A non-isolated high-side current sampling circuit and DC power supply

Abstract

The present invention relates to a non-isolated high-side current sampling circuit and a DC power supply. In the non-isolated high-side current sampling circuit, the first end of a high-side sampling resistor R1 is connected to a DC bus of a DC power supply, and the second end of the high-side sampling resistor R1 is connected to the emitter of a transistor Q; the high-side sampling resistor R1 is connected to the input end of a primary amplifier circuit, the sampling voltage of the high-side sampling resistor R1 is input to the primary amplifier circuit, the output end of the primary amplifier circuit is connected to the input end of a secondary modulation circuit, and the output end of the secondary modulation circuit is connected to the base of the transistor Q; the collector of the transistor Q is connected to the first end of a low-side sampling resistor R11, and the second end of the low-side sampling resistor R11 is connected to the negative electrode of the DC power supply. The present invention solves the problem that the amplifier cannot withstand a higher common mode voltage when directly sampling in the prior art, and can be used in DC bus protection with a voltage of 24V to 100V, thereby effectively improving the reliability of the DC power supply.

Description

Technical Field

[0001] The present invention relates to the field of direct current sampling, and more specifically to a non-isolated high-side current sampling circuit and a direct current power supply. Background Art

[0002] The current current detection methods are mainly divided into electromagnetic detection and resistance detection (including high-side detection and low-side resistance). Electromagnetic detection generally uses Hall elements to achieve non-contact detection, which has high safety, high cost and medium accuracy. Resistance detection achieves sampling by connecting a sampling resistor in series in the circuit, with a direct electrical connection, medium safety, low cost and high accuracy. High-side detection has a greater performance advantage than low-side detection, which can eliminate ground interference and prevent the busbar from short-circuiting to the ground. However, the common-mode withstand voltage of general-purpose op amps is generally within 20V, and it cannot directly detect power supplies above 24V. A detection circuit that can adapt to high common-mode voltage is required. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a non-isolated high-side current sampling circuit and a DC power supply in view of the above-mentioned defects of the prior art.

[0004] The technical solution adopted by the present invention to solve the technical problem is: constructing a non-isolated high-side current sampling circuit, including a high-side sampling resistor R1, a voltage-regulating tube voltage-dividing circuit, a first-level amplification circuit, a second-level modulation circuit, a transistor Q, and a low-side sampling resistor R11;

[0005] The first end of the high-side sampling resistor R1 is connected to the DC bus of the DC power supply, the second end of the high-side sampling resistor R1 is connected to the emitter of the transistor Q, and the second end of the high-side sampling resistor R1 is connected to the load; the high-side sampling resistor R1 is connected to the input end of the first-level amplifier circuit, the sampling voltage of the high-side sampling resistor R1 is input into the first-level amplifier circuit, the output end of the first-level amplifier circuit is connected to the input end of the second-level modulation circuit, and the output end of the second-level modulation circuit is connected to the base of the transistor Q; the collector of the transistor Q is connected to the first end of the low-side sampling resistor R11, the second end of the low-side sampling resistor R11 is connected to the negative electrode of the DC power supply, and the negative electrode of the DC power supply is grounded.

[0006] Furthermore, the non-isolated high-side current sampling circuit of the present invention further includes an output amplifier circuit connected to the low-side sampling resistor R11 , and the output amplifier circuit is used to amplify the voltage across the low-side sampling resistor R11 .

[0007] Further, in the non-isolated high-side current sampling circuit of the present invention, the output amplifier circuit includes a third operational amplifier OP3, a resistor R12, a resistor R13, a resistor R14, a resistor R15, and a capacitor C2;

[0008] The inverting input terminal of the third operational amplifier OP3 is connected to the first end of the resistor R12, the second end of the resistor R12 is connected to the first end of the low-side sampling resistor R11, the second end of the resistor R12 is grounded through the capacitor C2, and the inverting input terminal of the third operational amplifier OP3 is connected to the output terminal of the third operational amplifier OP3 through the resistor R13; the non-inverting input terminal of the third operational amplifier OP3 is connected to the power supply voltage VCC through the resistor R14, and the non-inverting input terminal of the third operational amplifier OP3 is grounded through the resistor R15.

[0009] Further, in the non-isolated high-side current sampling circuit of the present invention, the voltage-regulating diode voltage-dividing circuit includes a voltage-regulating diode Z and a resistor R7;

[0010] The cathode of the voltage zener diode Z is connected to the DC bus, and the anode of the voltage zener diode Z is connected to the cathode of the DC power supply through the resistor R7; the cathode of the voltage zener diode Z serves as the anode power supply of the primary amplifier circuit and the secondary modulation circuit, and the anode of the voltage zener diode Z serves as the floating ground terminal of the primary amplifier circuit and the secondary modulation circuit.

[0011] Further, in the non-isolated high-side current sampling circuit of the present invention, the first-stage amplification circuit includes a first operational amplifier OP1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, and a capacitor C1;

[0012] The non-inverting input terminal of the first operational amplifier OP1 is connected to the first end of the resistor R1 through the resistor R2, and the non-inverting input terminal of the first operational amplifier OP1 is connected to the anode of the voltage-stabilizing diode Z through the resistor R5; the inverting input terminal of the first operational amplifier OP1 is connected to the second end of the resistor R1 through the resistor R3, the inverting input terminal of the first operational amplifier OP1 is connected to the output terminal of the first operational amplifier OP1 through the resistor R4, the output terminal of the first operational amplifier OP1 is connected to the anode of the voltage-stabilizing diode Z through the capacitor C1, and the output terminal of the first operational amplifier OP1 is connected to the input terminal of the secondary modulation circuit;

[0013] The anode of the first operational amplifier OP1 is connected to the cathode of the voltage zener diode Z, and the cathode of the first operational amplifier OP1 is connected to the anode of the voltage zener diode Z.

[0014] Further, in the non-isolated high-side current sampling circuit of the present invention, the secondary modulation circuit includes a second operational amplifier OP2, a resistor R8, and a resistor R9;

[0015] The non-inverting input terminal of the second operational amplifier OP2 is connected to the output terminal of the first operational amplifier OP1, the inverting input terminal of the second operational amplifier OP2 is connected to the emitter of the transistor Q, and the output terminal of the second operational amplifier OP2 is connected to the base of the transistor Q; the emitter of the transistor Q is connected to the second end of the resistor R1 through the resistor R9;

[0016] The anode of the second operational amplifier OP2 is connected to the cathode of the voltage zener diode Z, and the cathode of the second operational amplifier OP2 is connected to the anode of the voltage zener diode Z.

[0017] Furthermore, the non-isolated high-side current sampling circuit of the present invention further includes a resistor R10, a first end of the resistor R10 is connected to the collector of the transistor Q, and a second end of the resistor R10 is connected to the first end of the resistor R11.

[0018] Furthermore, in the non-isolated high-side current sampling circuit described in the present invention, the transistor Q is a PNP transistor.

[0019] Further, in the non-isolated high-side current sampling circuit described in the present invention, the output voltage of the DC power supply is between 24V and 100V;

[0020] The resistance of the high-side sampling resistor R1 is less than 100 mΩ.

[0021] In addition, the present invention also provides a direct current power supply, comprising the non-isolated high-side current sampling circuit as described above.

[0022] A non-isolated high-side current sampling circuit and a DC power supply implementing the present invention have the following beneficial effects: the present invention solves the problem in the prior art that the amplifier cannot withstand a higher common-mode voltage when directly sampling is used, and can be used in DC bus protection with a voltage of 24V to 100V, thereby effectively improving the reliability of the DC power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0024] Figure 1 is a structural schematic diagram of a non-isolated high-side current sampling circuit provided in Example 1;

[0025] Figure 2 is a structural schematic diagram of a non-isolated high-side current sampling circuit provided in Example 2;

[0026] Figure 3 This is a circuit diagram of a non-isolated high-side current sampling circuit provided in Example 3. DETAILED DESCRIPTION

[0027] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0028] Example 1

[0029] refer to Figure 1 The non-isolated high-side current sampling circuit of this embodiment includes a high-side sampling resistor R1, a voltage-regulating diode voltage-dividing circuit 10, a first-stage amplifier circuit 20, a second-stage modulation circuit 30, a transistor Q, and a low-side sampling resistor R11. The first end of the high-side sampling resistor R1 is connected to the DC bus of the DC power supply, the second end of the high-side sampling resistor R1 is connected to the emitter of the transistor Q, and the second end of the high-side sampling resistor R1 is connected to the load; the high-side sampling resistor R1 is connected to the input end of the first-stage amplifier circuit 20, the sampling voltage of the high-side sampling resistor R1 is input to the first-stage amplifier circuit 20, the output end of the first-stage amplifier circuit 20 is connected to the input end of the second-stage modulation circuit 30, and the output end of the second-stage modulation circuit 30 is connected to the base of the transistor Q; the collector of the transistor Q is connected to the first end of the low-side sampling resistor R11, the second end of the low-side sampling resistor R11 is connected to the negative electrode of the DC power supply, and the negative electrode of the DC power supply is grounded.

[0030] The voltage divider circuit 10 divides the voltage of 5V-10V from the DC bus and constructs a floating ground terminal for use by the primary amplifier circuit 20 and the secondary modulation circuit 30. The primary amplifier circuit 20 amplifies the voltage signal of the high-side sampling resistor R1 and outputs it to the secondary modulation circuit 30 after amplification. The secondary modulation circuit 30 adjusts the opening of the transistor Q according to the output voltage of the primary amplifier circuit 20 and performs negative feedback. The output current of the transistor Q is converted into a voltage signal output through the low-side sampling resistor R11.

[0031] As an option, in the non-isolated high-side current sampling circuit of this embodiment, the output voltage of the DC power supply is between 24V and 100V; and the resistance value of the high-side sampling resistor R1 is less than 100mΩ.

[0032] Alternatively, in the non-isolated high-side current sampling circuit of this embodiment, the transistor Q is a PNP transistor.

[0033] This embodiment solves the problem in the prior art that the amplifier cannot withstand a higher common-mode voltage when directly sampling is used, and is applicable to DC bus protection with a voltage of 24V to 100V, thereby effectively improving the reliability of the DC power supply.

[0034] Example 2

[0035] refer to Figure 2 Based on Example 1, the non-isolated high-side current sampling circuit of this embodiment further includes an output amplifier circuit 40 connected to the low-side sampling resistor R11, and the output amplifier circuit 40 is used to amplify the voltage across the low-side sampling resistor R11.

[0036] This embodiment solves the problem in the prior art that the amplifier cannot withstand a higher common-mode voltage when directly sampling is used, and is applicable to DC bus protection with a voltage of 24V to 100V, thereby effectively improving the reliability of the DC power supply.

[0037] Example 3

[0038] refer to Figure 3 On the basis of the above-mentioned embodiment, the voltage-regulating diode voltage-dividing circuit 10 in the non-isolated high-side current sampling circuit of this embodiment includes a voltage-regulating diode Z and a resistor R7, the cathode of the voltage-regulating diode Z is connected to the DC bus, and the anode of the voltage-regulating diode Z is connected to the cathode of the DC power supply through the resistor R7. The voltage-regulating diode Z and the resistor R7 form a relatively stable floating ground terminal, the potential of which relative to the cathode of the power supply bus is Vf, and the voltage difference between the anode voltage of the DC bus and the floating ground is the voltage drop of the voltage-regulating diode Z, which is about 5V. The cathode of the voltage-regulating diode Z serves as the anode power supply of the primary amplifier circuit 20 and the secondary modulation circuit 30, and the anode of the voltage-regulating diode Z serves as the floating ground terminal of the primary amplifier circuit 20 and the secondary modulation circuit 30.

[0039] The first-stage amplifier circuit 20 in the non-isolated high-side current sampling circuit of this embodiment includes a first operational amplifier OP1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, and a capacitor C1. The non-inverting input terminal of the first operational amplifier OP1 is connected to the first end of the resistor R1 through the resistor R2, and the non-inverting input terminal of the first operational amplifier OP1 is connected to the positive electrode of the voltage-stabilizing diode Z through the resistor R5; the inverting input terminal of the first operational amplifier OP1 is connected to the second end of the resistor R1 through the resistor R3, and the inverting input terminal of the first operational amplifier OP1 is connected to the output terminal of the first operational amplifier OP1 through the resistor R4. The output terminal of the first operational amplifier OP1 is connected to the positive electrode of the voltage-stabilizing diode Z through the capacitor C1, and the output terminal of the first operational amplifier OP1 is connected to the input terminal of the secondary modulation circuit 30. The positive electrode of the first operational amplifier OP1 is connected to the negative electrode of the voltage-stabilizing diode Z, and the negative electrode of the first operational amplifier OP1 is connected to the positive electrode of the voltage-stabilizing diode Z.

[0040] The current of the DC bus flows through the high-side sampling resistor R1, and a certain voltage drop will be generated on the high-side sampling resistor R1, which is input into the first-stage amplifier circuit 20. However, in order to avoid introducing too high impedance to cause voltage division, the resistance value of the high-side sampling resistor R1 in this embodiment is less than 100mΩ. As an option, the amplification factor of the first-stage amplifier circuit 20 is 10-20 times, which can be selected as needed.

[0041] The secondary modulation circuit 30 in the non-isolated high-side current sampling circuit of this embodiment includes a second operational amplifier OP2, a resistor R8, and a resistor R9. The non-inverting input terminal of the second operational amplifier OP2 is connected to the output terminal of the first operational amplifier OP1, the inverting input terminal of the second operational amplifier OP2 is connected to the emitter of the transistor Q, and the output terminal of the second operational amplifier OP2 is connected to the base of the transistor Q; the emitter of the transistor Q is connected to the second end of the resistor R1 through the resistor R9, the inverting input terminal of the second operational amplifier OP2 and the low side of the resistor R9 form a negative feedback loop, and the output terminal of the second operational amplifier OP2 outputs a signal to the base of the transistor Q to control the opening of the transistor Q. The positive electrode of the second operational amplifier OP2 is connected to the negative electrode of the voltage-stabilizing diode Z, and the negative electrode of the second operational amplifier OP2 is connected to the positive electrode of the voltage-stabilizing diode Z. As an option, transistor Q is a PNP transistor, which cooperates with a current limiting resistor to convert a voltage signal into a current signal, while bearing the voltage stress on the DC bus. The generated current signal flows along the branch to the low side, realizing the transmission of the high side signal to the low side signal.

[0042] The non-isolated high-side current sampling circuit of this embodiment further includes a resistor R10 , a first end of the resistor R10 is connected to the collector of the transistor Q, and a second end of the resistor R10 is connected to a first end of a resistor R11 .

[0043] The output amplifier circuit 40 in the non-isolated high-side current sampling circuit of this embodiment includes a third operational amplifier OP3, a resistor R12, a resistor R13, a resistor R14, a resistor R15, and a capacitor C2. The inverting input terminal of the third operational amplifier OP3 is connected to the first end of the resistor R12, the second end of the resistor R12 is connected to the first end of the low-side sampling resistor R11, the second end of the resistor R12 is grounded through the capacitor C2, and the inverting input terminal of the third operational amplifier OP3 is connected to the output terminal of the third operational amplifier OP3 through the resistor R13; the non-inverting input terminal of the third operational amplifier OP3 is connected to the power supply voltage VCC through the resistor R14, and the non-inverting input terminal of the third operational amplifier OP3 is grounded through the resistor R15.

[0044] The present invention aims to solve two difficulties in high-side current sampling: the high cost and low accuracy and linearity when using an isolated high-side sampling solution; and the high common-mode voltage cannot be tolerated when using an amplifier for direct sampling, which introduces measurement errors and the risk of amplifier breakdown. The voltage-current-voltage signal conversion is realized through a set of low-cost analog circuits, and the high-side signal is transferred to the low side, taking into account both cost and performance. The present invention will have broad application prospects in 24V-100V DC bus protection. Detecting the amplitude of the high-side current signal to perform the corresponding protection action is the basis for realizing power supply protection. The scheme can effectively improve the reliability of various types of equipment that use lithium battery packs and lead-acid battery packs to provide DC power.

[0045] Example 3

[0046] In addition, this embodiment further provides a DC power supply, including the non-isolated high-side current sampling circuit as described above.

[0047] This embodiment solves the problem in the prior art that the amplifier cannot withstand a higher common-mode voltage when directly sampling is used, and is applicable to DC bus protection with a voltage of 24V to 100V, thereby effectively improving the reliability of the DC power supply.

[0048] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot limit the scope of protection of the present invention. All equivalent changes and modifications made to the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A non-isolated high-side current sampling circuit, characterized in that: It comprises a high-side sampling resistor R1, a voltage-regulating tube voltage-dividing circuit (10), a first-stage amplifying circuit (20), a second-stage modulation circuit (30), a transistor Q, and a low-side sampling resistor R11; The first end of the high-side sampling resistor R1 is connected to the DC bus of the DC power supply, the second end of the high-side sampling resistor R1 is connected to the emitter of the transistor Q, and the second end of the high-side sampling resistor R1 is connected to the load; the high-side sampling resistor R1 is connected to the input end of the primary amplifier circuit (20), the sampling voltage of the high-side sampling resistor R1 is input to the primary amplifier circuit (20), the output end of the primary amplifier circuit (20) is connected to the input end of the secondary modulation circuit (30), and the output end of the secondary modulation circuit (30) is connected to the base of the transistor Q; the collector of the transistor Q is connected to the first end of the low-side sampling resistor R11, the second end of the low-side sampling resistor R11 is connected to the negative electrode of the DC power supply, and the negative electrode of the DC power supply is grounded.

2. The non-isolated high-side current sampling circuit according to claim 1, characterized in that: It also includes an output amplifier circuit (40) connected to the low-side sampling resistor R11, and the output amplifier circuit (40) is used to amplify the voltage across the two ends of the low-side sampling resistor R11.

3. The non-isolated high-side current sampling circuit according to claim 2, characterized in that: The output amplifier circuit (40) comprises a third operational amplifier OP3, a resistor R12, a resistor R13, a resistor R14, a resistor R15, and a capacitor C2; The inverting input terminal of the third operational amplifier OP3 is connected to the first end of the resistor R12, the second end of the resistor R12 is connected to the first end of the low-side sampling resistor R11, the second end of the resistor R12 is grounded through the capacitor C2, and the inverting input terminal of the third operational amplifier OP3 is connected to the output terminal of the third operational amplifier OP3 through the resistor R13; the non-inverting input terminal of the third operational amplifier OP3 is connected to the power supply voltage VCC through the resistor R14, and the non-inverting input terminal of the third operational amplifier OP3 is grounded through the resistor R15.

4. The non-isolated high-side current sampling circuit according to claim 1, characterized in that: The voltage-regulating diode voltage-dividing circuit (10) comprises a voltage-regulating diode Z and a resistor R7; The cathode of the voltage stabilizing diode Z is connected to the DC bus, and the anode of the voltage stabilizing diode Z is connected to the cathode of the DC power supply via the resistor R7; the cathode of the voltage stabilizing diode Z serves as the anode of the power supply for the primary amplifier circuit (20) and the secondary modulation circuit (30), and the anode of the voltage stabilizing diode Z serves as the floating ground terminal of the primary amplifier circuit (20) and the secondary modulation circuit (30).

5. The non-isolated high-side current sampling circuit according to claim 4, characterized in that: The first-stage amplifier circuit (20) comprises a first operational amplifier OP1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, and a capacitor C1; The non-inverting input terminal of the first operational amplifier OP1 is connected to the first end of the resistor R1 through the resistor R2, and the non-inverting input terminal of the first operational amplifier OP1 is connected to the positive electrode of the voltage-stabilizing diode Z through the resistor R5; the inverting input terminal of the first operational amplifier OP1 is connected to the second end of the resistor R1 through the resistor R3, and the inverting input terminal of the first operational amplifier OP1 is connected to the output terminal of the first operational amplifier OP1 through the resistor R4, and the output terminal of the first operational amplifier OP1 is connected to the positive electrode of the voltage-stabilizing diode Z through the capacitor C1, and the output terminal of the first operational amplifier OP1 is connected to the input terminal of the secondary modulation circuit (30); The anode of the first operational amplifier OP1 is connected to the cathode of the voltage zener diode Z, and the cathode of the first operational amplifier OP1 is connected to the anode of the voltage zener diode Z.

6. The non-isolated high-side current sampling circuit according to claim 5, characterized in that: The secondary modulation circuit (30) comprises a second operational amplifier OP2, a resistor R8, and a resistor R9; The non-inverting input terminal of the second operational amplifier OP2 is connected to the output terminal of the first operational amplifier OP1, the inverting input terminal of the second operational amplifier OP2 is connected to the emitter of the transistor Q, and the output terminal of the second operational amplifier OP2 is connected to the base of the transistor Q; the emitter of the transistor Q is connected to the second end of the resistor R1 through the resistor R9; The anode of the second operational amplifier OP2 is connected to the cathode of the voltage zener diode Z, and the cathode of the second operational amplifier OP2 is connected to the anode of the voltage zener diode Z.

7. The non-isolated high-side current sampling circuit according to claim 6, characterized in that: A resistor R10 is also included, a first end of the resistor R10 is connected to the collector of the transistor Q, and a second end of the resistor R10 is connected to the first end of the resistor R11.

8. The non-isolated high-side current sampling circuit according to claim 1, characterized in that: The transistor Q is a PNP transistor.

9. The non-isolated high-side current sampling circuit according to claim 1, characterized in that: The output voltage of the DC power supply is between 24V and 100V; The resistance of the high-side sampling resistor R1 is less than 100 mΩ.

10. A DC power supply, characterized in that: The invention comprises the non-isolated high-side current sampling circuit as claimed in any one of claims 1 to 9.

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