Current sampling circuit and fan drive system

Abstract

The current sampling circuit and fan drive system provided by the present invention have a first sampling interface, a first level adjustment module and a first sampling port which are electrically connected in sequence, and a second sampling interface, a second level adjustment module and a second sampling port which are electrically connected in sequence. By setting the first level adjustment module and the second level adjustment module, the voltage conversion function at the first sampling interface and the second sampling interface to the voltage at the first sampling port and the second sampling port is realized, thereby providing a suitable voltage reference for sampling; at the same time, since the impedance of the first level adjustment module is symmetrical with the impedance of the second level adjustment module, and the impedance of the first sampling port is symmetrical with the impedance of the second sampling port, common mode interference can be effectively suppressed; that is, the circuit provided by the present invention can also filter interference and collect high-precision data without using an operational amplifier, which not only meets the use requirements but also saves costs.

Description

Technical Field

[0001] The present invention relates to the field of analog integrated circuit design, and in particular to a current sampling circuit and a fan drive system. Background Art

[0002] With the development of information technology and semiconductor technology, integrated circuits (ICs) are widely used in various electronic devices to achieve small size, high speed and low power consumption. As an important module of analog ICs, current detection circuits have been widely used in current protection / monitoring equipment, programmable current sources, linear / switching power supplies, and various chargers and battery fuel gauges.

[0003] At present, the core module of the current detection circuit is mainly composed of high-precision sampling resistors and high-gain operational amplifiers. Among them, the high-gain operational amplifier not only causes the circuit to consume more power, but also has a high price, which does not meet the demand for the continuous pursuit of low cost of commodities. Summary of the invention

[0004] In view of this, the present invention provides a current sampling circuit and a fan driving system to solve the problem of how to realize current and / or voltage acquisition without using an operational amplifier.

[0005] In a first aspect, an embodiment provides a current sampling circuit, the current sampling circuit comprising: a first sampling interface, a second sampling interface, a first level adjustment module, a second level adjustment module and a sampling module, the sampling module comprising a first sampling port and a second sampling port, the first sampling interface, the first level adjustment module and the first sampling port are electrically connected in sequence, the second sampling interface, the second level adjustment module and the second sampling port are electrically connected in sequence, the impedance of the first level adjustment module is symmetrical with the impedance of the second level adjustment module, and the impedance of the first sampling port is symmetrical with the impedance of the second sampling port;

[0006] The first level adjustment module is used for converting the first voltage of the first sampling interface into a second voltage, and transmitting the second voltage to the first sampling port;

[0007] The second level adjustment module is used for converting the third voltage of the second sampling interface into a fourth voltage, and transmitting the fourth voltage to the second sampling port;

[0008] The sampling module is used to synchronously collect the second voltage and the fourth voltage, and determine a sampling current based on the second voltage and the fourth voltage.

[0009] It can be understood that by setting the first level adjustment module and the second level adjustment module, the voltage conversion function at the first sampling interface and the second sampling interface to the voltage at the first sampling port and the second sampling port is realized, thereby providing a suitable voltage reference for sampling; at the same time, since the impedance of the first level adjustment module is symmetrical with the impedance of the second level adjustment module, and the impedance of the first sampling port is symmetrical with the impedance of the second sampling port, common-mode interference can be effectively suppressed; that is, the circuit provided by the present invention can filter interference and collect high-precision data without using an operational amplifier, which not only meets the use requirements but also saves costs.

[0010] In an optional embodiment, the first level adjustment module includes a first voltage dividing unit, the second level adjustment module includes a second voltage dividing unit, the first sampling interface, the first voltage dividing unit and the first sampling port are electrically connected in sequence, and the second sampling interface, the second voltage dividing unit and the second sampling port are electrically connected in sequence;

[0011] The first voltage dividing unit is used to convert the first voltage of the first sampling interface into a second voltage, and transmit the second voltage to the first sampling port;

[0012] The second voltage dividing unit is used for converting the third voltage of the second sampling interface into a fourth voltage, and transmitting the fourth voltage to the second sampling port.

[0013] In an optional embodiment, the first voltage-dividing unit includes a first resistor and a second resistor, the second voltage-dividing unit includes a third resistor and a fourth resistor, a power supply, the second resistor, and one end of the first resistor are electrically connected in sequence, the other end of the first resistor is electrically connected to the first sampling interface, the first sampling port is electrically connected between the first resistor and the second resistor, the power supply, the fourth resistor, and one end of the third resistor are electrically connected in sequence, the other end of the third resistor is electrically connected to the second sampling interface, and the second sampling port is electrically connected between the third resistor and the fourth resistor.

[0014] In an optional embodiment, the first level adjustment module further includes a first filtering unit, and the second level adjustment module further includes a second filtering unit, one end of the first filtering unit is electrically connected between the first resistor and the second resistor, and the other end of the first filtering unit is electrically connected to the first sampling port, one end of the second filtering unit is electrically connected between the third resistor and the fourth resistor, and the other end of the second filtering unit is electrically connected to the second sampling port.

[0015] It can be understood that by providing the first filtering unit and the second filtering unit, the differential mode interference in the loop can be effectively filtered out, thereby improving the sampling accuracy and reducing the error.

[0016] In an optional embodiment, the first filtering unit includes a fifth resistor and a first capacitor, the second filtering unit includes a sixth resistor and a second capacitor, one end of the fifth resistor is connected in series with the first capacitor and then grounded, the other end of the fifth resistor is electrically connected between the first resistor and the second resistor, one end of the sixth resistor is connected in series with the second capacitor and then grounded, the other end of the sixth resistor is electrically connected between the third resistor and the fourth resistor, the first sampling port is electrically connected between the fifth resistor and the first capacitor, and the second sampling port is electrically connected between the sixth resistor and the second capacitor.

[0017] In an optional embodiment, the impedance of the first resistor is equal to that of the third resistor, the impedance of the second resistor is equal to that of the fourth resistor, the impedance of the fifth resistor is equal to that of the sixth resistor, and the impedance of the first capacitor is equal to that of the second capacitor.

[0018] In an optional embodiment, the current sampling circuit further includes a filter capacitor, one end of the filter capacitor is electrically connected between the first resistor and the fifth resistor, and the other end of the filter capacitor is electrically connected between the third resistor and the sixth resistor.

[0019] In an optional implementation, the current sampling circuit further includes a first voltage clamping module and a second voltage clamping module, the first voltage clamping module is electrically connected to the first level regulating module, and the second voltage clamping module is electrically connected to the second level regulating module.

[0020] It can be understood that by providing the first voltage clamping module and the second voltage clamping module, the voltages of the first sampling port and the second sampling port can be clamped within a safe range, thereby preventing large currents from damaging the sampling modules.

[0021] In an optional embodiment, the first voltage clamping module includes a first diode and a second diode, the second voltage clamping module includes a third diode and a fourth diode, the power supply is electrically connected to the cathode of the first diode, the anode of the first diode is electrically connected to the cathode of the second diode, the anode of the second diode is grounded, the first level adjustment module is electrically connected between the first diode and the second diode, the power supply is electrically connected to the cathode of the third diode, the anode of the third diode is electrically connected to the cathode of the fourth diode, the anode of the fourth diode is grounded, and the second level adjustment module is electrically connected between the third diode and the fourth diode.

[0022] In a second aspect, an embodiment provides a fan drive system, the fan drive system comprising a drive circuit and a current sampling circuit as described in any one of the aforementioned embodiments, the current sampling circuit being electrically connected to the drive circuit.

[0023] In an optional embodiment, the drive circuit (210) includes an inverter module, the inverter module includes a first bridge arm, a first sampling resistor connected in series with the first bridge arm, a second bridge arm, and a second sampling resistor connected in series with the second bridge arm, the other ends of the first sampling resistor and the second sampling resistor are both grounded, the wind turbine drive system (200) includes two current sampling circuits (100), the first sampling interface (110) of one of the current sampling circuits (100) is electrically connected to one end of the first sampling resistor, the first sampling interface (110) of the other current sampling circuit (100) is electrically connected to one end of the second sampling resistor, and the two current sampling circuits (100) share the same second level adjustment module (140), and are electrically connected to the other ends of the first sampling resistor and the second sampling resistor. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a circuit structure block diagram of the current sampling circuit provided by the present invention.

[0025] Figure 2 A further circuit block diagram of the current sampling circuit provided by the present invention.

[0026] Figure 3 A circuit diagram of a current sampling circuit provided by the present invention.

[0027] Figure 4 This is a circuit structure block diagram of the fan drive system provided by the present invention.

[0028] Figure 5 The present invention is a circuit diagram of a fan drive system.

[0029] Icon: 100-current sampling circuit; 110-first sampling interface; 120-second sampling interface; 130-first level adjustment module; 132-first voltage divider unit; 134-first filtering unit; 140-second level adjustment module; 142-second voltage divider unit; 144-second filtering unit; 150-sampling module; 152-first sampling port; 154-second sampling port; 160-first voltage clamping module; 170-second voltage clamping module; 200-fan drive system; 210-drive circuit. DETAILED DESCRIPTION

[0030] In the prior art, power converters generally adopt the form of digital control, and in power circuits that use current to form closed-loop control and protection, current sampling is the basis for the normal operation of the entire circuit. In power circuits, the most common method for current sampling is to obtain the corresponding current value by detecting the voltage across the sampling resistor connected in series in the main power circuit. However, plagued by common-mode interference, low signal strength and other problems, current sampling uses operational amplifiers to achieve signal amplification and impedance matching functions of current sampling, and in some cases, two or more operational amplifiers need to be cascaded to enhance the above functions. However, high-gain operational amplifiers not only cause large power consumption of the circuit, but also have a high price, which does not meet the demand for the continuous pursuit of low cost for commodities. Therefore, the present invention provides a current sampling circuit and a fan drive system to achieve current and / or voltage acquisition without using an operational amplifier.

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0032] First embodiment

[0033] See also Figure 1 , is a circuit structure block diagram of the current sampling circuit 100 provided by the present invention. The current sampling circuit 100 includes a first sampling interface 110, a second sampling interface 120, a first level adjustment module 130, a second level adjustment module 140, a sampling module 150, a first voltage clamping module 160 and a second voltage clamping module 170. Among them, the sampling module 150 includes a first sampling port 152 and a second sampling port 154, the first sampling interface 110, the first level adjustment module 130 and the first sampling port 152 are electrically connected in sequence, the second sampling interface 120, the second level adjustment module 140 and the second sampling port 154 are electrically connected in sequence, the first voltage clamping module 160 is electrically connected to the first level adjustment module 130, and the second voltage clamping module 170 is electrically connected to the second level adjustment module 140.

[0034] Generally, the most common method of current sampling is to obtain the corresponding current value through the voltage across the sampling resistor connected in series in the main power circuit. Therefore, the first sampling interface 110 and the second sampling interface 120 are respectively located at the two ends of the sampling resistor, and are used to access the voltage across the two ends of the sampling resistor.

[0035] It should be noted that, in order to reduce the loss on the sampling resistor, the resistance range of the sampling resistor is usually between 1 mΩ and 1 Ω.

[0036] The first level adjustment module 130 and the second level adjustment module 140 are used to convert the voltage across the sampling resistor into a voltage that meets the input voltage requirement of the sampling module 150. Specifically, the first level adjustment module 130 is used to convert the first voltage of the first sampling interface 110 into a second voltage, and transmit the second voltage to the first sampling port 152, and the second level adjustment module 140 is used to convert the third voltage of the second sampling interface 120 into a fourth voltage, and transmit the fourth voltage to the second sampling port 154.

[0037] It can be understood that since the sampling resistor is small, the voltage difference between the first sampling interface 110 and the second sampling interface 120 is small, that is, the voltage difference between the first voltage and the third voltage is small, so it is necessary to use the first level adjustment module 130 and the second level adjustment module 140 to adjust the voltage value to achieve the effect of amplifying the voltage difference.

[0038] In addition, it should be noted that the impedance of the first level adjustment module 130 in the present invention is symmetrical with the impedance of the second level adjustment module 140. Since the first level adjustment module 130 and the second level adjustment module 140 have an impedance symmetrical relationship, this relationship can effectively suppress common mode interference, thereby improving the accuracy of current sampling and reducing errors.

[0039] Specifically, see Figure 2 , which is a further circuit block diagram of the current sampling circuit 100 provided by the present invention. The first level adjustment module 130 includes a first voltage dividing unit 132 and a first filtering unit 134, and the second level adjustment module 140 includes a second voltage dividing unit 142 and a second filtering unit 144. Among them, the first sampling interface 110, the first voltage dividing unit 132, the first filtering unit 134 and the first sampling port 152 are electrically connected in sequence, and the second sampling interface 120, the second voltage dividing unit 142, the second filtering unit 144 and the second sampling port 154 are electrically connected in sequence.

[0040] It should be noted that the order of the first voltage divider unit 132 and the first filtering unit 134 can be changed, and the order of the second voltage divider unit 142 and the second filtering unit 144 can also be changed. That is, in another optional implementation, the connection relationship of the current sampling circuit 100 can be: the first sampling interface 110, the first filtering unit 134, the first voltage divider unit 132 and the first sampling port 152 are electrically connected in sequence, and the second sampling interface 120, the second filtering unit 144, the second voltage divider unit 142 and the second sampling port 154 are electrically connected in sequence.

[0041] The first voltage divider unit 132 is used to convert the first voltage of the first sampling interface 110 into a second voltage and transmit the second voltage to the first sampling port 152 ; the second voltage divider unit 142 is used to convert the third voltage of the second sampling interface 120 into a fourth voltage and transmit the fourth voltage to the second sampling port 154 .

[0042] See also Figure 3 , which is a circuit diagram of the current sampling circuit 100 provided by the present invention. Among them, the first voltage dividing unit 132 includes a first resistor R1 and a second resistor R2, the second voltage dividing unit 142 includes a third resistor R3 and a fourth resistor R4, the power supply Vcc, the second resistor R2 and one end of the first resistor R1 are electrically connected in sequence, the other end of the first resistor R1 is electrically connected to the first sampling interface 110, the first sampling port 152 is electrically connected between the first resistor R1 and the second resistor R2, the power supply Vcc, the fourth resistor R4 and one end of the third resistor R3 are electrically connected in sequence, the other end of the third resistor R3 is electrically connected to the second sampling interface 120, and the second sampling port 154 is electrically connected between the third resistor R3 and the fourth resistor R4.

[0043] It can be understood that the first resistor R1 and the second resistor R2 form a voltage divider circuit to achieve conversion from the first voltage to the second voltage; the third resistor R3 and the fourth resistor R4 form another voltage divider circuit to achieve conversion from the third voltage to the fourth voltage.

[0044] One end of the first filter unit 134 is electrically connected between the first resistor R1 and the second resistor R2, and the other end of the first filter unit 134 is electrically connected to the first sampling port 152. One end of the second filter unit 144 is electrically connected between the third resistor R3 and the fourth resistor R4, and the other end of the second filter unit 144 is electrically connected to the second sampling port 154. The first filter unit 134 and the second filter unit 144 are both used to filter interference signals.

[0045] Please continue reading Figure 3 The first filtering unit 134 includes a fifth resistor R5 and a first capacitor C1, the second filtering unit 144 includes a sixth resistor R6 and a second capacitor C2, one end of the fifth resistor R5 is connected in series with the first capacitor C1 and then grounded, the other end of the fifth resistor R5 is electrically connected between the first resistor R1 and the second resistor R2, one end of the sixth resistor R6 is connected in series with the second capacitor C2 and then grounded, the other end of the sixth resistor R6 is electrically connected between the third resistor R3 and the fourth resistor R4, the first sampling port 152 is electrically connected between the fifth resistor R5 and the first capacitor C1, and the second sampling port 154 is electrically connected between the sixth resistor R6 and the second capacitor C2.

[0046] It can be understood that the RC filter circuit composed of the first resistor R1, the fifth resistor R5 and the first capacitor C1, and the RC filter circuit composed of the third resistor R3, the sixth resistor R6 and the second capacitor C2 can effectively filter out the differential mode interference in the circuit, so that the module can receive a more real current signal to improve the accuracy of current sampling and reduce the error of the sampling result.

[0047] It should be noted that in the current sampling circuit 100 provided by the invention, there are two main propagation paths for common-mode interference, one is a first level adjustment module 130 formed by the first resistor R1, the second resistor R2, the fifth resistor R5 and the first capacitor C1, and the other is a second level adjustment module 140 formed by the third resistor R3, the fourth resistor R4, the sixth resistor R6 and the second capacitor C2. Only by making the impedance of the first level adjustment module 130 symmetrical with the impedance of the second level adjustment module 140 can the influence of common-mode interference on signal sampling be effectively suppressed.

[0048] It should also be noted that by making the sum of the impedances of the first resistor R1, the second resistor R2, the fifth resistor R5 and the first capacitor C1 equal to the sum of the impedances of the third resistor R3, the fourth resistor R4, the sixth resistor R6 and the second capacitor C2, the impedance of the first level adjustment module 130 and the impedance of the second level adjustment module 140 can be symmetrical.

[0049] Therefore, in order to make the impedance of the first level adjustment module 130 symmetrical with the impedance of the second level adjustment module 140, in an optional embodiment, the impedance of the first resistor R1 is equal to the impedance of the third resistor R3, the impedance of the second resistor R2 is equal to the impedance of the fourth resistor R4, the impedance of the fifth resistor R5 is equal to the impedance of the sixth resistor R6, and the impedance of the first capacitor C1 is equal to the impedance of the second capacitor C2.

[0050] It should be noted that the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5 and the sixth resistor R6 can be replaced by equivalent resistor networks. For example, if the first resistor R1 is 100Ω, the first resistor R1 can be replaced by two 50Ω resistors connected in series.

[0051] Similarly, the first capacitor C1 and the second capacitor C2 can also be replaced by their equivalent capacitor networks. For example, if the first capacitor C1 is 660 pF, the first capacitor C1 can be replaced by two 1320 pF capacitors connected in parallel.

[0052] In an optional embodiment, the current sampling circuit 100 provided by the present invention further includes a filter capacitor C3, one end of the filter capacitor C3 is electrically connected between the first resistor R1 and the fifth resistor R5, and the other end of the filter capacitor C3 is electrically connected between the third resistor R3 and the sixth resistor R6.

[0053] It can be understood that by providing the filter capacitor C3 , a filter circuit can be formed together with the first resistor R1 and the third resistor R3 to further filter the differential mode interference in the circuit.

[0054] The first voltage clamping module 160 is electrically connected to the first level regulating module 130 , and the second voltage clamping module 170 is electrically connected to the second level regulating module 140 .

[0055] By providing the first voltage clamping module 160 and the second voltage clamping module 170 , the voltages of the first sampling port 152 and the second sampling port 154 can be clamped within a safe range, thereby preventing the sampling module 150 from being damaged by a large current.

[0056] Please continue reading Figure 3 The first voltage clamping module 160 includes a first diode D1 and a second diode D2, the second voltage clamping module 170 includes a third diode D3 and a fourth diode D4, the power supply Vcc is electrically connected to the cathode of the first diode D1, the anode of the first diode D1 is electrically connected to the cathode of the second diode D2, the anode of the second diode D2 is grounded, the first level adjustment module 130 is electrically connected between the first diode D1 and the second diode D2, the power supply Vcc is electrically connected to the cathode of the third diode D3, the anode of the third diode D3 is electrically connected to the cathode of the fourth diode D4, the anode of the fourth diode D4 is grounded, and the second level adjustment module 140 is electrically connected between the third diode D3 and the fourth diode D4.

[0057] The sampling module 150 is used to synchronously collect the second voltage and the fourth voltage, and determine the sampling current based on the second voltage and the fourth voltage.

[0058] In an alternative embodiment, see Figure 3 The sampling module 150 includes a first sampling port 152, a second sampling port 154, a first analog-to-digital conversion unit ADC1, a second analog-to-digital conversion unit ADC2, a first voltage holder S / HA, a second voltage holder S / HB and a controller MCU, and the first sampling port 152, the first analog-to-digital conversion unit ADC1, the first voltage holder S / HA and the controller are electrically connected in sequence, and the second sampling port 154, the second analog-to-digital conversion unit ADC2, the second voltage holder S / HB and the controller MCU are electrically connected in sequence.

[0059] The first analog-to-digital conversion module ADC1 and the second analog-to-digital conversion unit ADC2 are used to convert analog signals into digital signals, and the first voltage holder S / HA and the second voltage holder S / HB are used to maintain the level value of the digital signal to facilitate the controller MCU to collect it.

[0060] In an optional embodiment, the impedance of the loop including the first sampling port 152, the first analog-to-digital conversion unit ADC1 and the first voltage holder S / HA is symmetrical with the impedance of the loop including the second sampling port 154, the second analog-to-digital conversion unit ADC2 and the second voltage holder S / HB, and can also effectively filter the common-mode interference in the loop.

[0061] In an optional implementation, the first sampling port 152, the second sampling port 154, the first analog-to-digital conversion unit ADC1, the second analog-to-digital conversion unit ADC2, the first voltage holder S / HA, the second voltage holder S / HB and the controller MCU can be integrated into one device, such as a single-chip microcomputer. The first sampling port 152 and the second sampling port 154 can be input / output interfaces of the single-chip microcomputer.

[0062] In another optional embodiment, the sampling module 150 may also include only one voltage holder, which is electrically connected to both the first analog-to-digital conversion unit ADC1 and the second analog-to-digital conversion unit ADC2, and is used to simultaneously maintain the level values ​​of the digital signals output by the first analog-to-digital conversion unit ADC1 and the second analog-to-digital conversion unit ADC2.

[0063] It should be noted that the sampling current, the second voltage, and the fourth voltage satisfy the formula:

[0064]

[0065] Wherein, i is the sampling current, u2 is the second voltage, u4 is the fourth voltage, G is a predetermined voltage division coefficient, and Rs is the resistance value of the sampling resistor.

[0066] The voltage division coefficient is related to the resistance values ​​of the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5 and the sixth resistor R6. Once the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5 and the sixth resistor R6 are determined, the voltage division coefficient can be determined. For example, if the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5 and the sixth resistor R6 are equal, then

[0067] Second embodiment

[0068] The present invention also provides a fan drive system 200, see Figure 4 , is a circuit structure block diagram of a fan driving system 200 provided by the present invention. The fan driving system 200 includes a driving circuit 210 and a current sampling circuit 100, and the current sampling circuit 100 is electrically connected to the driving circuit 210.

[0069] In an optional implementation, the fan driving system 200 may include a current sampling circuit 100, and a sampling resistor is connected in parallel to both ends of a power supply Vcc, so that the current sampling circuit 100 can collect input current.

[0070] In another optional embodiment, the fan driving system 200 may include two current sampling circuits 100 (such as Figure 5 As shown), wherein the driving circuit 210 includes an inverter module, the inverter module includes a first bridge arm, a first sampling resistor R connected in series with the first bridge arm s1 , the second bridge arm and the second sampling resistor R connected in series with the second bridge arm s2 , the first sampling resistor R s1 With the second sampling resistor R s2 The other end of each current sampling circuit 100 is grounded, and the first sampling interface 110 of the current sampling circuit 100 is connected to the first sampling resistor R s1 The first sampling interface 110 of the other current sampling circuit 100 is electrically connected to the second sampling resistor R s2 The two current sampling circuits 100 share the same second level adjustment module 140 and are electrically connected to the first sampling resistor R s1 With the second sampling resistor R s2 The other end is electrically connected.

[0071] It can be understood that the current sampling circuit 100 collects the current of the first sampling resistor R s1 The voltage difference between the two ends is used as the U-phase current of the motor, and is collected by another current sampling circuit 100 through the second sampling resistor R s2 The voltage difference between the two ends is used as the V-phase current of the motor, and the W-phase current is calculated using the U-phase current and the V-phase current to achieve current loop regulation during the motor control process.

[0072] It should be noted that the sampling modules 150 of different current sampling circuits 100 can be integrated into the same single-chip microcomputer, that is, one single-chip microcomputer can sample multiple currents at the same time.

[0073] In summary, the current sampling circuit and fan drive system provided by the present invention include a first sampling interface, a second sampling interface, a first level adjustment module, a second level adjustment module and a sampling module, the sampling module includes a first sampling port and a second sampling port, the first sampling interface, the first level adjustment module and the first sampling port are electrically connected in sequence, the second sampling interface, the second level adjustment module and the second sampling port are electrically connected in sequence, the impedance of the first level adjustment module is symmetrical with the impedance of the second level adjustment module, and the impedance of the first sampling port is symmetrical with the impedance of the second sampling port. By setting the first level adjustment module and the second level adjustment module, the voltage conversion function at the first sampling interface and the second sampling interface to the voltage at the first sampling port and the second sampling port is realized, thereby providing a suitable voltage reference for sampling; at the same time, since the impedance of the first level adjustment module is symmetrical with the impedance of the second level adjustment module, and the impedance of the first sampling port is symmetrical with the impedance of the second sampling port, common mode interference can be effectively suppressed; that is, the circuit provided by the present invention can also filter interference and collect high-precision data without using an operational amplifier, which not only meets the use requirements, but also saves costs.

[0074] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A current sampling circuit (100), characterized in that: The current sampling circuit (100) comprises: a first sampling interface (110), a second sampling interface (120), a first level adjustment module (130), a second level adjustment module (140) and a sampling module (150); the sampling module (150) comprises a first sampling port (152) and a second sampling port (154); the first sampling interface (110), the first level adjustment module (130) and the first sampling port (152) are electrically connected in sequence; the second sampling interface (120), the second level adjustment module (140) and the second sampling port (154) are electrically connected in sequence; the impedance of the first level adjustment module (130) is symmetrical to the impedance of the second level adjustment module (140); and the impedance of the first sampling port (152) is symmetrical to the impedance of the second sampling port (154); The first level adjustment module (130) is used to convert the first voltage of the first sampling interface (110) into a second voltage, and transmit the second voltage to the first sampling port (152); The second level adjustment module (140) is used to convert the third voltage of the second sampling interface (120) into a fourth voltage, and transmit the fourth voltage to the second sampling port (154); The sampling module (150) is used to synchronously collect the second voltage and the fourth voltage, and determine the sampling current based on the second voltage and the fourth voltage; wherein the first level adjustment module (130) includes a first voltage dividing unit (132), the second level adjustment module (140) includes a second voltage dividing unit (142), the first sampling interface (110), the first voltage dividing unit (132) and the first sampling port (152) are electrically connected in sequence, and the second sampling interface (120), the second voltage dividing unit (142) and the second sampling port (154) are electrically connected in sequence; The first voltage dividing unit (132) is used to convert the first voltage of the first sampling interface (110) into a second voltage, and transmit the second voltage to the first sampling port (152); The second voltage dividing unit (142) is used for converting the third voltage of the second sampling interface (120) into a fourth voltage, and transmitting the fourth voltage to the second sampling port (154); the first voltage dividing unit (132) comprises a first resistor and a second resistor, the second voltage dividing unit (142) comprises a third resistor and a fourth resistor, a power supply, the second resistor and one end of the first resistor are electrically connected in sequence, the other end of the first resistor is electrically connected to the first sampling interface (110), the first sampling port (152) is electrically connected between the first resistor and the second resistor, the power supply, the fourth resistor and one end of the third resistor are electrically connected in sequence, the other end of the third resistor is electrically connected to the second sampling interface (120), and the second sampling port (154) is electrically connected between the third resistor and the fourth resistor.

2. The current sampling circuit (100) according to claim 1, characterized in that: The first level adjustment module (130) further includes a first filter unit, and the second level adjustment module (140) further includes a second filter unit (144), one end of the first filter unit is electrically connected between the first resistor and the second resistor, and the other end of the first filter unit is electrically connected to the first sampling port (152), one end of the second filter unit (144) is electrically connected between the third resistor and the fourth resistor, and the other end of the second filter unit (144) is electrically connected to the second sampling port (154).

3. The current sampling circuit (100) according to claim 2, characterized in that: The first filtering unit comprises a fifth resistor and a first capacitor, the second filtering unit (144) comprises a sixth resistor and a second capacitor, one end of the fifth resistor is connected in series with the first capacitor and then grounded, the other end of the fifth resistor is electrically connected between the first resistor and the second resistor, one end of the sixth resistor is connected in series with the second capacitor and then grounded, the other end of the sixth resistor is electrically connected between the third resistor and the fourth resistor, the first sampling port (152) is electrically connected between the fifth resistor and the first capacitor, and the second sampling port (154) is electrically connected between the sixth resistor and the second capacitor.

4. The current sampling circuit (100) according to claim 3, characterized in that: The impedance of the first resistor is equal to that of the third resistor, the impedance of the second resistor is equal to that of the fourth resistor, the impedance of the fifth resistor is equal to that of the sixth resistor, and the impedance of the first capacitor is equal to that of the second capacitor.

5. The current sampling circuit (100) according to claim 3, characterized in that: The current sampling circuit (100) further comprises a filter capacitor, one end of which is electrically connected between the first resistor and the fifth resistor, and the other end of which is electrically connected between the third resistor and the sixth resistor.

6. The current sampling circuit (100) according to any one of claims 1 to 5, characterized in that: The current sampling circuit (100) further comprises a first voltage clamping module (160) and a second voltage clamping module (170), wherein the first voltage clamping module (160) is electrically connected to the first level regulating module (130), and the second voltage clamping module (170) is electrically connected to the second level regulating module (140).

7. The current sampling circuit (100) according to claim 6, characterized in that: The first voltage clamping module (160) comprises a first diode and a second diode, the second voltage clamping module (170) comprises a third diode and a fourth diode, the power supply is electrically connected to the cathode of the first diode, the anode of the first diode is electrically connected to the cathode of the second diode, the anode of the second diode is grounded, the first level regulating module (130) is electrically connected between the first diode and the second diode, the power supply is electrically connected to the cathode of the third diode, the anode of the third diode is electrically connected to the cathode of the fourth diode, the anode of the fourth diode is grounded, and the second level regulating module (140) is electrically connected between the third diode and the fourth diode.

8. A fan drive system (200), characterized in that: The fan drive system (200) comprises a drive circuit (210) and a current sampling circuit (100) according to any one of claims 1 to 7, and the current sampling circuit (100) is electrically connected to the drive circuit (210).

9. The fan drive system (200) according to claim 8, characterized in that: The drive circuit (210) comprises an inverter module, the inverter module comprises a first bridge arm, a first sampling resistor connected in series with the first bridge arm, a second bridge arm and a second sampling resistor connected in series with the second bridge arm, the other ends of the first sampling resistor and the second sampling resistor are both grounded, the fan drive system (200) comprises two current sampling circuits (100), the first sampling interface (110) of one of the current sampling circuits (100) is electrically connected to one end of the first sampling resistor, the first sampling interface (110) of the other current sampling circuit (100) is electrically connected to one end of the second sampling resistor, the two current sampling circuits (100) share the same second level adjustment module (140), and are electrically connected to the other ends of the first sampling resistor and the second sampling resistor.

Images