High-precision current sampling module with communication function

Abstract

The utility model discloses a high-precision current sampling module with communication, which relates to the field of sampling, and comprises an equipment working unit used for electrifying a load to work; the Hall current sampling unit is used for detecting the magnitude of current flowing through a load, obtaining first sampling current and feeding back the first sampling current to the control unit; the shunt resistance value adjusting unit is used for receiving the control of the control unit and changing the number of shunts connected into the circuit; the beneficial effects of the utility model are that the amplification factor of the amplifier in the shunt current multiple adjusting unit can be set by configuring feedback resistors with different resistance values through a multiplexer, that is, multiple amplification factors can be realized through one operational amplifier circuit, and current sampling of each current interval can be adapted; the sampling resolution in each current interval is improved, the current sampling precision of the shunt is ensured, and the cost of the current sampling circuit is controlled.

Description

Technical Field

[0001] The utility model relates to the field of sampling, in particular to a high-precision current sampling module with communication. Background Art

[0002] With the frequent occurrence of energy crises in Europe and the growing global consensus on the vigorous development of clean energy, demand for household energy storage has increased overseas. The domestic household energy storage industry has developed rapidly and is committed to the independent research and development of BMS (battery management system) control boards. Low-voltage batteries are a relatively early product, with mature technology. However, a long-standing pain point for low-voltage batteries is their high rated current and wide input current range, resulting in poor full-range current sampling accuracy, which ultimately affects the battery capacity and SOC (remaining charge) calculated by the software. Customers are often extremely concerned about battery capacity when purchasing energy storage products. If they discover a significant deviation between the battery capacity displayed by the system and the product's nominal capacity, customer satisfaction with the product will drop significantly, significantly impacting product sales and reputation.

[0003] The existing solution is to sample the current in multiple segments by designing multiple op amp circuits with different amplification factors. However, due to the limitations of board cost and PCB area, the number of segments is limited. For a wide range of current input, only 2 to 3 segments can be sampled at most. Therefore, although segmented sampling is performed, the current span within each segment is still large, the resolution cannot be effectively improved, and the corresponding current sampling deviation will also be large, which needs to be improved. Utility Model Content

[0004] The purpose of the present utility model is to provide a high-precision current sampling module with communication function, so as to solve the problems raised in the above background technology.

[0005] To achieve the above objectives, the present invention provides the following technical solutions:

[0006] A high-precision current sampling module with communication, comprising:

[0007] Equipment working unit, used to provide power to the load;

[0008] The Hall current sampling unit is used to detect the current flowing through the load, obtain a first sampling current (coarse detection) and feed it back to the control unit;

[0009] The shunt resistance value adjustment unit is used to receive the control of the control unit and change the number of shunts connected to the circuit (adjust the sampling resolution to facilitate sampling);

[0010] The shunt current multiple adjustment unit is used to receive control from the control unit, change the sampled current multiple, detect the current flowing through the load, obtain a second sampled current (fine detection) and feed it back to the control unit;

[0011] A control unit, configured to control the operating states of the shunt resistance adjustment unit and the shunt current multiple adjustment unit based on the magnitude of the first sampled current (i.e., to change the number of shunts connected to the circuit and change the sampled current multiple);

[0012] CAN communication unit, used to establish communication between the control unit and the host computer;

[0013] The equipment working unit is connected to the shunt resistance adjustment unit, the shunt resistance adjustment unit is connected to the Hall current sampling unit and the shunt current multiple adjustment unit, the Hall current sampling unit is connected to the control unit, the shunt current multiple adjustment unit is connected to the control unit, and the control unit is connected to the CAN communication unit.

[0014] As a further solution of the present invention: the device working unit includes a battery BAT, a load LOAD, and the positive electrode of the battery BAT, the load LOAD, a switch, a shunt resistance adjustment unit, a Hall current sampling unit, and the negative electrode of the battery BAT form a circuit.

[0015] As a further solution of the present invention: the Hall current sampling unit includes a Hall sensor U2, the IP+ pin of the Hall sensor U2 is connected to the shunt resistance adjustment unit, the IP- pin of the Hall sensor U2 is connected to the device working unit, the VOUT pin of the Hall sensor U2 is connected to one end of the resistor R12, the other end of the resistor R12 is connected to one end of the capacitor C2 and the control unit, and the other end of the capacitor C2 is grounded.

[0016] As a further solution of the present utility model: the shunt resistance adjustment unit includes a MOS transistor Q1, a MOS transistor Q2, a shunt R1_1, and a shunt R1_2. The D pole of the MOS transistor Q1 is connected to one end of the shunt R1_2, and a device working module. The S pole of the MOS transistor Q1 is connected to the D pole of the MOS transistor Q2, the S pole of the MOS transistor Q2 is connected to one end of the shunt R1_1, the other end of the shunt R1_1 is connected to the other end of the shunt R1_2, and a Hall current sampling unit. The G pole of the MOS transistor Q1 is connected to the control unit, and the G pole of the MOS transistor Q2 is connected to the control unit.

[0017] As a further solution of the present invention: the shunt current multiplexer adjustment unit includes a multiplexer U1, a multiplexer U3, and an amplifier U7. The inverting end of the amplifier U7 is connected to one end of the resistor R2 and the X pin of the multiplexer U1. The other end of the resistor R2 is connected to the shunt resistance adjustment unit. The non-inverting end of the amplifier U7 is connected to one end of the resistor R3 and the X pin of the multiplexer U3. The other end of the resistor R3 is connected to the shunt resistance adjustment unit. The output end of the amplifier U7 is connected to the control unit. The A, B, and C pins of the multiplexer U1 are connected to the control unit. The X0, X1, X2, X3, and X 4. The X5, X6, and X7 pins are connected to the output end of the amplifier U7 through a resistor of different resistance values. The A, B, and C pins of the multiplexer U3 are connected to the control unit. The X0, X1, X2, X3, X4, X5, X6, and X7 pins of the multiplexer U3 are connected to the 3.3V voltage through a resistor string of different resistance values. The resistor string consists of two resistors in series. The resistance value of the resistor string on the X0, X1, X2, X3, X4, X5, X6, and X7 pins of the multiplexer U3 is twice the resistance value of the corresponding resistor on the X0, X1, X2, X3, X4, X5, X6, and X7 pins of the multiplexer U1.

[0018] As a further solution of the present utility model: the control unit includes a control chip U4, the model of the control chip U4 is, the PC0, PC1, PC2, and ADC-IN0 pins of the control chip U4 are connected to the shunt current multiplier adjustment unit, the ADC-IN1 pin of the control chip U4 is connected to the Hall current sampling unit, the PC3 and PC4 pins of the control chip U4 are connected to the shunt resistance adjustment unit, and the CAN-TX and CAN-RX pins of the control chip U4 are connected to the CAN communication unit.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: in the present invention, the amplification factor of the amplifier in the shunt current multiplier adjustment unit can be set by configuring feedback resistors of different resistance values ​​through a multiplexer, that is, a variety of amplification factors can be achieved through one operational amplifier circuit, which is adapted to the current sampling of each current interval, thereby improving the sampling resolution within each current interval, ensuring the accuracy of the shunt current sampling, and controlling the cost of the current sampling circuit; when the shunt resistance value adjustment unit is working, it will first detect the current value through the Hall current sampling unit and give it to the control unit, and then the control unit will determine the current interval to which the current value belongs, and set The corresponding amplification factor and the shunt resistance value required to be connected to the circuit are calculated in the shunt resistance adjustment unit, and then the current value collected by the shunt current multiplier adjustment is read, thereby avoiding the step of determining the op amp amplification factor step by step in the algorithm and improving the speed of current sampling; the shunt current multiplier adjustment adds a bias circuit, and the bias resistor can be synchronously adjusted according to the change of the feedback resistor to ensure that the bias voltage is always approximately equal to 1 / 2 of the reference voltage, which can realize the current sampling circuit to sample the battery charging current and discharging current. The shunt resistance adjustment can improve the sampling accuracy of small currents when sampling small currents and reduce the power consumption on the shunt when sampling large currents. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The circuit diagram of a high-precision current sampling module with communication. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0022] See also Figure 1 , a high-precision current sampling module with communication, including:

[0023] Equipment working unit, used to provide power to the load;

[0024] The Hall current sampling unit is used to detect the current flowing through the load, obtain a first sampling current (coarse detection) and feed it back to the control unit;

[0025] The shunt resistance value adjustment unit is used to receive the control of the control unit and change the number of shunts connected to the circuit (adjust the sampling resolution to facilitate sampling);

[0026] The shunt current multiple adjustment unit is used to receive control from the control unit, change the sampled current multiple, detect the current flowing through the load, obtain a second sampled current (fine detection) and feed it back to the control unit;

[0027] A control unit, configured to control the operating states of the shunt resistance adjustment unit and the shunt current multiple adjustment unit based on the magnitude of the first sampled current (i.e., to change the number of shunts connected to the circuit and change the sampled current multiple);

[0028] CAN communication unit, used to establish communication between the control unit and the host computer;

[0029] The equipment working unit is connected to the shunt resistance adjustment unit, the shunt resistance adjustment unit is connected to the Hall current sampling unit and the shunt current multiple adjustment unit, the Hall current sampling unit is connected to the control unit, the shunt current multiple adjustment unit is connected to the control unit, and the control unit is connected to the CAN communication unit.

[0030] In this example: See Figure 1 The working unit of the device includes a battery BAT and a load LOAD. The positive electrode of the battery BAT, the load LOAD, a switch, a shunt resistance adjustment unit, a Hall current sampling unit, and the negative electrode of the battery BAT form a circuit.

[0031] After the switch is closed, the circuit is successfully established and the load LOAD is energized and starts working.

[0032] In this example: See Figure 1 The Hall current sampling unit includes a Hall sensor U2, the IP+ pin of the Hall sensor U2 is connected to the shunt resistance adjustment unit, the IP- pin of the Hall sensor U2 is connected to the device working unit, the VOUT pin of the Hall sensor U2 is connected to one end of the resistor R12, the other end of the resistor R12 is connected to one end of the capacitor C2 and the control unit, and the other end of the capacitor C2 is grounded.

[0033] The Hall sensor U2 can collect the current in the entire range of the battery (coarse detection) and transmit the collected data to the control unit.

[0034] In this example: See Figure 1 The shunt resistance adjustment unit includes a MOS transistor Q1, a MOS transistor Q2, a shunt R1_1, and a shunt R1_2. The D pole of the MOS transistor Q1 is connected to one end of the shunt R1_2, and a device working module. The S pole of the MOS transistor Q1 is connected to the D pole of the MOS transistor Q2. The S pole of the MOS transistor Q2 is connected to one end of the shunt R1_1. The other end of the shunt R1_1 is connected to the other end of the shunt R1_2, and a Hall current sampling unit. The G pole of the MOS transistor Q1 is connected to the control unit, and the G pole of the MOS transistor Q2 is connected to the control unit.

[0035] To address power consumption and heat generation issues when sampling high currents, as well as improving sampling accuracy when sampling low currents, the circuit features two shunts, R1_1 = R1_2. R1_2 is connected directly in series in the current loop, while R1_1 is connected in parallel to R1_2 via a pair of back-to-back MOS transistors, Q1 and Q2. Because MOS transistors have body diodes, two MOS transistors are designed to control the parallel connection and disconnection of shunts R1_1 and R1_2 during battery charging and discharging, respectively. Before current sampling, both MOS transistors Q1 and Q2 are closed. The control unit then determines the current value based on the current value collected by the Hall current sampling unit and controls whether MOS transistors Q1 and Q2 are closed or disconnected. When the current is small, Q1 and Q2 are controlled to be disconnected, the shunt resistance is increased, and the sampling accuracy of the small current is improved. When the current is large, Q1 and Q2 are controlled to be closed, R1_1 and R1_2 are connected in parallel, the shunt resistance is reduced, and the sampling range for large current is increased. At the same time, the power consumption of the shunt is reduced and the temperature rise of the shunt during continuous sampling is improved.

[0036] In this example: See Figure 1 The shunt current multiple adjustment unit includes a multiplexer U1, a multiplexer U3, and an amplifier U7. The inverting end of the amplifier U7 is connected to one end of the resistor R2 and the X pin of the multiplexer U1, and the other end of the resistor R2 is connected to the shunt resistance adjustment unit. The non-inverting end of the amplifier U7 is connected to one end of the resistor R3 and the X pin of the multiplexer U3. The other end of the resistor R3 is connected to the shunt resistance adjustment unit. The output end of the amplifier U7 is connected to the control unit. The A, B, and C pins of the multiplexer U1 are connected to the control unit. X0, X1, X2, X3, X4, X5, and X6 of the multiplexer U1 are connected to the control unit. The X0, X1, X2, X3, X4, X5, X6, and X7 pins of the multiplexer U3 are connected to the output end of the amplifier U7 through a resistor of different resistance values, respectively. The A, B, and C pins of the multiplexer U3 are connected to the control unit. The X0, X1, X2, X3, X4, X5, X6, and X7 pins of the multiplexer U3 are connected to the 3.3V voltage through a resistor string of different resistance values, respectively. The resistor string consists of two resistors in series. The resistance values ​​of the resistor strings on the X0, X1, X2, X3, X4, X5, X6, and X7 pins of the multiplexer U3 are twice the resistance values ​​of the corresponding resistors on the X0, X1, X2, X3, X4, X5, X6, and X7 pins of the multiplexer U1.

[0037] The shunt current multiplier adjustment unit amplifies and samples the voltage generated by the current on the shunt through the operational amplifier. In the circuit, R2 = R3. In addition, the feedback resistor is equal to the bias resistor, that is, Rn = Rn+9 = Rn+17. For example, R4 = R13 = R21. The shunt sampling circuit outputs V CURRENT_AD_SHUNT =-Rn / R2*V SHUNT +V REF_3V3*(R2+Rn) / {R2+(Rn+9)+(Rn+17)},V SHUNT is the voltage value generated by the current passing through the shunt, and VREF_3V3 is the reference voltage value.

[0038] The feedback resistor Rn can be selected by controlling the multiplexers U1 and U3 through the control unit to realize the control of different amplification factors of the operational amplifier. According to the current range of the entire system and the number of multiplexer channels, the current is divided into several sections for sampling. For example, if the system current range is 0-100A, 0-10A can be divided into the first section, 10-20A can be divided into the second section, and so on. After the current sampling is divided into multiple sections, the operational amplifier feedback resistor value of each section is matched according to the operational amplifier calculation formula mentioned above and the maximum current sampling value in each section, and the amplification factor suitable for each current sampling interval is set. Similarly, the bias resistors (Rn+9)+(Rn+17) are selected through the MCU-controlled multiplexer and correspond one-to-one with the feedback resistors, ensuring that the bias resistor value is always twice the feedback resistor, that is, (Rn+9)+(Rn+17)=2Rn. Since Rn>>R2, the op amp resistor reference is ≈VREF_3V3 / 2, which satisfies the current sampling circuit's ability to sample a wide range of battery currents during charging and discharging.

[0039] In this example: See Figure 1 The control unit includes a control chip U4. The model of the control chip U4 is: the PC0, PC1, PC2, and ADC-IN0 pins of the control chip U4 are connected to the shunt current multiplier adjustment unit, the ADC-IN1 pin of the control chip U4 is connected to the Hall current sampling unit, the PC3 and PC4 pins of the control chip U4 are connected to the shunt resistance adjustment unit, and the CAN-TX and CAN-RX pins of the control chip U4 are connected to the CAN communication unit.

[0040] The control chip U4 reads the AD values ​​output by the shunt current multiplier adjustment unit and the Hall current sampling unit. It then converts the data into CAN bus data via the CAN chip (U5 in the attached figure) and transmits it to the main control chip on the BMS board inside the battery. This minimizes voltage signal attenuation during transmission. The CAN bus has strong anti-interference capabilities and a long transmission distance, ensuring the accuracy of the current sampling module while freeing the module's installation location within the battery from any restrictions on its distance from the BMS board, greatly increasing the module's installation flexibility. Furthermore, the module is compatible with different projects, helping to shorten project development cycles and improve project development progress.

[0041] In summary, 1. The existing scheme of sampling current in multiple segments by designing multiple operational amplifier circuits with different amplification factors is limited by the cost of the board and the area of ​​the PCB board. The number of segments is limited. For a wide range of current input, it can only be sampled in 2 to 3 segments at most. Therefore, although segmented sampling is performed, the span of the current in each segment interval is still large, the resolution cannot be effectively improved, and the corresponding current sampling deviation will also be large. The present invention adds a multiplexer and combines feedback resistors of different resistance values ​​on the basis of an operational amplifier circuit to realize the configuration of multiple amplification factors of a single operational amplifier circuit (shunt current multiplier adjustment unit). When sampling a wide range of current, batch segmented sampling can be realized, so that the current span in each segment interval is smaller, the resolution is higher, and the cost will not increase significantly.

[0042] 2. The existing method of converting the voltage value generated by the current on the SHUNT into a digital signal through an op amp and then a FPGA conversion circuit and then transmitting it to the MCU can effectively reduce the deviation caused by signal attenuation when the signal is transmitted over a long distance on the PCB. However, the error at the signal sampling source is still large, so it cannot effectively improve the accuracy of current sampling. In addition, the digital signal is also easily interfered with by other functional modules during long-distance transmission. The shunt current multiplier adjustment unit of the utility model performs batch segmented sampling of a wide range of currents, reducing the current span within each segmented interval, and then matching different segmented intervals with op amp circuits with different amplification factors to improve the sampling resolution of each sampling current interval, ensuring the full range of current sampling accuracy. In addition, the shunt resistance adjustment unit of the utility model can adjust the shunt resistance, taking into account the accuracy of small current sampling and the power consumption and temperature rise problems during continuous sampling of large currents. In addition, the utility model adopts a modular design, which transmits the signal output by the current sampling circuit to the MCU nearby, and then converts it into CAN bus data and transmits it to the control chip of the main control board, which can improve the signal's anti-interference ability and increase the transmission distance.

[0043] 3. The existing method of collecting current values ​​through Hall sensors, designing an operational amplifier in the current signal collection circuit, and configuring feedback resistors of different resistance values ​​through a multiplexer to set different amplification factors of the operational amplifier to collect currents of different segments can effectively improve the sampling accuracy of wide-range currents, but the sampling speed is slow because this method needs to use an algorithm to determine the amplification factor suitable for collecting the current step by step, which will take time when collecting current. For safety reasons, BMS has high requirements for current collection speed, and this solution cannot meet the requirements in terms of collection speed. The shunt current multiplier adjustment unit of the utility model samples the current through an operational amplifier circuit with adjustable amplification factor and controllable bias, and also adds a full-range Hall current sampling unit. Since the Hall current sampling accuracy is lower than that of the shunt, the current current value is first sampled by the Hall sensor and transmitted to the control chip. Then the control chip directly configures the corresponding amplification factor according to the pre-set current segment interval, saving the time of step-by-step matching through the algorithm and improving the speed of current sampling. In addition, the shunt current multiplier adjustment unit in the utility model adds a bias circuit. When configuring the operational amplifier amplification factor, the feedback resistor and the bias resistor can be synchronously matched, always ensuring that the bias voltage of the shunt sampling circuit is basically equal to 1 / 2 of the reference voltage, thereby realizing the current sampling circuit sampling the battery charging and discharging current.

[0044] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered in all respects as exemplary and non-restrictive.

[0045] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A high-precision current sampling module with communication, characterized in that: The high-precision current sampling module with communication includes: Equipment working unit, used to provide power to the load; The Hall current sampling unit is used to detect the magnitude of the current flowing through the load, obtain a first sampling current and feed it back to the control unit; A shunt resistance adjustment unit, configured to receive control from the control unit and change the number of shunts connected to the circuit; The shunt current multiple adjustment unit is used to receive control from the control unit, change the sampled current multiple, detect the current flowing through the load, obtain a second sampled current and feed it back to the control unit; A control unit, configured to control the operating states of the shunt resistance value adjustment unit and the shunt current multiple adjustment unit based on the magnitude of the first sampling current; CAN communication unit, used to establish communication between the control unit and the host computer; The equipment working unit is connected to the shunt resistance adjustment unit, the shunt resistance adjustment unit is connected to the Hall current sampling unit and the shunt current multiple adjustment unit, the Hall current sampling unit is connected to the control unit, the shunt current multiple adjustment unit is connected to the control unit, and the control unit is connected to the CAN communication unit.

2. The high-precision current sampling module with communication according to claim 1, characterized in that: The working unit of the device includes a battery BAT and a load LOAD. The positive electrode of the battery BAT, the load LOAD, a switch, a shunt resistance adjustment unit, a Hall current sampling unit, and the negative electrode of the battery BAT form a circuit.

3. The high-precision current sampling module with communication according to claim 1, characterized in that: The Hall current sampling unit includes a Hall sensor U2, the IP+ pin of the Hall sensor U2 is connected to the shunt resistance adjustment unit, the IP- pin of the Hall sensor U2 is connected to the device working unit, the VOUT pin of the Hall sensor U2 is connected to one end of the resistor R12, the other end of the resistor R12 is connected to one end of the capacitor C2 and the control unit, and the other end of the capacitor C2 is grounded.

4. The high-precision current sampling module with communication according to claim 1, characterized in that: The shunt resistance adjustment unit includes a MOS transistor Q1, a MOS transistor Q2, a shunt R1_1, and a shunt R1_2. The D pole of the MOS transistor Q1 is connected to one end of the shunt R1_2, a device working module, the S pole of the MOS transistor Q1 is connected to the D pole of the MOS transistor Q2, the S pole of the MOS transistor Q2 is connected to one end of the shunt R1_1, the other end of the shunt R1_1 is connected to the other end of the shunt R1_2, a Hall current sampling unit, the G pole of the MOS transistor Q1 is connected to the control unit, and the G pole of the MOS transistor Q2 is connected to the control unit.

5. The high-precision current sampling module with communication according to claim 1, characterized in that: The shunt current multiple adjustment unit includes a multiplexer U1, a multiplexer U3, and an amplifier U7. The inverting end of the amplifier U7 is connected to one end of the resistor R2 and the X pin of the multiplexer U1. The other end of the resistor R2 is connected to the shunt resistance adjustment unit. The non-inverting end of the amplifier U7 is connected to one end of the resistor R3 and the X pin of the multiplexer U3. The other end of the resistor R3 is connected to the shunt resistance adjustment unit. The output end of the amplifier U7 is connected to the control unit. The A, B, and C pins of the multiplexer U1 are connected to the control unit. The X0, X1, X2, X3, X4, X5, X6, The X7 pin is connected to the output end of the amplifier U7 through a resistor of different resistance value. The A, B, and C pins of the multiplexer U3 are connected to the control unit. The X0, X1, X2, X3, X4, X5, X6, and X7 pins of the multiplexer U3 are connected to the 3.3V voltage through a resistor string of different resistance value. The resistor string is composed of two resistors in series. The resistance value of the resistor string on the X0, X1, X2, X3, X4, X5, X6, and X7 pins of the multiplexer U3 is twice the resistance value of the corresponding resistor on the X0, X1, X2, X3, X4, X5, X6, and X7 pins of the multiplexer U1.

6. The high-precision current sampling module with communication according to any one of claims 1 to 5, characterized in that: The control unit includes a control chip U4. The model of the control chip U4 is: PC0, PC1, PC2, and ADC-IN0 pins of the control chip U4 are connected to the shunt current multiplier adjustment unit; the ADC-IN1 pin of the control chip U4 is connected to the Hall current sampling unit; the PC3 and PC4 pins of the control chip U4 are connected to the shunt resistance adjustment unit; and the CAN-TX and CAN-RX pins of the control chip U4 are connected to the CAN communication unit.

Images