High-bandwidth current acquisition circuit, switching power supply and acquisition method

Abstract

The invention relates to the technical field of automatic control, in particular to a high-bandwidth current acquisition circuit, a switching power supply and an acquisition method. Comprising a sampling resistor Rs used for being connected in series in a current path; the differential current mirror circuit is composed of NPN pair transistors and used for detecting the voltage difference between the two ends of the sampling resistor; the mirror current source compensation circuit consists of PNP geminate transistors and is used for compensating geminate transistor current with low emitter voltage; the bias circuit is used for dividing voltage through the resistance value of a bias resistor; the amplifying circuit is used for amplifying a voltage drop signal on the sampling resistor; and the filtering output circuit is used for filtering noise and providing a stable output voltage signal. The bandwidth of a traditional Hall sensor limits the speed of current collection, but the circuit can effectively collect current signals which change over 800 kHz, the frequency response capability of current collection is greatly improved, and the current collection circuit is suitable for a power supply system with higher switching frequency.

Description

Technical Field

[0001] The present invention relates to the field of automatic control technology, and in particular to a high-bandwidth current acquisition circuit, a switching power supply and an acquisition method. Background Art

[0002] In recent years, switching power supplies have faced higher requirements in many industries such as aerospace, electric vehicle onboard chargers, and communication power supplies. With the development of science and technology, the demand for switching power supplies in these fields is no longer limited to traditional performance indicators, but pays more attention to high reliability, high efficiency, and high power density. In order to achieve these goals, on the one hand, the efficiency of the power supply can be improved by improving the circuit topology and selecting low-loss switching devices and magnetic components; on the other hand, the power density of the converter can be improved by selecting power devices with faster switching speeds and reducing the size of magnetic components.

[0003] However, as the switching frequency continues to increase, it also poses new challenges to other related circuits, especially the acquisition of the input and output current of the power supply. Accurate and fast acquisition of current information is essential to ensure the safe operation of the entire power system. Traditionally, aerospace-grade Hall current sensors are used for current acquisition, but their bandwidth is usually limited to about 1kHz. Even industrial-grade high-speed Hall sensors have a bandwidth of only about 100kHz, which is far from meeting the current acquisition requirements at switching frequencies of 800kHz and higher. In addition, traditional current acquisition circuits can only support the acquisition of a single output current. When it is necessary to simultaneously acquire two output currents, two independent acquisition circuits are often required, and the actual total output current size is reflected by summing. This method increases the complexity and cost of the system. Summary of the invention

[0004] The present invention provides a high-bandwidth current acquisition circuit, a switching power supply and an acquisition method, the purpose of which is to form a new high-speed current acquisition solution composed of discrete devices, which is suitable for high-reliability and high-precision current acquisition in spacecraft applications, and lays the foundation for the application of power conversion systems with higher operating frequency, greater power density and higher conversion efficiency in spacecraft systems.

[0005] To achieve the above object, the technical solution of the present invention is:

[0006] The present invention provides a high-bandwidth current acquisition circuit, comprising:

[0007] The sampling resistor Rs includes a resistor Rs1 and a resistor Rs2, which are connected in series in the current path;

[0008] The differential current mirror circuit composed of NPN pair tubes is used to detect the voltage difference across the sampling resistor;

[0009] The mirror current source compensation circuit composed of a PNP pair of tubes is used to compensate for the pair current with low emitter voltage and convert the compensation current signal into a voltage signal;

[0010] The bias circuit divides the voltage through the bias resistor, so that the collected signal has a bias output when the current is zero;

[0011] An amplifier circuit, used for amplifying a voltage drop signal on the sampling resistor;

[0012] The filter output circuit is used to filter out noise and provide a stable output voltage signal.

[0013] Furthermore, the resistance values ​​of the resistors Rs1 and Rs2 in the sampling resistor Rs are equal, and the voltage drop △V on the sampling resistor is proportional to the current Io1 flowing through the resistor Rs1 and the current Io2 flowing through the resistor Rs2, satisfying the formula:

[0014] △V= Rs1×Io1+ Rs2×Io2

[0015] = Rs × (Io1 + Io2).

[0016] Furthermore, the gain β in the amplifier circuit is determined by the ratio of the resistors R8 and R4, satisfying the formula:

[0017] β = (R8 ÷ R4),

[0018] And the amplified output voltage V1 is linearly related to the total current on the sampling resistor, satisfying the formula:

[0019] V1 = β × Rs × (Io1 + Io2) + Vz, where Vz is the bias voltage.

[0020] Furthermore, the bias voltage Vz is obtained by voltage division of the bias resistor R9 and the resistor R8, so that when the current is zero, the acquisition signal has a non-zero initial output voltage.

[0021] Furthermore, the circuit can effectively collect current signals that change above 800kHz, and realize the function of simultaneously collecting dual-channel output currents. When any channel of output current changes, the change amplitude of the current can be accurately detected.

[0022] Furthermore, the circuit is suitable for spacecraft applications and is used in situations where high reliability and high precision current acquisition are required, including 30W, 65W and 150W series of power supply products.

[0023] A switching power supply is used to collect the input and output currents of the power supply at high speed and precision, thereby ensuring the stability and reliability of the system.

[0024] A power conversion system is used to monitor current changes in real time, support fast dynamic response, and achieve efficient energy conversion.

[0025] A high bandwidth current acquisition method, the method comprising the following steps:

[0026] Connect the sampling resistor in series into the current path;

[0027] The voltage difference across the sampling resistor is detected by a differential current mirror circuit;

[0028] Compensating the current by using a mirror current source compensation circuit and converting the compensated current into a voltage signal;

[0029] Setting a bias voltage through a bias circuit;

[0030] Amplify the voltage signal through an amplifier circuit;

[0031] A stable voltage signal is output through the filter output circuit and used to feed back to the control system for closed-loop control or output current telemetry.

[0032] Furthermore, the method is suitable for spacecraft applications, especially in cases where high reliability and high precision current acquisition are required, such as in 30W, 65W and 150W series of power supply products.

[0033] The beneficial effects achieved by the present invention are:

[0034] The present invention provides a high-bandwidth current acquisition circuit. The bandwidth of a traditional Hall sensor limits the speed of current acquisition, while the circuit of the present invention can effectively acquire current signals that vary above 800kHz, greatly improving the frequency response capability of current acquisition, making it suitable for power supply systems with higher switching frequencies.

[0035] The invention discloses a high-bandwidth current acquisition circuit. Different from the traditional single-channel acquisition method, the invention realizes the simultaneous acquisition function of dual-channel output currents. This not only simplifies the complexity of the system and reduces the cost, but also improves the monitoring accuracy and reliability of the multi-output power supply system.

[0036] The invention discloses a high-bandwidth current acquisition circuit, which ensures the linearity and accuracy of current acquisition by using components such as sampling resistors, differential current mirror circuits, and amplifier circuits. Even when the current is zero, a non-zero initial output voltage can be obtained due to the presence of a bias voltage, thereby avoiding a measurement blind area.

[0037] The invention discloses a high-bandwidth current acquisition circuit. The design of the filter output circuit effectively reduces the influence of external interference on current acquisition and ensures the stability of the output voltage signal, which is particularly important for applications requiring high-precision current monitoring.

[0038] The present invention provides a high-bandwidth current acquisition circuit, which is particularly suitable for spacecraft applications, including but not limited to 30W, 65W and 150W series power supply products. It can meet the needs of these occasions for high reliability and high-precision current acquisition, and ensure the stable operation and fast dynamic response of the power conversion system.

[0039] The invention discloses a high-bandwidth current acquisition circuit. Accurately and quickly acquiring current information is essential to ensure the safe operation of the entire power supply system. The high-bandwidth current acquisition solution provided by the invention helps to monitor current changes in real time, supports rapid adjustment and protection mechanisms, and thus enhances the safety and reliability of the system.

[0040] The present invention provides a switching power supply, which brings new technical solutions to the field of switching power supplies, promotes the development of related technologies, and lays a foundation for more efficient and intelligent power conversion systems in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0042] Figure 1 This is a schematic diagram of a high-bandwidth current acquisition circuit;

[0043] Figure 2 A high bandwidth current acquisition circuit diagram;

[0044] Figure 3 When the +12V output current and -12V output current are 5A respectively, the output waveform is sampled;

[0045] Figure 4 When the +12V output current and -12V output current are 0A and 10A respectively, the output waveform is sampled;

[0046] Figure 5 When the +12V output current and -12V output current are 8A and 2A respectively, the output waveform is sampled;

[0047] Figure 6 When the high frequency changes at 1MHz, the current sampling output waveform;

[0048] Figure 1 Among them, 1. current sampling resistor; 2. differential current sampling circuit; 3. mirror compensation circuit; 4. amplifier circuit; 5. bias resistor; 6. filter output circuit.

[0049] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0050] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0052] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if the meaning of "and / or" appearing in the full text is to include three parallel schemes, taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0053] like Figure 1 and Figure 2 As shown, the present invention provides a high-bandwidth current acquisition circuit, comprising:

[0054] The sampling resistor Rs includes resistors Rs1 and Rs2, which are connected in series in the current path. When current flows through the sampling resistor, a voltage drop proportional to the current (△V = Rs× Io) will be generated at both ends of the sampling resistor, and this voltage drop will serve as the input signal of the subsequent current mirror and amplifier circuit.

[0055] The differential current mirror circuit composed of NPN pair tubes is used to detect the voltage difference across the sampling resistor;

[0056] The differential current mirror circuit consists of a pair of NPN transistors, which are used to detect the voltage difference across the sampling resistor and convert it into a current signal. This design can effectively improve the sensitivity of the measurement and reduce the impact of common-mode interference.

[0057] Two well-matched NPN transistors (such as BC547) are used to form a differential pair, with their bases connected to both ends of the sampling resistor. The emitter is grounded through a small resistor, and the collector is connected to the power supply and the mirror current source compensation circuit of the next stage.

[0058] The mirror current source compensation circuit composed of a PNP pair of tubes is used to compensate for the pair current with low emitter voltage and convert the compensation current signal into a voltage signal;

[0059] This circuit consists of a pair of PNP transistors and is designed to compensate for the current error caused by the low emitter voltage in the differential current mirror circuit. In addition, it converts the compensated current signal into a voltage signal for subsequent amplification processing.

[0060] Choose two high-gain, low-noise PNP transistors (such as BC557), connect their bases to the collectors of the differential current mirror, connect their emitters to the power supply through a resistor, and connect their collectors to ground through another resistor. In this way, the current change can be converted into a corresponding voltage change.

[0061] The bias circuit divides the voltage through the bias resistor, so that the collected signal has a bias output when the current is zero;

[0062] The role of the bias circuit is to provide a stable non-zero initial output voltage (Vz) under zero current output conditions. This helps avoid the measurement blind area that may occur under low current or zero current conditions and improves the linearity of the entire system.

[0063] This is achieved through a voltage divider network, that is, using two resistors (R9 and R8) to divide the power supply voltage to obtain the required bias voltage Vz. R9 and R8 should be selected to ensure that the output voltage remains at a suitable level when there is no input current.

[0064] An amplifier circuit, used for amplifying a voltage drop signal on the sampling resistor;

[0065] The task of the amplifier circuit is to amplify the weak voltage signal to a level sufficient to drive the back-end control circuit. In order to maintain the linearity and accuracy of the signal, the amplifier should have a high input impedance and a low output impedance. Use an operational amplifier (such as OPA2376) to build a non-inverting amplifier configuration. Set the desired gain β by adjusting the ratio of the feedback resistor (R8) and the input resistor (R4).

[0066] The filter output circuit is used to filter out noise and provide a stable output voltage signal.

[0067] The filter output circuit is used to remove high-frequency noise from the amplified voltage signal to ensure that the output is a smooth and stable DC voltage signal, which is very important for accurately reflecting the actual current condition.

[0068] An RC low-pass filter is used, where capacitor C1 is connected in series with resistor R10 between the output of the amplifier and ground. The selection of capacitor C1 depends on the expected maximum switching frequency to ensure that the filter does not attenuate signals within the target frequency range.

[0069] The resistance values ​​of the resistors Rs1 and Rs2 in the sampling resistor Rs are equal, and the voltage drop △V on the sampling resistor is proportional to the current Io1 flowing through the resistor Rs1 and the current Io2 flowing through the resistor Rs2, satisfying the formula:

[0070] △V= Rs1×Io1+ Rs2×Io2= Rs × (Io1 + Io2).

[0071] The gain β in the amplifier circuit is determined by the ratio of the resistors R8 and R4, satisfying the formula: β = (R8 ÷ R4), and the amplified output voltage V1 is linearly related to the total current on the sampling resistor, satisfying the formula: V1 = β × Rs ×(Io1 + Io2) + Vz, where Vz is the bias voltage.

[0072] The bias voltage Vz is obtained by voltage division of the bias resistor R9 and the (pair of) resistors R8, so that when the current is zero, the sampled signal has a non-zero initial output voltage.

[0073] The circuit can effectively collect current signals that change above 800kHz, and realize the function of simultaneously collecting dual-channel output currents. When any channel of output current changes, the change amplitude of the current can be accurately detected.

[0074] The circuit is suitable for spacecraft applications and is used in situations where high reliability and high precision current acquisition are required, including 30W, 65W and 150W series of power supply products.

[0075] A switching power supply is used to collect the input and output currents of the power supply at high speed and precision, thereby ensuring the stability and reliability of the system.

[0076] A power conversion system is used to monitor current changes in real time, support fast dynamic response, and achieve efficient energy conversion.

[0077] A high bandwidth current acquisition method, the method comprising the following steps:

[0078] A sampling resistor is connected in series to a current path; a voltage difference across the sampling resistor is detected by a differential current mirror circuit; the current is compensated by a mirror current source compensation circuit and the compensated current is converted into a voltage signal; a bias voltage is set by a bias circuit; the voltage signal is amplified by an amplifier circuit; a stable voltage signal is output by a filter output circuit to be fed back to a control system for closed-loop control or output current telemetry.

[0079] Specific steps:

[0080] Step 1: Connect the sampling resistors Rs1 and Rs2 in series to the current path respectively, and prepare for current detection.

[0081] Step 2: Use a differential current mirror circuit to detect the voltage difference across the sampling resistor and convert it into a current signal.

[0082] Step 3: The current signal is further processed by the mirror current source compensation circuit to eliminate the error and convert it into a voltage signal.

[0083] Step 4: Set up the bias circuit so that there is a stable initial output voltage even at zero current.

[0084] Step 5: Use an amplifier circuit to amplify the voltage signal processed in the previous steps to reach an amplitude suitable for use in the control system.

[0085] Step 6: After the output filter circuit removes noise, a clean and stable voltage signal is finally obtained, which can be directly used for closed-loop control or output current telemetry.

[0086] The method is suitable for spacecraft applications, especially in cases where high reliability and high precision current acquisition are required, such as in 30W, 65W and 150W series power supply products.

[0087] like Figure 1 As shown, the present invention designs a high-bandwidth current acquisition circuit through discrete devices, converts the output current signal into a linear output voltage signal, and can increase the bias voltage through a bias circuit.

[0088] The high-bandwidth current acquisition circuit is composed of discrete triodes and resistor-capacitor devices. The sampling resistor is connected in series in the current path. The voltage difference across the sampling resistor is detected by a differential current mirror circuit composed of an NPN pair of tubes. The mirror current source principle is used to compensate the current of the pair of tubes with low emitter voltage through an external circuit. A mirror current source compensation circuit composed of a PNP pair of tubes is set at the compensation end. Through the mirror current source principle, the other pair of tubes in the PNP pair of tubes converts the compensation current signal into a voltage signal, and the output current signal can be converted into a linearly transformed voltage signal.

[0089] At the same time, a bias circuit is designed at the acquisition end. Through the resistance division of the bias resistor, the acquisition signal can have a bias output when the current is zero.

[0090] like Figure 2 As shown, the currents Io1 and Io2 flowing through the sampling resistors Rs1 and Rs2 generate a voltage drop △V on the resistors;

[0091] △V=Rs1×Io1+Rs2×Io2 (1)

[0092] In circuit design, usually: Rs1= Rs2= Rs;

[0093] That is, △V = Rs × (Io1 + Io2) (2)

[0094] After the △V voltage is amplified, it is obtained on the R8 resistor:

[0095] V1=(R8÷R4)×△V+Vz (3)

[0096] Where Vz is the bias voltage, which is also the voltage divider value of R9 and R8.

[0097] Substituting formula (2) into (3) yields:

[0098] V1=β×Rs×(Io1+Io2) +Vz (4)

[0099] Where β = (R8 ÷ R4)

[0100] From formula (4), we can see that V1 is a function related to Io1+Io2 and has a linear relationship. The change value of Io1+Io2 can be linearly equivalent through the voltage of V1.

[0101] After being filtered by R12 and C2, the V1 voltage can be fed back to the system control end for closed-loop control or output current telemetry, achieving high-speed and accurate acquisition of current values.

[0102] In the ±12V power converter, when the +12V output current and -12V output current are both 5A, the output current waveform and the collected voltage are as follows: Figure 3 The following are the sampled output waveforms when the output is 5A; Figure 4 The sampled output waveforms are as follows when the output is 0A and 10A respectively; Figure 5 When the output is 8A and 2A respectively, the output waveform is sampled; when the output current fluctuates at a high frequency above 1MHz, the sampling signal can accurately feedback the amplitude of the current change and change linearly with the change of the current. Figure 6 As shown in the figure, the current sampling output waveform when the high frequency changes at 1MHz.

[0103] Based on the design of the above sampling circuit scheme and other power circuits, the development of a new generation of GaN series power module products has been completed. The product conversion efficiency has reached more than 90% under rated conditions and has passed the space single particle and total dose simulation tests, proving that this circuit can meet space applications.

[0104] This sampling circuit is completely designed based on discrete devices. The circuit is simple and reliable. After experimental verification, it is proved that its effect meets the sampling requirements of high-reliability, high-efficiency and high-power density switching power supply devices.

[0105] The above descriptions are only optional embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A high bandwidth current acquisition circuit, characterized in that: include: The sampling resistor Rs includes a resistor Rs1 and a resistor Rs2, which are connected in series in the current path; The differential current mirror circuit composed of NPN pair tubes is used to detect the voltage difference across the sampling resistor; The mirror current source compensation circuit composed of a PNP pair of tubes is used to compensate for the pair current with low emitter voltage and convert the compensation current signal into a voltage signal; The bias circuit divides the voltage through the bias resistor, so that the collected signal has a bias output when the current is zero; An amplifier circuit, used for amplifying a voltage drop signal on the sampling resistor; The filter output circuit is used to filter out noise and provide a stable output voltage signal.

2. The high-bandwidth current acquisition circuit according to claim 1, characterized in that: The resistance values ​​of the resistors Rs1 and Rs2 in the sampling resistor Rs are equal, and the voltage drop △V on the sampling resistor is proportional to the current Io1 flowing through the resistor Rs1 and the current Io2 flowing through the resistor Rs2, satisfying the formula: △V= Rs1×Io1+ Rs2×Io2 = Rs × (Io1 + Io2).

3. The high-bandwidth current acquisition circuit according to claim 2, characterized in that: The gain β in the amplifier circuit is determined by the ratio of the resistors R8 and R4, satisfying the formula: β = (R8 ÷ R4), And the amplified output voltage V1 is linearly related to the total current on the sampling resistor, satisfying the formula: V1 = β × Rs × (Io1 + Io2) + Vz, where Vz is the bias voltage Vz.

4. The high-bandwidth current acquisition circuit according to claim 3, characterized in that: The bias voltage Vz is obtained by voltage division of the bias resistor R9 and the resistor R8, so that when the current is zero, the acquisition signal has a non-zero initial output voltage.

5. The high-bandwidth current acquisition circuit according to claim 4, characterized in that: The acquisition circuit can acquire current signals that change at a frequency of more than 800kHz and realize the function of simultaneously acquiring dual-channel output currents. When any channel of output current changes, the change amplitude of the current can be accurately detected.

6. The high-bandwidth current acquisition circuit according to claim 5, characterized in that: The circuit is suitable for spacecraft applications and is used in situations where high reliability and high precision current acquisition are required, including 30W, 65W and 150W series of power supply products.

7. A switching power supply, characterized in that: The high-bandwidth current acquisition circuit as claimed in any one of claims 1 to 6 is used to acquire the input and output currents of the power supply at high speed and accurately, thereby ensuring the stability and reliability of the system.

8. A high bandwidth current acquisition method, characterized in that: The method comprises using the high-bandwidth current acquisition circuit as claimed in any one of claims 1 to 6 to acquire a current signal, and the method comprises the following steps: Connect the sampling resistor in series into the current path; The voltage difference across the sampling resistor is detected by a differential current mirror circuit; Compensating the current by using a mirror current source compensation circuit and converting the compensated current into a voltage signal; Setting a bias voltage through a bias circuit; amplify the voltage signal through an amplifier circuit; A stable voltage signal is output through the filter output circuit and used to feed back to the control system for closed-loop control or output current telemetry.

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