Current sampling circuit, battery management system and battery equipment

Abstract

A current sampling circuit comprises a voltage conversion unit, an operational amplifier, a micro-control unit and a power supply circuit, the voltage conversion unit is connected to a battery module and electrically connected with a mains supply through a first line and a second line, and a current sensor is arranged on the first line. And the voltage of a first reference point on the first line is a first reference voltage Vref1. The positive input end of the operational amplifier is electrically connected to the first reference point, the reverse input end of the operational amplifier is electrically connected to the first line, the output end of the operational amplifier is electrically connected to the micro-control unit, and the power circuit is electrically connected with the micro-control unit and the battery module and generates power supply voltage VDD for supplying power to the micro-control unit. The power supply circuit is electrically connected to a first reference point and a first reference ground, a grounding pin of the micro-control unit is electrically connected to the first reference ground, the voltage of the first reference ground is defined as a second reference voltage Vref2, and Vref1 is greater than Vref2 and less than VDD.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of current sampling technology, and in particular to a current sampling circuit, a battery management system and a battery device. Background Art

[0002] The battery device is connected to the mains via the live wire and the neutral wire. The DC power of the battery device is converted into AC power and transmitted to the mains via the live wire and the neutral wire. Alternatively, the AC power of the mains is transmitted via the live wire and the neutral wire and converted into DC power to charge the battery device. Among them, the current on the live wire and the neutral wire is AC current, which generally needs to be sampled for algorithm control and power calculation. Summary of the invention

[0003] The embodiments of the present application provide a current sampling circuit, a battery management system and a battery device, which can improve sampling accuracy, have a simple circuit structure and low cost.

[0004] In a first aspect, an embodiment of the present application provides a current sampling circuit, comprising: a voltage conversion unit, configured such that one side of the voltage conversion unit is electrically connected to a battery module, and the other side of the voltage conversion unit is electrically connected to the mains; a first circuit and a second circuit electrically connected to the voltage conversion unit, the first circuit and the second circuit being configured to be electrically connected to the mains, a current sensor being arranged on the first circuit, the first circuit being electrically connected to a first reference point, and the voltage of the first reference point being defined as a first reference voltage Vref1; an operational amplifier and a microcontroller unit, the positive input terminal of the operational amplifier being electrically connected to the first reference point, the reverse input terminal of the operational amplifier being electrically connected to the first circuit, and the output terminal of the operational amplifier being electrically connected to the microcontroller unit; a power supply circuit electrically connected to the microcontroller unit, configured to be electrically connected to the battery module and to generate a power supply voltage VDD for powering the microcontroller unit, the power supply circuit being electrically connected to the first reference point and a first reference ground, the ground pin of the microcontroller unit being electrically connected to the first reference ground, and the voltage of the first reference ground being defined as a second reference voltage Vref2, wherein Vref2<Vref1<VDD.

[0005] The current sensor samples the current flowing through the first circuit and converts it into a sampling voltage relative to the first reference voltage Vref1. The operational amplifier compares the sampling voltage with the first reference voltage Vref1 and outputs a comparison signal to the microcontroller unit. The microcontroller unit can determine the current flowing through the first circuit according to the comparison signal to achieve current sampling. In addition, the power supply circuit electrically connected to the battery module can generate a power supply voltage VDD for the microcontroller unit, and is electrically connected to the first reference point and the first reference ground, while the ground pin of the microcontroller unit is electrically connected to the first reference ground, and the voltage of the first reference ground is the second reference voltage Vref2, wherein the voltage magnitude relationship among the first reference voltage Vref1, the second reference voltage Vref2 and the power supply voltage VDD is Vref2<Vref1<VDD.

[0006] Therefore, the second reference voltage Vref2 of the microcontroller unit is less than the first reference voltage Vref1 on the first circuit, and both are less than the power supply voltage VDD of the microcontroller unit, so that the microcontroller unit can directly sample the current of the first circuit without setting an isolation circuit between the first circuit and the operational amplifier, thereby reducing current conversion, improving sampling accuracy, and simplifying the circuit structure, thereby reducing circuit cost.

[0007] In some embodiments, the difference between the first reference voltage Vref1 and the second reference voltage Vref2 is less than or equal to a preset threshold.

[0008] Therefore, by limiting the difference between the first reference voltage Vref1 and the second reference voltage Vref2, it can be reliably ensured that the sampling voltage is a voltage smaller than the microprocessing unit, thereby ensuring that the microprocessing unit can directly receive and process the sampling voltage without isolation conversion, thereby improving sampling accuracy and making reception more reliable.

[0009] In some embodiments of the present application, the current sensor is a first current sensor, and the operational amplifier is a first operational amplifier. One end of the first current sensor is electrically connected to the voltage conversion unit and the inverting input end of the first operational amplifier, and the other end of the first current sensor is electrically connected to the first reference point, or one end of the first current sensor is electrically connected to the voltage conversion unit and the first reference point, and the other end of the first current sensor is electrically connected to the inverting input end of the first operational amplifier.

[0010] In some embodiments of the present application, the current sensor is two second current sensors, and the operational amplifier is two second operational amplifiers. One end of one second current sensor is electrically connected to the voltage conversion unit and the inverting input end of the first operational amplifier, the other end of one second current sensor is electrically connected to the first reference point, one end of another second current sensor is electrically connected to the first reference point, and the other end of another second current sensor is electrically connected to the inverting input end of another first operational amplifier.

[0011] In the embodiment of the present application, two second current sensors are used to respectively collect the current flowing through the first line. The current collected by the second current sensor close to the voltage conversion unit is closer to the real current and is used for current collection, while the current collected by the second current sensor close to the AC power is smoother and more accurate when used for power calculation.

[0012] In some embodiments of the present application, the power supply circuit includes: a flyback power supply unit and a linear regulator electrically connected to the flyback power supply unit. The flyback power supply unit is configured to be electrically connected to the battery module, the input end of the linear regulator is electrically connected to the output end of the flyback power supply unit, the ground end of the linear regulator is electrically connected to the first reference ground, and the output end of the linear regulator is electrically connected to the power pin of the micro control unit.

[0013] The flyback power supply unit can convert the first DC voltage output by the battery module into an AC voltage by controlling the on and off time of the switch device, and then rectify the AC voltage to finally output a second DC voltage. The second DC voltage will fluctuate, so a linear regulator is used to stabilize the second DC voltage and output a stable power supply voltage VDD to ensure the reliable operation of the microcontroller.

[0014] In some embodiments of the present application, the power supply circuit includes a reference voltage generating unit electrically connected to the output end of the linear regulator. The reference voltage generating unit includes: a first resistor, a reference voltage chip and a first capacitor, one end of the first resistor is electrically connected to the output end of the linear regulator, the other end of the first resistor is electrically connected to the cathode of the reference voltage chip, the reference end of the reference voltage chip, the first reference point and one end of the first capacitor, and the anode of the reference voltage chip is electrically connected to the other end of the first capacitor and the first reference ground.

[0015] The reference voltage generating unit can generate a more stable and more accurate reference voltage. Therefore, by using the reference voltage generating unit to convert the power supply voltage VDD into the first reference voltage Vref1, the first reference voltage Vref1 can be made more accurate and stable.

[0016] In some embodiments of the present application, the flyback power supply unit includes a transformer, a switch unit, a drive unit, and a filter unit. The transformer includes a primary winding and a secondary winding coupled to each other, the switch unit is configured to be electrically connected between the battery module and the second reference ground, the output end of the drive unit is electrically connected to the control end of the switch unit, the ground end of the switch unit and the ground end of the drive unit are both electrically connected to the second reference ground, the filter unit is electrically connected between the output end of the secondary winding and the input end of the linear regulator, and the ground end of the secondary winding and the ground end of the filter unit are both electrically connected to the first reference ground.

[0017] In some embodiments of the present application, the inductor and the second capacitor are provided on the first circuit and connected in series with the current sensor, one end of the second capacitor is electrically connected to the first circuit and the first reference point, and the other end of the second capacitor is electrically connected to the second circuit.

[0018] In the embodiment of the present application, the inductor is used to filter the current and boost the voltage output from the mains to the battery module to achieve power factor correction and improve the power factor. At the same time, the second capacitor is also used to smooth the mains voltage and reduce noise and interference on the first line or the second line.

[0019] In a second aspect, an embodiment of the present application provides a battery management system, comprising the current sampling circuit as described above.

[0020] In a third aspect, an embodiment of the present application provides a battery device, including a battery module and a battery management system as described above, wherein the battery module is electrically connected to the battery management system.

[0021] Compared with the prior art, the current sampling circuit of the embodiment of the present application includes a voltage conversion unit, a first circuit, a second circuit, an operational amplifier, a micro control unit and a power supply circuit, wherein the voltage conversion unit is connected between the battery module and the mains, and the voltage conversion unit is electrically connected to the mains through the first circuit and the second circuit, a current sensor is provided on the first circuit, and the voltage of the first reference point on the first circuit is the first reference voltage Vref1. The current sensor samples the current flowing through the first circuit and converts it into a sampling voltage relative to the first reference voltage Vref1, the operational amplifier compares the sampling voltage with the first reference voltage Vref1, and outputs a comparison signal to the micro control unit, and the micro control unit can determine the AC current flowing through the first circuit according to the comparison signal to achieve current sampling. Furthermore, the power supply circuit electrically connected to the battery module can generate a power supply voltage VDD for powering the micro control unit, and is electrically connected to a first reference point and a first reference ground, and a ground pin of the micro control unit is electrically connected to the first reference ground, and the voltage of the first reference ground is the second reference voltage Vref2, wherein the voltage magnitude relationship among the first reference voltage Vref1, the second reference voltage Vref2 and the power supply voltage VDD is Vref2<Vref1<VDD.

[0022] Therefore, the second reference voltage Vref2 of the microcontroller unit is less than the first reference voltage Vref1 on the first circuit, and both are less than the power supply voltage VDD of the microcontroller unit, so that the microcontroller unit can directly sample the current of the first circuit without setting an isolation circuit between the first circuit and the operational amplifier, thereby reducing current conversion, improving sampling accuracy, and simplifying the circuit structure, thereby reducing circuit cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] One or more embodiments are exemplarily described by the figures in the corresponding drawings, and these exemplary descriptions are not intended to limit the embodiments. Elements with the same reference numerals in the drawings represent similar elements.

[0024] Figure 1 It is a structural schematic diagram of one of the power supply systems in the related art;

[0025] Figure 2 It is a structural schematic diagram of one of the power supply systems in the related art;

[0026] Figure 3 is a schematic diagram of the structure of a voltage conversion unit provided in an embodiment of the present application;

[0027] Figure 4 is a structural schematic diagram of one of the current sampling circuits provided in an embodiment of the present application;

[0028] Figure 5is a structural schematic diagram of one of the current sampling circuits provided in an embodiment of the present application;

[0029] Figure 6 is a structural schematic diagram of one of the current sampling circuits provided in an embodiment of the present application;

[0030] Figure 7 is a schematic diagram of the structure of a power supply circuit provided in an embodiment of the present application;

[0031] Figure 8 is a schematic diagram of the structure of a power supply circuit provided in an embodiment of the present application;

[0032] Fig. 9 is a schematic diagram of the structure of a power supply circuit provided in an embodiment of the present application;

[0033] Fig.10 It is a circuit structure diagram of one of the power supply circuits provided in the embodiments of the present application. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and in detail in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0035] In the present application, when an element is expressed as being “connected to” another element, it may be directly connected to the other element, or one or more intervening elements may be present therebetween.

[0036] In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as there is no structural conflict between them.

[0037] The battery device of the present application can be applied to a variety of charging and discharging scenarios, such as industrial and commercial, power stations, household, charging stations, etc. The battery device of the present application can be a grid-connected energy storage system, which is connected to the mains. The battery device can release the stored energy and supply it to the mains during the peak period of power demand, so as to achieve mains peak regulation and energy balance.

[0038] Figure 1 It is a structural diagram of the power supply system in the related technology, such as Figure 1As shown, the power supply system includes a battery device 100 and a mains power 200, and the mains power 200 is an external AC mains power. The battery device 100 of the embodiment of the present application includes a battery module 10 and a battery management system 20. The battery module 10 includes a plurality of parallel, series or mixed battery cells for storing and providing electrical energy, and the mixed connection includes series and parallel. The battery module 10 and the battery management system 20 (Battery Management System, BMS) together constitute a battery pack. The BMS manages the charging and / or discharging of the battery module 10, and is also used to monitor, manage and protect the performance and safety of the battery module 10.

[0039] The battery management system 20 includes a voltage conversion unit 201, one side of the voltage conversion unit 201 is connected to the battery module 10, and the other side of the voltage conversion unit 201 is electrically connected to the mains 200. Specifically, the voltage conversion unit 201 is electrically connected to the mains 200 via a first line and a second line, that is, the DC side of the voltage conversion unit 201 is electrically connected to the battery module 10, and the AC side of the voltage conversion unit 201 is electrically connected to the mains 200 via the first line and the second line.

[0040] The first circuit and the second circuit are the live wire and the neutral wire. If the first circuit is the live wire, the second circuit is the neutral wire. If the first circuit is the neutral wire, the second circuit is the live wire.

[0041] In some embodiments, the voltage conversion unit 201 is an inverter circuit, and when the battery module 10 is discharged, the AC connection end of the voltage conversion unit 201 is its output end. The voltage conversion unit 201 converts the DC power of the battery module 10 into AC power and outputs it to the mains 200.

[0042] In some embodiments, Figure 2 As shown, when the voltage conversion unit 201 is an inverter circuit, the voltage conversion unit 201 converts the direct current of the battery module 10 into alternating current, and the alternating current is output to the load 300 .

[0043] For other embodiments, please refer to Figure 1 The voltage conversion unit 201 is a power factor correction circuit (Power Factor Correct Ci rcuit, PFC circuit), which converts the AC of the city power 200 into DC and outputs it to the battery module 10 to charge the battery module 10, improve the power conversion efficiency, and reduce power loss.

[0044] In some other embodiments, the voltage conversion unit 201 is a bidirectional inverter circuit, which converts the DC power of the battery module 10 into AC power and outputs it to the AC power 200 , and converts the AC power of the AC power 200 into DC power and outputs it to the battery module 10 .

[0045] In some specific embodiments, the voltage conversion unit 201 is composed of a switch. Figure 3 In the example, the voltage conversion unit 201 includes four MOS transistors, namely the first MOS transistor Q1, the second MOS transistor Q2, the third MOS transistor Q3 and the fourth MOS transistor Q4. The first MOS transistor Q1 and the second MOS transistor Q2 form a first bridge arm 2011, and the connection point between the first MOS transistor Q1 and the second MOS transistor Q2 is the midpoint of the first bridge arm 2011. The third MOS transistor Q3 and the fourth MOS transistor Q4 form a second bridge arm 2012, and the connection point between the third MOS transistor Q3 and the fourth MOS transistor Q4 is the midpoint of the second bridge arm 2012. Then, the first circuit is electrically connected to the midpoint of the first bridge arm 2011, and the second circuit is electrically connected to the midpoint of the second bridge arm 2012.

[0046] The gate of each MOS tube is controlled by a control signal, which is sent by the BMS. The BMS controls the conduction and cutoff of each MOS tube through the control signal to achieve voltage conversion.

[0047] The current on the first circuit or the second circuit is an alternating current, and a current sampling circuit is generally required to sample the alternating current for algorithm control and power calculation, etc. The current sampling circuit includes a current sensor 202 and a processing circuit 203. The current sensor 202 is arranged on the first circuit to sample the current flowing through the first circuit, and the sampled current is converted into a sampling voltage, which is then transmitted to the processing circuit 203 for reception and processing. In other implementations, the current sensor 202 is arranged on the second circuit to collect the current flowing through the second circuit.

[0048] In some solutions of the related art, current sampling is implemented by using an isolation operational amplifier or a current transformer. Figure 1 As shown, the scheme of the isolation operational amplifier is to sample the current on the first line or the second line, the reference ground of the sampling point is different from the reference ground of the processing circuit 203, and the potential of the reference ground GND_A of the sampling point is much higher than the potential of the reference ground GND_B of the processing circuit 203. That is, the voltage at the sampling point is much higher than the voltage of the reference ground of the processing circuit 203, so that the processing circuit 203 cannot directly receive the voltage at the sampling point. Therefore, it is necessary to set an isolation chip between the sampling point and the processing circuit 203, and use the isolation chip for isolation and conversion. The isolation chip converts the voltage at the sampling point into a voltage for processing and calculation by the processing circuit 203. However, the conversion of the isolation chip will bring errors, reduce the current sampling accuracy, and the circuit is complicated.

[0049] In other solutions of the related art, a current transformer is arranged on the first line or the second line, and the electromagnetic induction principle is used to convert the large current on the primary side into a small current on the secondary side to sample the current on the first line or the second line. Since the current transformer has the isolation characteristic, the problem that the processing circuit 203 and the sampling point are not grounded is solved. However, the current transformer is composed of a magnetic core and a coil, which takes up a lot of space and has a high circuit cost.

[0050] Based on the above reasons, the embodiment of the present application provides a current sampling circuit, which improves sampling accuracy, has a simple circuit structure and low cost.

[0051] like Figure 4 As shown, Figure 4 2 is a schematic diagram of a current sampling circuit provided in an embodiment of the present application, the current sampling circuit includes a current sensor 202, an operational amplifier, a micro control unit 204 and a power supply circuit 205. The first circuit is electrically connected to a first reference point VREF, and the voltage of the first reference point VREF is defined as a first reference voltage Vref1.

[0052] A current sensor is provided on the first circuit, and the current sensor is used to sample the current flowing through the first circuit and convert the sampled current into a sampled voltage. The sampled voltage is a voltage relative to the first reference voltage Vref1. It is understandable that in other embodiments, the current sensor is provided on the second circuit.

[0053] In some embodiments, the current sensor is a first current sensor 2021, and the operational amplifier is a first operational amplifier op1. Figure 4 As shown, one end of the first current sensor 2021 is electrically connected to the voltage conversion unit 201 and the inverting input end of the first operational amplifier op1, and the other end of the first current sensor 2021 is electrically connected to the first reference point VREF.

[0054] An inductance is provided on the first line, and the inductance is electrically connected between the voltage conversion unit 201 and the mains 200, and is connected in series with the current sensor 202. The inductance is used to filter the current and boost the voltage output from the mains 200 to the battery module 10, thereby achieving power factor correction and improving the power factor.

[0055] A second capacitor C is also provided between the first circuit and the second circuit, one end of the second capacitor C is electrically connected to the first circuit and the first reference point VREF, and the other end of the second capacitor C is electrically connected to the second circuit. The second capacitor C is used to smooth the voltage of the mains 200 and reduce noise and interference on the first circuit or the second circuit.

[0056] Figure 4In the figure, one end of the first current sensor 2021 is connected to the midpoint of the first bridge arm 2011 through the inductance as an example.

[0057] The power circuit 205 is electrically connected to the battery module 10 and the micro control unit 204, respectively. The power circuit 205 performs voltage reduction processing on the first DC voltage output by the battery module 10 to generate a power supply voltage VDD for the micro control unit 204. In addition, the power circuit 205 is electrically connected to the first reference point VREF and the first reference ground, and the ground pin of the micro control unit 204 is electrically connected to the first reference ground GND1. That is, the power circuit 205 generates the power supply voltage VDD and the first reference voltage Vref1, and the power circuit 205 and the reference ground of the control unit are both the first reference ground GND1.

[0058] The voltage of the first reference ground GND1 is defined as the second reference voltage Vref2, and the relationship among the first reference voltage Vref1, the second reference voltage Vref2 and the power supply voltage VDD is: Vref2<Vref1<VDD. The first reference voltage Vref1 is less than the power supply voltage VDD of the micro control unit 204, and the sampling voltage is a voltage with a smaller voltage difference relative to the first reference voltage Vref1. The voltage of the first reference ground GND1 of the micro control unit 204 is the second reference voltage Vref2, and the voltage difference of the sampling voltage relative to the second reference voltage Vref2 is also smaller. Therefore, the operational amplifier directly receives the sampling voltage, and the micro control unit 204 directly receives and processes the sampling voltage. There is no need for isolation conversion between the micro control unit 204 and the current sensor, thereby improving the sampling accuracy.

[0059] In the embodiment of the present application, the positive input terminal of the first operational amplifier op1 is electrically connected to the first reference point VREF, the reverse input terminal of the first operational amplifier op1 is directly electrically connected to the first line, and the output terminal of the first operational amplifier op1 is electrically connected to the micro control unit 204. The reverse input terminal of the first operational amplifier op1 is connected to the sampling voltage, and the sampling voltage is differentially calculated with the voltage Vref1 of the first reference point VREF to obtain a differential amplified signal, and the differential amplified signal is transmitted to the micro control unit 204.

[0060] The micro control unit 204 receives and processes the differential amplified signal, and determines the magnitude of the current flowing through the first circuit according to the differential amplified signal.

[0061] In some embodiments, the micro control unit 204 is a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), a single-chip microcomputer, an ARM (Acorn RISC Machine) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or a combination of these components.

[0062] In some embodiments, the difference between the first reference voltage Vref1 and the second reference voltage Vref2 is less than or equal to a preset threshold. The power supply circuit 205 generates the first reference voltage Vref1 as a reference voltage. As some examples of the present application, the reference voltage is 4.1V, 2.5V, 1.65V, and the supply voltage VDD of the micro control unit 204 is 3.3V or 5V, and the difference between the two is 0.8V, 1.65V, 0.9V, 2.5V, 3.35V. In some embodiments, the preset threshold is set to approximately 3.35V.

[0063] By limiting the difference between the first reference voltage Vref1 and the second reference voltage Vref2, it is ensured that the sampling voltage is a smaller voltage relative to the microprocessing unit, thereby ensuring that the microprocessing unit directly receives and processes the sampling voltage without isolation conversion, thereby improving the sampling accuracy, and the circuit structure is simple, reducing isolation devices, which is more conducive to the circuit layout and wiring of the printed circuit board.

[0064] In the embodiment of the present application, the first current sensor 2021 samples the current flowing through the first line, and converts the sampled current into a sampled voltage, which is a voltage relative to the first reference voltage Vref1, and the sampled voltage is loaded on the reverse input terminal of the first operational amplifier op1, and the first operational amplifier op1 differentially amplifies the sampled voltage and the first reference voltage Vref1 to obtain a differential amplified signal. At the same time, in the embodiment of the present application, the current collected by the first current sensor 2021 is closer to the real current.

[0065] In some embodiments, Figure 5 As shown, in the embodiment of the present application, one end of the first current sensor 2021 is electrically connected to the voltage conversion unit 201 and the first reference point VREF, and the other end of the first current sensor 2021 is electrically connected to the inverting input end of the first operational amplifier op1. The figure takes the example that one end of the first current sensor 2021 is connected to the midpoint of the first bridge arm 2011 through the inductance Inductance.

[0066] In an embodiment of the present application, the first current sensor 2021 samples the current flowing through the first circuit and converts the sampled current into a sampling voltage, which is a voltage relative to the first reference voltage Vref1, and the sampling voltage is loaded on the reverse input terminal of the first operational amplifier op1, and the first operational amplifier op1 differentially amplifies the sampling voltage and the first reference voltage Vref1 to obtain a differential amplification signal.

[0067] In the embodiment of the present application, the first current sensor 2021 is arranged after the second capacitor C to sample the current flowing through the first circuit, so as to remove noise and interference on the first circuit and improve the sampling accuracy. Moreover, since the collected current is smoother, it is more accurate when used for power calculation.

[0068] In some embodiments, the current sensor is two second current sensors 2022, and the operational amplifier is two second operational amplifiers op2. Figure 6 As shown, one end of a second current sensor 2022 is electrically connected to the voltage conversion unit 201 and the inverting input end of a second operational amplifier op2, the other end of a second current sensor 2022 is electrically connected to the first reference point VREF, one end of another second current sensor 2022 is electrically connected to the first reference point VREF, and the other end of another second current sensor 2022 is electrically connected to the inverting input end of another second operational amplifier op2.

[0069] The two second current sensors 2022 sample the current flowing through the first circuit to obtain two sampled voltages, both of which are voltages relative to the first reference voltage Vref1. One sampled voltage is loaded on the reverse input terminal of an operational amplifier, and the operational amplifier performs differential amplification on the sampled voltage and the first reference voltage Vref1 to obtain a differential amplified signal. The other sampled voltage is loaded on the reverse input terminal of another operational amplifier, and the operational amplifier performs differential amplification on the sampled voltage and the first reference voltage Vref1 to obtain another differential amplified signal. The micro control unit 204 receives the two differential amplified signals, and processes and analyzes the two differential amplified signals to obtain the magnitude of the current flowing through the first circuit.

[0070] In the embodiment of the present application, two second current sensors are used to respectively collect the current flowing through the first line. The current collected by the second current sensor close to the voltage conversion unit is closer to the real current and is used for current collection, while the current collected by the second current sensor close to the AC power is smoother and more accurate when used for power calculation.

[0071] In the above embodiment, the current sensor 202 is a sampling resistor, which is not limited here.

[0072] In some embodiments, Figure 7 As shown, the power supply circuit 205 includes a flyback power supply unit 2051 and a linear regulator 2052 electrically connected to the flyback power supply unit 2051. The flyback power supply unit 2051 is electrically connected to the battery module 10, the input end of the linear regulator 2052 is electrically connected to the output end of the flyback power supply unit 2051, the ground end of the linear regulator 2052 is electrically connected to the first reference ground GND1, and the output end of the linear regulator 2052 is electrically connected to the power pin of the micro control unit 204.

[0073] The flyback power supply unit 2051 converts the first DC voltage output by the battery module 10 into an AC voltage by controlling the on and off time of the switch device, and then rectifies and filters the AC voltage to finally output a second DC voltage. The second DC voltage will fluctuate, so a linear regulator 2052 is used to stabilize the second DC voltage and output a stable power supply voltage VDD to ensure the reliable operation of the micro control unit 204.

[0074] In some embodiments, Figure 8 As shown, the power supply circuit 205 further includes a reference voltage generating unit 2053, the reference voltage generating unit 2053 is electrically connected to the output end of the linear regulator 2052, and the output end of the reference voltage generating unit 2053 is electrically connected to the first reference point VREF.

[0075] The reference voltage generating unit 2053 converts the supply voltage VDD into a stable and accurate reference voltage, namely, the first reference voltage Vref1 .

[0076] As some examples of the present application, the first reference voltage Vref1 is half of the power supply voltage VDD. For example, if the power supply voltage is 5V, the first reference voltage Vref1 is 2.5V. For another example, if the power supply voltage is 3.3V, the first reference voltage Vref1 is 1.65V.

[0077] In some embodiments, Fig. 9 As shown, the flyback power supply unit 2051 includes a transformer T1, a switch unit 20511, a drive unit 20512 and a filter unit 20513. The transformer T1 includes a primary winding and a secondary winding coupled to each other. The transformer T1 converts the voltage at its input end by coupling the primary winding and the secondary winding.

[0078] The switch unit 20511 is electrically connected between the battery module 10 and the second reference ground GND2, the output end of the driving unit 20512 is electrically connected to the control end of the switch unit 20511, the ground end of the switch unit 20511 and the ground end of the driving unit 20512 are both electrically connected to the second reference ground GND2, the filter unit 20513 is electrically connected between the output end of the secondary winding and the input end of the linear regulator 2052, and the ground end of the secondary winding and the ground end of the filter unit 20513 are both electrically connected to the first reference ground GND1.

[0079] The driving unit 20512 controls the on and off of the switch unit 20511, so that the primary winding and the secondary winding are coupled to convert the first DC voltage output by the battery module 10 into a coupling voltage. The filtering unit 20513 rectifies and filters the coupling voltage and outputs a second DC voltage.

[0080] Specifically, when the switch unit 20511 is in the on state, the battery module 10, the primary winding and the switch unit 20511 form a primary closed loop, and the primary winding stores energy. When the switch unit 20511 is in the off state, the primary closed loop is disconnected, and the energy of the primary winding is coupled to the secondary winding. The voltage obtained after coupling is rectified and filtered by the filter unit 20513, and a second DC voltage is output.

[0081] The output voltage of the battery module 10 is a first DC voltage, and the coupled voltage is an AC voltage, which is rectified and filtered by the filter unit 20513 to obtain a second DC voltage. The second DC voltage is loaded on the input end of the linear regulator 2052, and the linear regulator 2052 stabilizes the second DC voltage to obtain a supply voltage VDD.

[0082] In some embodiments, please refer to Fig. 9 The flyback power supply unit 2051 also includes an input filter unit 20514 and an absorption unit 20515. The input filter unit 20514 is connected between the battery module 10 and the absorption unit 20515, and the absorption unit 20515 is connected in parallel to the primary side winding.

[0083] The input filter unit 20514 filters the first DC voltage of the battery module 10 , and the filtered first DC voltage is converted into a coupling voltage through coupling between the primary winding and the secondary winding.

[0084] The absorption unit 20515 clamps the switch voltage of the switch unit 20511 in response to the switch unit 20511 being turned off. Specifically, when the switch unit 20511 is in the off state, the energy accumulated in the parasitic inductance of the flyback power supply unit 2051 is charged through the parasitic capacitor in the switch unit 20511, and the switch voltage of the switch unit 20511 rises. When the switch voltage rises to a certain value, the absorption unit 20515 clamps the switch voltage of the switch unit 20511 to suppress the switch voltage. The absorption unit 20515 has many forms, for example, the absorption unit 20515 is a circuit composed of a capacitor and a resistor, or the absorption unit 20515 is a circuit composed of a resistor, a capacitor and a diode, etc.

[0085] In some embodiments, please refer to Fig. 9 The flyback power supply unit 2051 also includes a feedback unit 20516, which is connected between the feedback end of the driving unit 20512 and the battery module 10, and the feedback unit 20516 feeds back the output voltage of the transformer auxiliary winding to the driving unit 20512.

[0086] The output voltage of the transformer auxiliary winding is fed back to the feedback end of the driving unit 20512. The driving unit 20512 controls the duty cycle of its driving signal according to the feedback voltage to control the energy transmitted from the primary winding to the secondary winding, thereby controlling the magnitude of the output second DC voltage.

[0087] like Fig.10 As shown, Fig.10 It is a circuit structure diagram of a power supply circuit provided in an embodiment of the present application. The reference voltage generating unit 2053 includes a first resistor R27, a reference voltage chip U5 and a first capacitor C22. One end of the first resistor R27 is electrically connected to the output end of the linear regulator 2052, and the other end of the first resistor R27 is electrically connected to the cathode of the reference voltage chip U5, the reference end of the reference voltage chip U5, the first reference point VREF and one end of the first capacitor C22 respectively. The anode of the reference voltage chip U5 is electrically connected to the other end of the first capacitor C22 and the first reference ground GND1 respectively.

[0088] The switch unit 20511 includes a MOS tube Q5, and the driving unit 20512 includes a PWM controller U1 and peripheral devices of the PWM controller U1, such as resistors R4, R6, capacitors C6, C8 and C9, etc. The filter unit 20513 includes a diode D1, capacitors C1, C5 and resistor R3.

[0089] The gate of the MOS tube Q5 is connected to the output pin of the PWM controller U1, the source of the MOS tube Q5 is connected to the second reference ground GND2 via a resistor, and the drain of the MOS tube Q5 is connected to the same-name end of the primary winding.

[0090] The opposite-name end of the one-side winding is electrically connected to the battery module 10, the same-name end of the secondary winding is connected to the anode of the diode D1, and the cathode of the diode D1 is connected to the input end of the linear regulator 2052. The capacitor C1, the capacitor C5 and the resistor R3 are respectively connected in parallel between the cathode of the diode D1 and the opposite-name end of the secondary winding, and the opposite-name end of the secondary winding is also electrically connected to the first reference ground GND1.

[0091] The absorption unit 20515 includes a capacitor C4, a resistor R2, and a diode D2. One end of the capacitor C4 is electrically connected to one end of the resistor R2 and the opposite end of the primary winding, the other end of the capacitor C4 is electrically connected to the other end of the resistor R2 and the cathode of the diode D2, and the anode of the diode D2 is electrically connected to the same end of the primary winding.

[0092] The feedback unit 20516 includes a resistor R1, a resistor R5, and a resistor R7. One end of the resistor R1 is electrically connected to the opposite end of the primary winding, the other end of the resistor R1 is electrically connected to one end of the resistor R5 and the power supply end of the PWM controller U1, the other end of the resistor R5 is electrically connected to one end of the resistor R7 and the feedback end of the PWM controller U1, and the other end of the resistor R7 is electrically connected to the second reference ground GND2.

[0093] In the embodiment of the present application, the linear regulator U2 is a low dropout linear regulator LDO, and the reference voltage chip U5 is TL431.

[0094] The first DC voltage output by the battery module 10 supplies power to the power supply terminal of the PWM controller U1 through the resistor R1, so that the PWM controller U1 starts to work. After the output voltage of the transformer auxiliary winding is divided by the resistors R5 and R7, a feedback voltage is generated at the feedback terminal of the PWM controller U1, and the PWM controller U1 outputs a driving signal according to the feedback voltage.

[0095] The PWM controller U1 outputs a driving signal through its output terminal. The driving signal controls the on and off of the MOS tube Q5. By controlling the duty cycle of the driving signal, the on time and off time of the MOS tube Q5 are controlled.

[0096] When the MOS tube Q5 is turned on, the battery module 10, the primary winding and the MOS tube Q5 form a primary closed loop, and the primary winding stores energy. When the MOS tube Q5 is turned off, the electric energy stored on the primary side is coupled with the secondary winding to output a coupled voltage.

[0097] The diode D1 rectifies the coupling voltage, and the capacitors C1, C5 and the resistor R3 filter the rectified coupling voltage to obtain a second DC voltage, which is transmitted to the input end of the linear regulator U2, and the linear regulator U2 stabilizes the second DC voltage to obtain the power supply voltage VDD. The reference voltage chip U5 then generates a first reference voltage Vref1 based on the power supply voltage VDD.

[0098] In an embodiment of the present application, the power supply circuit 205 generates a supply voltage VDD for the micro control unit 204 and a voltage Vref1 of the first reference point VREF, and the micro control unit 204 and part of the circuits in the power supply circuit 205 share a common ground, and the ground pin of the micro control unit 204 and the filter unit 20513, the linear regulator 2052 and the reference voltage generating unit 2053 in the power supply circuit 205 are all electrically connected to the first reference ground GND1.

[0099] To summarize, the second reference voltage Vref2 of the microcontroller unit is less than the first reference voltage Vref1 on the first circuit, and both are less than the power supply voltage VDD of the microcontroller unit, so that the microcontroller unit directly samples the current on the first circuit without setting an isolation circuit between the first circuit and the operational amplifier, thereby reducing current conversion, improving sampling accuracy, and simplifying the circuit structure, thereby reducing circuit cost.

[0100] The above descriptions are merely embodiments of the present application and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

[0101] The above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them. Under the idea of ​​the present application, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order. It should be understood by ordinary technicians in this field that they can still modify the technical solutions recorded in the above embodiments, or replace some of the technical features by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A current sampling circuit, characterized in that: include: A voltage conversion unit is configured such that one side of the voltage conversion unit is electrically connected to the battery module, and the other side of the voltage conversion unit is electrically connected to the mains; a first circuit and a second circuit electrically connected to the voltage conversion unit, the first circuit and the second circuit being configured to be electrically connected to the mains, a current sensor being arranged on the first circuit, the first circuit being electrically connected to a first reference point, and a voltage at the first reference point being defined as a first reference voltage Vref1; An operational amplifier and a micro control unit, wherein the positive input terminal of the operational amplifier is electrically connected to the first reference point, the negative input terminal of the operational amplifier is electrically connected to the first circuit, and the output terminal of the operational amplifier is electrically connected to the micro control unit; a power supply circuit electrically connected to the micro control unit, configured to be electrically connected to the battery module and to generate a power supply voltage VDD for powering the micro control unit, the power supply circuit being electrically connected to the first reference point and a first reference ground, a ground pin of the micro control unit being electrically connected to the first reference ground, and a voltage of the first reference ground being defined as a second reference voltage Vref2; Among them, Vref2<Vref1<VDD.

2. The current sampling circuit according to claim 1, characterized in that: The difference between the first reference voltage Vref1 and the second reference voltage Vref2 is less than or equal to a preset threshold.

3. The current sampling circuit according to claim 1 or 2, characterized in that: The current sensor is a first current sensor, and the operational amplifier is a first operational amplifier; One end of the first current sensor is electrically connected to the voltage conversion unit and the inverting input end of the first operational amplifier, and the other end of the first current sensor is electrically connected to the first reference point; or, One end of the first current sensor is electrically connected to the voltage conversion unit and the first reference point, and the other end of the first current sensor is electrically connected to the inverting input end of the first operational amplifier.

4. The current sampling circuit according to claim 1 or 2, characterized in that: The current sensor is two second current sensors, and the operational amplifier is two second operational amplifiers; One end of one of the second current sensors is electrically connected to the voltage conversion unit and an inverting input end of the first operational amplifier, and the other end of one of the second current sensors is electrically connected to the first reference point; One end of another second current sensor is electrically connected to the first reference point, and the other end of another second current sensor is electrically connected to the inverting input end of another first operational amplifier.

5. The current sampling circuit according to any one of claims 1 to 4, characterized in that: The power supply circuit comprises: a flyback power supply unit and a linear regulator electrically connected to the flyback power supply unit; The flyback power supply unit is configured to be electrically connected to the battery module, the input end of the linear regulator is electrically connected to the output end of the flyback power supply unit, the ground end of the linear regulator is electrically connected to the first reference ground, and the output end of the linear regulator is electrically connected to the power pin of the micro control unit.

6. The current sampling circuit according to claim 5, characterized in that: The power supply circuit includes a reference voltage generating unit electrically connected to the output terminal of the linear regulator; The reference voltage generating unit comprises: a first resistor, a reference voltage chip and a first capacitor; One end of the first resistor is electrically connected to the output end of the linear regulator, the other end of the first resistor is electrically connected to the cathode of the reference voltage chip, the reference end of the reference voltage chip, the first reference point and one end of the first capacitor, and the anode of the reference voltage chip is electrically connected to the other end of the first capacitor and the first reference ground.

7. The current sampling circuit according to claim 5 or 6, characterized in that: The flyback power supply unit includes a transformer, a switch unit, a drive unit and a filter unit; The transformer comprises a primary winding and a secondary winding which are coupled to each other; The switch unit is configured to be electrically connected between the battery module and a second reference ground, the output end of the drive unit is electrically connected to the control end of the switch unit, the ground end of the switch unit and the ground end of the drive unit are both electrically connected to the second reference ground, the filter unit is electrically connected between the output end of the secondary winding and the input end of the linear regulator, and the ground end of the secondary winding and the ground end of the filter unit are both electrically connected to the first reference ground.

8. The sampling circuit according to any one of claims 1 to 7, characterized in that: include: an inductor and a second capacitor; The inductor is arranged on the first circuit and is connected in series with the current sensor; One end of the second capacitor is electrically connected to the first circuit and the first reference point, and the other end of the second capacitor is electrically connected to the second circuit.

9. A battery management system, comprising the current sampling circuit according to any one of claims 1 to 8.

10. A battery device, comprising a battery module and the battery management system according to claim 9, wherein the battery module is electrically connected to the battery management system.

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