terminal of the first op amp, the output terminal of the first op amp outputs a high level, and the diode is turned on.

[0012] Furthermore, the output voltage at the output terminal of the second operational amplifier satisfies the following formula:

[0013]

[0014] Among them, V s is the output voltage of the output terminal of the second op amp, V 02 is the induced voltage, R5 is the resistance value of the fifth resistor, and R4 is the resistance value of the fourth resistor.

[0015] In order to solve the above technical problems, the present application also provides a sampling device, which includes the sampling circuit of any of the above embodiments.

[0016] Furthermore, the sampling device includes a control circuit connected to the output end of the second operational amplifier circuit to collect an output voltage of the output end of the second operational amplifier circuit and calculate the induced voltage based on the output voltage of the output end of the second operational amplifier circuit.

[0017] The beneficial effects of the present application are as follows: Different from the prior art, the sampling circuit of the present application is used to sample the circuit to be detected to obtain a sampling voltage, and the sampling circuit includes: a current mutual inductance circuit, a first operational amplifier circuit, and a second operational amplifier circuit, wherein the current mutual inductance circuit is used to provide an induced voltage, the first input end of the first operational amplifier circuit is connected to the first end of the current mutual inductance circuit, and the second input end of the first operational amplifier circuit is connected to the second end of the current mutual inductance circuit; the first input end of the second operational amplifier circuit is connected to the output end of the first operational amplifier circuit and the second input end of the first operational amplifier circuit, and the second input end of the second operational amplifier circuit is connected to the second end of the current mutual inductance circuit; when the induced voltage is a negative voltage, the first operational amplifier circuit and the second operational amplifier circuit are used to convert the induced voltage into a positive voltage, thereby obtaining a sampling voltage. The sampling circuit of the present application has a simple design structure and low cost, and can effectively solve the problems of inaccurate sampling voltage value and zero-crossing distortion caused by diodes in the existing solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] in:

[0020] Figure 1 is a structural schematic diagram of an embodiment of a sampling circuit provided by the present application;

[0021] Figure 2 It is a schematic diagram of a framework of an embodiment of a sampling device provided by the present application. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0023] The present application provides a sampling circuit, which is used to sample a circuit to be detected to obtain a sampling voltage. The sampling circuit has a simple structure, low cost, and a small error in the obtained sampling voltage, which can effectively solve the problems of inaccurate sampling voltage and zero-crossing distortion caused by diodes in the existing solution. The sampling circuit can replace a dedicated sampling chip, which has a low cost. Through the sampling circuit, the design complexity and high cost of the bidirectional power supply used by the operational amplifier in the existing solution can be solved. The design structure of the sampling circuit of the present application is simple and reliable, and the cost advantage is obvious.

[0024] See also Figure 1 As shown, Figure 1 1 is a schematic diagram of the structure of an embodiment of a sampling circuit provided by the present application. Specifically, the sampling circuit 10 includes a current mutual inductance circuit 11, a first operational amplifier circuit 12 and a second operational amplifier circuit 13.

[0025] Among them, the current mutual induction circuit 11 is used to provide an induced voltage, the first input end of the first operational amplifier circuit 12 is connected to the first end of the current mutual induction circuit 11, the second input end of the first operational amplifier circuit 12 is connected to the second end of the current mutual induction circuit 11, the first input end of the second operational amplifier circuit 13 is connected to the output end of the first operational amplifier circuit 12 and the second input end of the first operational amplifier circuit 12, and the second input end of the second operational amplifier circuit 13 is connected to the second end of the current mutual induction circuit 11.

[0026] When the induced voltage is a negative voltage, the first operational amplifier circuit 12 and the second operational amplifier circuit 13 are used to convert the induced voltage into a positive voltage, so that the sampling circuit 10 completes sampling, thereby obtaining a sampled voltage, wherein the sampled voltage is the voltage output by the output end of the second operational amplifier circuit 13. The sampling circuit 10 of the present application has a simple structure, low cost, and can obtain the sampled voltage more accurately.

[0027] Furthermore, when the induced voltage is a forward voltage, the first operational amplifier circuit 12 is in a follow state, and the output voltage of the output end of the second operational amplifier circuit 13 is the induced voltage. The method for obtaining the induced voltage is simple and has high accuracy.

[0028] Furthermore, if Figure 1As shown, the first operational amplifier circuit 12 includes a first resistor 121, a second resistor 122, a first operational amplifier 123, a third resistor 124 and a diode 125. The first input end of the first operational amplifier 123 is connected to the second end of the current mutual inductance circuit 11 through the first resistor 121, the second input end of the first operational amplifier 123 is connected to the first end of the current mutual inductance circuit through the second resistor 122, and the output end of the first operational amplifier 123 is connected to the positive electrode of the diode 125 through the third resistor 124. The first operational amplifier circuit 12 only uses common components such as resistors, small signal switching diodes and operational amplifiers in the industry, and has a simple design and obvious cost advantages.

[0029] Further, the second operational amplifier circuit 13 includes a fourth resistor 131, a fifth resistor 132, and a second operational amplifier 133. The first input terminal of the second operational amplifier 133 is connected to the second end of the current mutual inductance circuit 11 through the fourth resistor 131, one end of the fifth resistor 132 is connected to the first input terminal of the second operational amplifier 133, the other end of the fifth resistor 132 is connected to the output terminal of the second operational amplifier 133, and the second input terminal of the second operational amplifier 133 is respectively connected to the cathode of the diode 125 and the first input terminal of the first operational amplifier 123. The second operational amplifier circuit 13 only uses common components such as resistors and operational amplifiers in the industry, and has a simple design and low cost.

[0030] The current transformer circuit 11 includes a current transformer 111 and a sixth resistor 112. The first output end of the current transformer 111 serves as the first end of the current transformer circuit 11. The second output end of the current transformer 111 serves as the second end of the current transformer circuit 11. The second output end of the current transformer 111 is grounded through the sixth resistor 112. The current transformer 111 is used to scale the main power current in equal proportion. The sixth resistor 112 is used to convert the sampled current signal into a voltage signal.

[0031] In the sampling circuit 10 of the present application, when the main power current is positive, that is, when the induced voltage is a positive voltage, a positive voltage V is generated on the sixth resistor 112 through the current transformer 111. o1 The first input terminal of the first operational amplifier 123 is connected to the forward voltage V of the sixth resistor 112 through the first resistor 121. o1 The second input terminal of the first amplifier 123 is connected to the ground through the second resistor 122. Therefore, when the voltage V generated on the sixth resistor 112 o1 When V is positive, the voltage at the first input terminal of the first op amp 123 is greater than the voltage at the second input terminal (that is, the voltage at the inverting input terminal of the first op amp 123 is greater than the voltage at the non-inverting input terminal), the output terminal of the first op amp 123 outputs a low level, and the diode 125 is reversely cut off. Therefore, the first op amp 123 and its peripheral circuits cannot form an inverting amplifier circuit, and the voltage at the first input terminal of the first op amp 123 is equal to Vo1 voltage, the voltage at the second input terminal of the second op amp 133 is also equal to V o1 According to the principle of virtual short and virtual break, the voltage at the first input terminal (inverting input terminal) of the second op amp 133 is equal to the voltage at the second input terminal (non-inverting input terminal) of the first op amp 123, that is, it is also equal to V o1 The voltage Vs at the output end of the second amplifier 133 is equal to the induced voltage V o1 .

[0032] When the main power current is negative, that is, when the induced voltage is a negative voltage, a negative voltage V is generated on the sixth resistor 112 through the current transformer 111. o2 , the voltage of the first input terminal (reverse input terminal) of the first amplifier 123 is less than the voltage of the second input terminal (non-inverting input terminal) of the first amplifier 123, the output terminal of the first amplifier 123 outputs a high level, and the diode 125 is turned on. Therefore, the first amplifier 123 can form an inverting amplifier circuit through the first resistor 121, the third resistor 124 and the diode 125. According to the principle of virtual short and virtual break, the voltage of the first input terminal of the first amplifier 123 is equal to the voltage of the second input terminal. Since the second input terminal of the first amplifier 123 is grounded through the second resistor 122, the voltage of the first input terminal and the second input terminal of the first amplifier 123 are both 0V, and the voltage of the second input terminal of the second amplifier 133 is also 0V. Similarly, according to the principle of virtual short and virtual break, the voltage of the first input terminal of the first amplifier 123 is also 0V, then the voltage Vs of the output terminal of the second amplifier 133 satisfies the following formula:

[0033]

[0034] Among them, V s is the output voltage of the output terminal of the second operational amplifier 133, V 02 is the induced voltage, R5 is the resistance value of the fifth resistor 132 , and R4 is the resistance value of the fourth resistor 131 .

[0035] The fourth resistor 131 and the fifth resistor 132 are used to adjust the proportional gain of the second amplifier 133. For example, when the resistance value R4 of the fourth resistor 131 is designed to be equal to the resistance value R5 of the fifth resistor 132, that is, the Vs voltage is equal to the negative V o2 voltage, thereby achieving the negative voltage V o2 Converted into positive voltage and transmitted to the control chip for sampling.

[0036] In the above sampling circuit 10, the first resistor 121 and the second resistor 122 are used to offset the output offset voltage caused by the bias current at the input end of the first op amp 123. The third resistor 124 is used to limit the current flowing through the diode 125 when the first op amp 123 outputs a high level. In the above sampling circuit 10, the first op amp 123 is used for amplification and following, and the second op amp 133 is used for proportional amplification. The diode 125 is used to change the working mode of the first op amp 123. When the induced voltage is a forward voltage, the reverse cutoff of the diode 125 makes the first op amp 123 work in the following state; when the induced voltage is a negative voltage, the forward conduction of the diode 125 makes the first op amp 123 work in the amplification state.

[0037] In the sampling circuit 10 of the present application, when the induced voltage is a negative voltage, the first operational amplifier circuit 12 and the second operational amplifier circuit 13 are used to convert the induced voltage into a positive voltage. When the induced voltage is a positive voltage, the first operational amplifier 123 works in a follow-up state, and the voltage value at the output end of the second operational amplifier 133 is equal to the induced voltage. The sampling circuit 10 of the present application has a simple structure, and the sampling voltage can be obtained without using a sampling chip. The circuit structure of the present application only uses industry-common resistors, small-signal switching diodes, operational amplifiers and other components, and the design is simple and reliable, and the cost is low. Moreover, the sampling voltage obtained by the sampling circuit 10 of the present application has a high accuracy, which can effectively solve the problems of inaccurate sampling voltage values ​​and zero-crossing distortion caused by the diodes of the sampling circuit in the prior art.

[0038] This application also provides a sampling device, see Figure 2 As shown, Figure 2 1 is a schematic diagram of a framework of an embodiment of a sampling device provided by the present application. Specifically, the sampling device 20 includes a sampling circuit 10. The sampling circuit 10 is the sampling circuit 10 of any of the above embodiments. For the specific structure of the sampling circuit 10, please refer to the introduction of any of the above embodiments, which will not be repeated here.

[0039] Furthermore, the sampling device 20 may further include a control circuit 21, which is connected to the output end of the second operational amplifier circuit 13 in the sampling circuit 10 to collect the output voltage of the output end of the second operational amplifier circuit 13, and calculate the induced voltage based on the output voltage of the output end of the second operational amplifier circuit 13. The structure of the control circuit 21 is within the scope that can be understood by those skilled in the art and will not be described in detail herein.

[0040] The above description is only an implementation method of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A sampling circuit, characterized in that: Used to sample the circuit to be detected to obtain a sampled voltage, the sampling circuit comprising: A current mutual induction circuit for providing an induced voltage; a first operational amplifier circuit, wherein a first input end of the first operational amplifier circuit is connected to a first end of the current mutual induction circuit, and a second input end of the first operational amplifier circuit is connected to a second end of the current mutual induction circuit; a second operational amplifier circuit, wherein a first input end of the second operational amplifier circuit is connected to an output end of the first operational amplifier circuit and a second input end of the first operational amplifier circuit, and a second input end of the second operational amplifier circuit is connected to a second end of the current mutual inductance circuit; In the case where the induced voltage is a negative voltage, the first operational amplifier circuit and the second operational amplifier circuit are used to convert the induced voltage into a positive voltage to obtain the sampling voltage.

2. The sampling circuit according to claim 1, characterized in that: When the induced voltage is a forward voltage, the first operational amplifier circuit is in a follow-up state, and the output voltage of the output terminal of the second operational amplifier circuit is the induced voltage.

3. The sampling circuit according to claim 2, characterized in that: The first operational amplifier circuit includes a first resistor, a second resistor, a first operational amplifier, a third resistor and a diode; the first input end of the first operational amplifier is connected to the second end of the current mutual inductance circuit through the first resistor, the second input end of the first operational amplifier is connected to the first end of the current mutual inductance circuit through the second resistor, and the output end of the first operational amplifier is connected to the positive electrode of the diode through the third resistor.

4. The sampling circuit according to claim 3, characterized in that: The second operational amplifier circuit includes a fourth resistor, a fifth resistor and a second operational amplifier; the first input terminal of the second operational amplifier is connected to the second end of the current mutual inductance circuit through the fourth resistor, one end of the fifth resistor is connected to the first input terminal of the second operational amplifier, the other end of the fifth resistor is connected to the output terminal of the second operational amplifier, and the second input terminal of the second operational amplifier is respectively connected to the cathode of the diode and the first input terminal of the first operational amplifier.

5. The sampling circuit according to claim 4, characterized in that: The current transformer circuit includes a current transformer and a sixth resistor, the first output end of the current transformer serves as the first end of the current transformer circuit, the second output end of the current transformer serves as the second end of the current transformer circuit, and the second output end of the current transformer is grounded through the sixth resistor.

6. The sampling circuit according to claim 4, characterized in that: When the induced voltage is a forward voltage, the first input terminal of the first op amp receives the induced voltage, the voltage of the first input terminal of the first op amp is greater than the voltage of the second input terminal of the first op amp, the output terminal of the first op amp outputs a low level, and the diode is reversely cut off; The second input terminal of the second op amp receives the induced voltage, the voltage of the first input terminal of the second op amp is equal to the voltage of the second input terminal of the second op amp, and the output voltage of the output terminal of the second op amp is equal to the induced voltage.

7. The sampling circuit according to claim 4, characterized in that: When the induced voltage is a negative voltage, the voltage at the first input terminal of the first op amp is less than the voltage at the second input terminal of the first op amp, the output terminal of the first op amp outputs a high level, and the diode is turned on.

8. The sampling circuit according to claim 7, characterized in that: The output voltage at the output terminal of the second op amp satisfies the following formula: Among them, the V s is the output voltage of the output terminal of the second op amp, the V 02 is the induced voltage, R5 is the resistance value of the fifth resistor, and R4 is the resistance value of the fourth resistor.

9. A sampling device, characterized in that: The sampling device comprises the sampling circuit according to any one of claims 1-8.

10. The sampling device according to claim 9, characterized in that The sampling device comprises a control circuit, The control circuit is connected to the output end of the second operational amplifier circuit to collect the output voltage of the output end of the second operational amplifier circuit, and calculate the induced voltage based on the output voltage of the output end of the second operational amplifier circuit.

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