Current sampling circuit used in bidirectional converter, bidirectional converter

Abstract

The present invention provides a current sampling circuit and a bidirectional converter for use in a bidirectional converter, wherein the sampling circuit includes a positive half-wave rectifier circuit, a negative half-wave rectifier circuit, and a sampling channel switching control circuit; the input end of the positive half-wave rectifier circuit, the input end of the negative half-wave rectifier circuit, and the first input end of the sampling channel switching control circuit are respectively connected to the differential voltage output end; the positive channel output end of the positive half-wave rectifier circuit and the negative channel output end of the negative half-wave rectifier circuit are respectively connected to the second input end of the sampling channel switching control circuit; when the input current is positive, the positive channel output end of the positive half-wave rectifier circuit is selected as the output; when the input current is negative, the negative channel output end of the negative half-wave rectifier circuit is selected as the output. Thus, accurate sampling of the full load section can be reliably achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronic equipment, and in particular to a current sampling circuit and a bidirectional converter used in a bidirectional converter. Background Art

[0002] The working principle of the bidirectional converter is to realize the bidirectional conversion of energy between two directions by controlling the on and off of the switching device. It has a wide range of application scenarios in the field of energy conversion and control, especially electric vehicles, solar power generation systems, energy storage systems, etc. In these applications, the bidirectional converter can realize efficient conversion and flexible switching of electric energy, improve energy utilization and system stability.

[0003] Bidirectional converters have two working modes: positive and negative, and their working currents are also positive and negative. Figure 1 The figure shows the classic BUCK / BOOST circuit. Although its current inductance belongs to the DC current category, it also has positive and negative currents due to its bidirectional working mode. Figure 1 In the BUCK / BOOST circuit, the inductor current is positive to the right and negative to the left; its inductor current peak is 100A, the positive direction is 0A ~ 100A, and the negative direction is -100A ~ 0A, so its inductor current range is -100A ~ +100A, which requires twice the current range of unidirectional operation, reaching 200A. Figure 2 It is a conventional bidirectional current sampling circuit in the prior art. Figure 2 V_IDC+ and V_IDC- in are from Figure 1 The current sensor corresponds to the differential voltage of the current. This voltage is biased by 3.3V / 2 after the differential proportional circuit and sent to the AD sampling port of the DSP / MCU. Among them, the current of -100A ~ 0A corresponds to the AD port voltage of 0 ~ 1.65V; the current of 0A ~ 100A corresponds to the AD port voltage of 1.65V ~ 3.3V. In other words, the voltage of 0~3.3V at the AD port corresponds to the range of 200A. Due to the existence of positive and negative current sampling, a bias voltage of 3.3V / 2 is required, which leads to an increase in the range; the increase in the range will directly affect the sampling accuracy.

[0004] To solve Figure 2 The sampling accuracy of the bidirectional current sampling circuit is poor. The prior art proposes Figure 3The improved bidirectional current sampling circuit uses two independent sampling circuits of large and small ranges. When the current is greater than a certain threshold, the large-range current sampling circuit channel V_IDC_AD1 is used, and when the current is less than a certain threshold, the small-range current sampling circuit channel V_IDC_AD2 is used (for example: -50A~50A current uses a small-range sampling circuit, while -100A~-50A and 50A~100A use a large-range sampling circuit); then the sampling channel V_IDC_AD1 or V_IDC_AD2 is selected through software.

[0005] Above Figure 3 The improved bidirectional current sampling circuit has a 100A range corresponding to 0~3.3V for each AD port. Figure 2 The conventional solution does improve the sampling accuracy, but it has a fatal disadvantage: when working for a long time under the condition of frequent fluctuations in a large range of loads, the two current sampling channels of large and small ranges need to be switched frequently, which not only fails to improve the current sampling accuracy, but also fails to achieve accurate current sampling. Figure 3 The bidirectional current sampling circuit is not suitable for applications where the load fluctuates frequently and over a large range. Summary of the invention

[0006] The present invention aims to solve at least one of the technical problems in the above-mentioned technology to a certain extent. To this end, the first object of the present invention is to provide a current sampling circuit for a bidirectional converter, which can not only reliably implement full load segment sampling, but also effectively improve the accuracy of full load segment sampling.

[0007] The second object of the present invention is to provide a bidirectional converter that can significantly improve the sampling accuracy of the full load section and be better applied to scenarios where the load fluctuates frequently and over a large range.

[0008] To achieve the above-mentioned purpose, the first embodiment of the present invention proposes a current sampling circuit for a bidirectional converter, comprising: a positive half-wave rectifier circuit, a negative half-wave rectifier circuit and a sampling channel switching control circuit; the input end of the positive half-wave rectifier circuit, the input end of the negative half-wave rectifier circuit and the first input end of the sampling channel switching control circuit are respectively connected to the differential voltage output end; the positive channel output end of the positive half-wave rectifier circuit and the negative channel output end of the negative half-wave rectifier circuit are respectively connected to the second input end of the sampling channel switching control circuit;

[0009] The sampling channel switching control circuit is configured to select the positive channel output end of the positive half-wave rectifier circuit as the output when the output current of the differential voltage output end is positive; and to select the negative channel output end of the negative half-wave rectifier circuit as the output when the output current of the differential voltage output end is negative.

[0010] According to an embodiment of the present invention, a current sampling circuit used in a bidirectional converter performs independent sampling on positive and negative currents respectively, which not only reduces the range of the sampling circuit by half, but also effectively improves the current sampling accuracy within the full load range without sacrificing the load range. At the same time, a sampling channel switching control circuit using pure analog control is used to automatically switch the sampling channel for output according to the positive and negative currents, which can reliably realize full load segment sampling, and the structure is simple and practical.

[0011] In addition, the current sampling circuit for a bidirectional converter according to the above embodiment of the present invention may also have the following additional technical features:

[0012] Optionally, the sampling channel switching control circuit includes a comparator U5, a gating chip U6, a gating chip U7, an electrical interlocking circuit and a sampling output terminal; the positive input terminal of the comparator U5 is connected to the differential voltage output terminal, the negative input terminal is grounded, and the output terminal is connected to the electrical interlocking circuit; the first input terminal of the gating chip U6 is connected to the positive channel output terminal, the second input terminal is connected to the electrical interlocking circuit, and the output terminal is connected to the sampling output terminal; the first input terminal of the gating chip U7 is connected to the negative channel output terminal, the second input terminal is connected to the electrical interlocking circuit, and the output terminal is connected to the sampling output terminal; the first input terminal of the sampling channel switching control circuit is the positive input terminal of the comparator U5; the second input terminal of the sampling channel switching control circuit includes the first input terminal of the gating chip U6 and the first input terminal of the gating chip U7;

[0013] The comparator U5 is configured to determine whether the output current of the differential voltage output terminal is a positive current or a negative current;

[0014] The electrical interlock circuit is configured to control the enable chip U6 to be turned on and lock the enable chip U7 in the off state when the judgment result of the comparator U5 is a positive current; when the judgment result of the comparator U5 is a negative current, control the enable chip U7 to be turned on and lock the enable chip U6 in the off state.

[0015] Optionally, the electrical interlocking circuit includes a transistor Q1 and a transistor Q2; the base of the transistor Q1 is respectively connected to the output terminal and the ground terminal of the comparator U5, the emitter is connected to the ground terminal, and the collector is respectively connected to the second input terminal of the gating chip U7, the power supply VCC and the base of the transistor Q2; the base of the transistor Q2 is connected to the collector of the transistor Q1, the emitter is connected to the power supply VCC, and the collector is respectively connected to the second input terminal and the ground terminal of the gating chip U6.

[0016] Optionally, the sampling channel switching control circuit further includes a resistor R1; the resistor R1 is connected in parallel between the positive input terminal and the output terminal of the comparator U5.

[0017] Optionally, the sampling channel switching control circuit further includes a diode D5 and a voltage regulator ZD1; the cathode of the diode D5 is connected to the output end of the comparator U5, and the anode is connected to the ground end; the output end of the comparator U5 is further connected to the electrical interlocking circuit via the voltage regulator ZD1.

[0018] Optionally, the forward half-wave rectifier circuit includes an operational amplifier U2, an operational amplifier U3, a diode D1 and a diode D2; the negative input terminal of the operational amplifier U2 is connected to the differential voltage output terminal, the positive input terminal is connected to the ground terminal, and the output terminal is connected to the cathode of the diode D2; the anode of the diode D2 is connected to the ground terminal through a first resistor, and is connected to the negative input terminal of the operational amplifier U3 through a second resistor; the positive input terminal of the operational amplifier U3 is connected to the ground terminal through a third resistor, and its negative input terminal is connected to its output terminal through a fourth resistor; the output terminal of the operational amplifier U3 serves as the forward channel output terminal; the anode of the diode D1 is connected to the output terminal of the operational amplifier U2, and the cathode is connected to the negative input terminal of the operational amplifier U2.

[0019] Optionally, the negative half-wave rectifier circuit includes an operational amplifier U4, a diode D3 and a diode D4; the negative input terminal of the operational amplifier U4 is connected to the differential voltage output terminal, the positive input terminal is connected to the ground terminal, and the output terminal is connected to the anode of the diode D4; the cathode of the diode D4 is connected to the ground terminal and also serves as the negative channel output terminal; the anode of the diode D3 is connected to the negative input terminal of the operational amplifier U4, and the cathode is connected to the output terminal of the operational amplifier U4.

[0020] Optionally, a differential circuit is further included; the input end of the differential circuit is connected to the output end of the Hall current sensor HCT or the output end of the current transformer CT, and the output end serves as the differential voltage output end.

[0021] Optionally, the differential circuit includes an input terminal V_IDC+, an input terminal V_IDC-, an operational amplifier U1, a capacitor C1, a capacitor C2, a resistor R4, a resistor R2 and a resistor R3; the input terminal V_IDC+ is connected to the positive input terminal of the operational amplifier U1; the input terminal V_IDC- is connected to the negative input terminal of the operational amplifier U1; after the capacitor C1 and the resistor R4 are connected in parallel, one end is grounded, and the other end is connected to the positive input terminal of the operational amplifier U1; after the capacitor C2 and the resistor R2 are connected in parallel, one end is connected to the negative input terminal of the operational amplifier U1, and the other end is connected to the output terminal of the operational amplifier U1; the output terminal of the operational amplifier U1 serves as the differential voltage output terminal.

[0022] To achieve the above object, a second embodiment of the present invention provides a bidirectional converter, including the above-mentioned current sampling circuit used in the bidirectional converter.

[0023] According to a bidirectional converter provided by this embodiment, the current sampling circuit provided by the above embodiment can not only reliably implement full load segment sampling, but also effectively improve the accuracy of full load segment sampling, so as to be better applied to scenarios where the load fluctuates frequently and widely. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the classic BUCK / BOOST circuit structure in the prior art;

[0025] Figure 2 It is a schematic diagram of the structure of a conventional bidirectional current sampling circuit in the prior art;

[0026] Figure 3 It is a structural schematic diagram of an improved bidirectional current sampling circuit in the prior art;

[0027] Figure 4 A schematic diagram of the circuit module composition of a current sampling circuit used in a bidirectional converter provided by an embodiment of the present invention;

[0028] Figure 5 An example diagram of sampling of the voltages at points A, C and D when the current sampling circuit provided in a specific embodiment of the present invention samples the BUCK / BOOST forward inductor current;

[0029] Figure 6 An example diagram of sampling of the voltages at points A, C and D when the current sampling circuit provided in a specific embodiment of the present invention samples the BUCK / BOOST negative inductor current;

[0030] Figure 7 A schematic diagram of the circuit structure of a current sampling circuit used in a bidirectional converter provided in a specific embodiment of the present invention;

[0031] Figure 8 It is a structural schematic diagram of using the Hall (HCT) output as the differential circuit input in a specific implementation manner of the present invention;

[0032] Fig. 9 It is a structural schematic diagram of using the current transformer (CT) output as the differential circuit input in a specific implementation manner of the present invention;

[0033] Fig.10 This is an example diagram of sampling the voltages at points A, C and D when the current sampling circuit provided in an embodiment of the present invention samples alternating AC current.

[0034] Description of Figure Numbers:

[0035] 100. Current sampling circuit;

[0036] 101. Forward half-wave rectifier circuit;

[0037] 102. Negative half-wave rectifier circuit;

[0038] 103. Sampling channel switching control circuit;

[0039] 31. Electrical interlock circuit;

[0040] 104. Differential circuit. DETAILED DESCRIPTION

[0041] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0042] Different from the prior art that determines the use of large / small range sampling circuits for sampling by comparing with a threshold, when working for a long time under a large range of load and frequent fluctuations, not only can the sampling accuracy not be improved, but even accurate current sampling cannot be achieved. The present invention performs independent sampling according to positive and negative currents, and uses an analog control circuit to achieve automatic switching output. It can not only effectively improve the current sampling accuracy within the full load range, but more importantly, it can ensure stable and reliable accurate sampling within the full load range.

[0043] In order to better understand the above technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0044] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0045] Figure 4 A schematic diagram of the circuit module composition of a current sampling circuit for a bidirectional converter provided in an embodiment of the present invention.

[0046] like Figure 4 As shown, an embodiment of the present invention provides a current sampling circuit 100 for a bidirectional converter, comprising: a positive half-wave rectifier circuit 101, a negative half-wave rectifier circuit 102, and a sampling channel switching control circuit 103; the input end of the positive half-wave rectifier circuit 101, the input end of the negative half-wave rectifier circuit 102, and the first input end of the sampling channel switching control circuit 103 are respectively connected to the differential voltage output end; the positive channel output end of the positive half-wave rectifier circuit 101 and the negative channel output end of the negative half-wave rectifier circuit 102 are respectively connected to the second input end of the sampling channel switching control circuit 103;

[0047] The forward half-wave rectifier circuit is configured to filter out the negative half-wave of the input current and output the positive half-wave when the output current of the differential voltage output terminal is positive;

[0048] The negative half-wave rectifier circuit is configured to filter out the positive half-wave of the input current and flip the negative half-wave to the positive half-wave before outputting the current when the output current of the differential voltage output terminal is negative;

[0049] The sampling channel switching control circuit is configured to select the positive channel output end of the positive half-wave rectifier circuit as the output when the output current of the differential voltage output end is positive; and to select the negative channel output end of the negative half-wave rectifier circuit as the output when the output current of the differential voltage output end is negative.

[0050] The current sampling circuit used in the bidirectional converter provided in this embodiment has the following working principle:

[0051] (1) When the output current at the differential voltage output end is positive, the voltage V_A at point A is greater than 0; at this time, the negative half-wave rectifier circuit is cut off and does not work, and the voltage V_D at the negative channel output end point D is 0; the positive half-wave rectifier circuit is turned on, filtering out the negative half-wave of the input current and outputting the positive half-wave, and the voltage V_C at the positive channel output end point C is K×V_A; the sampling channel switching control circuit selects the positive channel output end of the forward half-wave rectifier circuit as the output, that is, V_I_DC_AD=V_C+V_D=K×V_A.

[0052] Taking the BUCK / BOOST forward inductor current, K=1 as an example, point A is the sampling voltage corresponding to the positive inductor current, then the sampling examples of point A voltage, point C voltage and point D voltage are as follows: Figure 5 shown.

[0053] (2) When the output current at the differential voltage output end is negative, the voltage V_A at point A is less than 0; at this time, the positive half-wave rectifier circuit is cut off and does not work, and the voltage V_C at the positive channel output point C is 0; the negative half-wave rectifier circuit is turned on, the input current is filtered out of the positive half-wave and the negative half-wave is flipped to the positive half-wave before output processing, and the voltage V_C at the negative channel output point D is -K×V_A; the sampling channel switching control circuit selects the negative channel output end of the negative half-wave rectifier circuit as the output, that is, V_I_DC_AD=V_C+V_D=-K×V_A.

[0054] Taking the BUCK / BOOST negative inductor current, K=1 as an example, point A is the sampling voltage corresponding to the negative inductor current, then the sampling examples of point A voltage, point C voltage and point D voltage are as follows: Figure 6 shown.

[0055] The current sampling circuit provided in this embodiment is used in a bidirectional converter. It can automatically match the corresponding positive half-wave rectifier circuit / negative half-wave rectifier circuit according to the positive / negative direction of the input current sampling for rectification and output. The voltage of 0~3.3V at the output AD port corresponds to the range of 100A, and the range is reduced to half of the original range. The current sampling accuracy within the full load range is effectively improved without sacrificing the load measurement range. It is further combined with a selection method using pure analog control, thereby not only reliably realizing accurate sampling of the full load segment, but also effectively improving the sampling accuracy of the full load segment, which is simple, reliable and practical.

[0056] Preferably, the forward half-wave rectifier circuit described in this embodiment is a forward precision half-wave rectifier circuit; the negative half-wave rectifier circuit is a negative precision half-wave rectifier circuit, so as to eliminate the influence of the diode voltage drop during the voltage sampling process to the greatest extent, ensure the accuracy of the sampling, and better adapt to the high-precision rectification requirements of voltage sampling.

[0057] In some specific implementations of this embodiment, Figure 7 As shown, the sampling channel switching control circuit 103 includes a comparator U5, a gating chip U6, a gating chip U7, an electrical interlocking circuit 31 and a sampling output terminal V_I_DC_AD; the positive input terminal of the comparator U5 is connected to the differential voltage output terminal, the negative input terminal is grounded, and the output terminal is connected to the electrical interlocking circuit 31; the first input terminal of the gating chip U6 is connected to the positive channel output terminal, the second input terminal is connected to the electrical interlocking circuit 31, and the output terminal is connected to the sampling output terminal; the first input terminal of the gating chip U7 is connected to the negative channel output terminal, the second input terminal is connected to the electrical interlocking circuit 31, and the output terminal is connected to the sampling output terminal V_I_DC_AD;

[0058] The comparator U5 is configured to determine whether the output current of the differential voltage output terminal is a positive current or a negative current;

[0059] The electrical interlock circuit is configured to control the gate chip U6 to be turned on and lock the gate chip U7 in the off state when the judgment result of the comparator U5 is a positive current; when the judgment result of the comparator U5 is a negative current, control the gate chip U7 to be turned on and lock the gate chip U6 in the off state. In other words, under the control of the electrical interlock circuit, only one of the dual-channel multiplexed gate chip U6 and gate chip U7 can be turned on, so only one sampling channel can be output at the same time.

[0060] As a specific example, Figure 7 As shown, the electrical interlocking circuit 31 is mainly composed of a transistor Q1 and a transistor Q2; the base of the transistor Q1 is respectively connected to the output terminal and the ground terminal of the comparator U5, the emitter is connected to the ground terminal, and the collector is respectively connected to the second input terminal of the gating chip U7, the power supply VCC and the base of the transistor Q2; the base of the transistor Q2 is connected to the collector of the transistor Q1, the emitter is connected to the power supply VCC, and the collector is respectively connected to the second input terminal and the ground terminal of the gating chip U6.

[0061] The working principle of the above sampling channel switching control circuit is:

[0062] (1) When the output current of the differential voltage output terminal is a forward current, the corresponding sampling voltage at point A is positive, the output of comparator U5 is set high, transistor Q1 is turned on, the second input terminal CS_EN_2 of the gate chip U7 is set low, and the gate chip U7 is turned off; at the same time, transistor Q2 is turned on, the second input terminal CS_EN_1 of the gate chip U6 is set high, and the gate chip U6 is turned on; at this time, the voltage at point C of the output terminal of the forward half-wave rectifier circuit is the final output voltage, that is, V_IDC_AD=V_C.

[0063] (2) When the output current of the differential voltage output terminal is negative, the corresponding sampling voltage at point A is negative, the output of comparator U5 is set low, transistor Q1 is cut off, the second input terminal CS_EN_2 of the enable chip U7 is set high, and the enable chip U7 is turned on; at the same time, transistor Q2 is cut off, the second input terminal CS_EN_1 of the enable chip U6 is set low, and the enable chip U6 is turned off; at this time, the voltage at point D of the negative half-wave rectifier circuit is the final output voltage, that is, V_IDC_AD=V_D.

[0064] Here, the sampling channel switching control circuit realizes that only one sampling channel is output at the same time through the electrical interlocking circuit composed of transistor Q1 and transistor Q2. In other words, the function of the sampling channel switching control circuit is to control which channel is used as output according to the positive and negative directions of the current.

[0065] In summary, the working principle of the sampling channel switching control circuit can be summarized as follows:

[0066] When the input current sampling is positive, the gating chip U6 is turned on, the gating chip U7 is turned off, and the forward rectifier channel is used as the final output V_IDC_AD=V_C;

[0067] When the input current sampling is negative, the enable chip U6 is turned off, the enable chip U7 is turned on, and the negative rectification channel serves as the final output V_IDC_AD=V_D.

[0068] As another specific example, the sampling channel switching control circuit further includes a resistor R1; the resistor R1 is connected in parallel between the positive input terminal and the output terminal of the comparator U5.

[0069] Here, the resistor R1 as a feedback voltage can add positive feedback in the comparator U5 to generate hysteresis, which can effectively avoid frequent automatic switching of the sampling channel to affect the sampling accuracy and play an anti-interference role.

[0070] Specifically, when the input current sampling of the current sampling circuit is 0, that is, the sampling voltage at point A is 0 or close to 0 in the no-load state, since positive feedback is added to the comparator U5 to generate hysteresis, the positive channel output terminal voltage V_C of the positive half-wave rectifier circuit and the negative channel output terminal voltage V_D of the negative half-wave rectifier circuit are both close to 0. At this time, the final output V_IDC_AD=V_C+V_D=0, and no matter which sampling channel is selected, it will not affect the final sampling value.

[0071] As another specific example, Figure 7As shown, the sampling channel switching control circuit also includes a diode D5 and a voltage regulator ZD1; the cathode of the diode D5 is connected to the output end of the comparator U5, and the anode is connected to the ground end; the output end of the comparator U5 is connected to the electrical interlocking circuit via the voltage regulator ZD1.

[0072] Here, the diode D5 is used for clamping to ensure that the output of the comparator U5 is greater than or equal to the GND level; the voltage regulator ZD1 is used to limit the output voltage for anti-interference processing to avoid mis-conduction of the transistor Q1.

[0073] In some other specific implementations of this embodiment, Figure 7 As shown, the forward half-wave rectifier circuit 101 includes an operational amplifier U2, an operational amplifier U3, a diode D1 and a diode D2; the negative input terminal of the operational amplifier U2 is connected to the differential voltage output terminal, the positive input terminal is connected to the ground terminal, and the output terminal is connected to the cathode of the diode D2; the anode of the diode D2 is connected to the ground terminal through a first resistor, and is connected to the negative input terminal of the operational amplifier U3 through a second resistor; the positive input terminal of the operational amplifier U3 is connected to the ground terminal through a third resistor, and its negative input terminal is connected to its output terminal through a fourth resistor; the output terminal of the operational amplifier U3 serves as the forward channel output terminal; the anode of the diode D1 is connected to the output terminal of the operational amplifier U2, and the cathode is connected to the negative input terminal of the operational amplifier U2.

[0074] Here, the working principle of the forward half-wave rectifier circuit is:

[0075] (1) When the output current of the differential voltage output terminal is positive, the corresponding sampling voltage V_A at point A is greater than 0. At this time, diode D1 is cut off, diode D2 is turned on, and operational amplifier U2 is equivalent to an inverting proportional amplifier circuit. The voltage at point B V_B = -K × V_A; after being processed by the inverting proportional amplifier U3, the voltage at point C at the output terminal V_C = -V_B = K × V_A;

[0076] (2) When the output current of the differential voltage output terminal is negative, the sampling voltage V_A corresponding to point A is less than 0. At this time, diode D1 is turned on, diode D2 is turned off, and the voltage at point B is clamped to 0, that is, V_B=0; after being processed by the inverting proportional amplifier of U3 operational amplifier, the voltage at point C of the output terminal V_C=-V_B=0;

[0077] Therefore, through the processing of the forward half-wave rectifier circuit, the negative half-wave in the input current is removed (the negative half-wave clamped output is 0), and only the positive half-wave is output.

[0078] In some other specific implementations of this embodiment, Figure 7As shown, the negative half-wave rectifier circuit 102 includes an operational amplifier U4, a diode D3 and a diode D4; the negative input terminal of the operational amplifier U4 is connected to the differential voltage output terminal, the positive input terminal is connected to the ground terminal, and the output terminal is connected to the anode of the diode D4; the cathode of the diode D4 is connected to the ground terminal and serves as the negative channel output terminal; the anode of the diode D3 is connected to the negative input terminal of the operational amplifier U4, and the cathode is connected to the output terminal of the operational amplifier U4.

[0079] Here, the working principle of the negative half-wave rectifier circuit is:

[0080] (1) When the output current of the differential voltage output terminal is positive, the sampling voltage V_A corresponding to point A is greater than 0, diode D3 is turned on, diode D4 is turned off, and the voltage at point D is clamped to 0, V_D = 0;

[0081] (2) When the output current at the differential voltage output terminal is negative, the sampling voltage V_A corresponding to point A is less than 0, the diode D3 is cut off, the diode D4 is turned on, and the operational amplifier U4 is equivalent to an inverting proportional amplifier circuit. The voltage at point D V_D = -K × V_A; the negative voltage is flipped to positive.

[0082] Therefore, through the processing of the negative half-wave rectifier circuit, the positive half-wave in the input current is removed (the positive half-wave clamped output is 0), and only the negative half-wave is flipped to positive and then output.

[0083] In some other specific implementations, the current sampling circuit for a bidirectional converter provided in this embodiment is as follows: Figure 7 As shown, it also includes a differential circuit 104; the input end of the differential circuit 104 is connected to the output end of the Hall current sensor HCT or the output end of the current transformer CT, and the output end serves as the differential voltage output end, which is respectively connected to the positive half-wave rectifier circuit 101, the negative half-wave rectifier circuit 102 and the sampling channel switching control circuit 103.

[0084] Here, the input terminals of the differential circuit include V_IDC+ and V_IDC-. The V_IDC+ and V_IDC- can be directly output from the Hall effect (HCT), such as Figure 8 It can also come from the output of a current transformer (CT), such as Fig. 9 As shown. The output of the Hall (HCT) is a voltage signal, and the current transformer CT is also converted into a voltage signal after passing through the sampling resistor. The above voltage signal is the voltage difference between the input terminals V_IDC+ and V_IDC- of the differential circuit.

[0085] The input terminals V_IDC+ and V_IDC- of the differential circuit will first pass through a differential ratio to obtain the voltage at point A. The current has positive and negative directions, and the voltage at point A also has positive and negative directions. When the current is positive, the sampling voltage corresponding to point A is positive; when the current is negative, the sampling voltage corresponding to point A is negative.

[0086] As a specific example, the differential circuit includes an input terminal V_IDC+, an input terminal V_IDC-, an operational amplifier U1, a capacitor C1, a capacitor C2, a resistor R4, a resistor R2 and a resistor R3; the input terminal V_IDC+ is connected to the positive input terminal of the operational amplifier U1; the input terminal V_IDC- is connected to the negative input terminal of the operational amplifier U1; after the capacitor C1 and the resistor R4 are connected in parallel, one end is grounded, and the other end is connected to the positive input terminal of the operational amplifier U1; after the capacitor C2 and the resistor R2 are connected in parallel, one end is connected to the negative input terminal of the operational amplifier U1, and the other end is connected to the output terminal of the operational amplifier U1; the output terminal of the operational amplifier U1 serves as the differential voltage output terminal.

[0087] Furthermore, in this embodiment, preferably, U1 to U5 are dual-power-supply operational amplifiers; U6 and U7 are dual-channel multiplexed selection chips.

[0088] See also Fig.10 , Fig.10 This is an example diagram of sampling the voltages at points A, C and D when the current sampling circuit provided in an embodiment of the present invention samples alternating AC current.

[0089] The present invention is further developed based on the above embodiment and is applied to sampling alternating AC current.

[0090] The following is an explanation using the LLC resonant cavity AC current, a 100kHz alternating sine wave as an example.

[0091] According to the working principle of the current sampling circuit provided in the above embodiment: V_I_DC_AD=V_C+V_D=|-K×V_A|; the 100kHz alternating sine wave passes through two independent precision half-wave rectification sampling circuits to obtain a 200kHz positive half-wave and is sent to the AD port, so that the DSP / MCU can accurately implement sampling. In this embodiment, the sampling examples of the voltage at point A, the voltage at point C, and the voltage at point D are as follows: Fig.10 shown.

[0092] Based on the above embodiment, the present invention also provides a bidirectional converter, which includes the above current sampling circuit for bidirectional converter. The specific structure of the current sampling circuit is not repeated here, please refer to the above embodiment for details.

[0093] In summary, the current sampling circuit and the bidirectional converter provided by the present invention are used in a bidirectional converter, which can automatically match the corresponding positive / negative half-wave rectifier circuits for independent sampling according to the positive / negative phase of the input current. Since two precision half-wave rectifier circuits are innovatively integrated, their respective ranges can be effectively reduced to improve the sampling accuracy. The sampling channel switching control circuit is further combined with the analog control to realize automatic switching of the sampling channel according to the positive and negative currents for output, thereby realizing reliable full-load segment sampling. At the same time, the accuracy of full-load segment sampling is effectively improved.

[0094] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0095] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0096] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0097] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1The steps for the functions specified in one or more boxes.

[0098] It should be noted that in the claims, any reference signs placed between brackets shall not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claim. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention may be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In a unit claim enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third etc. does not indicate any order. These words may be interpreted as names.

[0099] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0100] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

[0101] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0102] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0103] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0104] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms should not be understood as necessarily being directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0105] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A current sampling circuit for a bidirectional converter, characterized in that: include: A positive half-wave rectification circuit, a negative half-wave rectification circuit and a sampling channel switching control circuit; The input end of the positive half-wave rectifier circuit, the input end of the negative half-wave rectifier circuit and the first input end of the sampling channel switching control circuit are respectively connected to the differential voltage output end; the positive channel output end of the positive half-wave rectifier circuit and the negative channel output end of the negative half-wave rectifier circuit are respectively connected to the second input end of the sampling channel switching control circuit; The sampling channel switching control circuit is configured to select the forward channel output terminal of the forward half-wave rectifier circuit as the output when the output current of the differential voltage output terminal is positive; When the output current of the differential voltage output terminal is negative, the negative channel output terminal of the negative half-wave rectifier circuit is selected as the output; The sampling channel switching control circuit comprises a comparator U5, a gating chip U6, a gating chip U7, an electrical interlocking circuit and a sampling output terminal; the positive input terminal of the comparator U5 is connected to the differential voltage output terminal, the negative input terminal is grounded, and the output terminal is connected to the electrical interlocking circuit; the first input terminal of the gating chip U6 is connected to the positive channel output terminal, the second input terminal is connected to the electrical interlocking circuit, and the output terminal is connected to the sampling output terminal; the first input terminal of the gating chip U7 is connected to the negative channel output terminal, the second input terminal is connected to the electrical interlocking circuit, and the output terminal is connected to the sampling output terminal; the first input terminal of the sampling channel switching control circuit is the positive input terminal of the comparator U5; the second input terminal of the sampling channel switching control circuit comprises the first input terminal of the gating chip U6 and the first input terminal of the gating chip U7; The comparator U5 is configured to determine whether the output current of the differential voltage output terminal is a positive current or a negative current; The electrical interlock circuit is configured to control the enable chip U6 to be turned on and lock the enable chip U7 in the off state when the judgment result of the comparator U5 is a positive current; when the judgment result of the comparator U5 is a negative current, control the enable chip U7 to be turned on and lock the enable chip U6 in the off state.

2. A current sampling circuit for a bidirectional converter as claimed in claim 1, characterized in that: The electrical interlocking circuit includes a transistor Q1 and a transistor Q2; the base of the transistor Q1 is respectively connected to the output terminal and the ground terminal of the comparator U5, the emitter is connected to the ground terminal, and the collector is respectively connected to the second input terminal of the gating chip U7, the power supply VCC and the base of the transistor Q2; the base of the transistor Q2 is connected to the collector of the transistor Q1, the emitter is connected to the power supply VCC, and the collector is respectively connected to the second input terminal and the ground terminal of the gating chip U6.

3. A current sampling circuit for a bidirectional converter as claimed in claim 1, characterized in that: The sampling channel switching control circuit further includes a resistor R1; the resistor R1 is connected in parallel between the positive input terminal and the output terminal of the comparator U5.

4. A current sampling circuit for a bidirectional converter as claimed in claim 1, characterized in that: The sampling channel switching control circuit also includes a diode D5 and a voltage regulator ZD1; the cathode of the diode D5 is connected to the output end of the comparator U5, and the anode is connected to the ground end; the output end of the comparator U5 is connected to the electrical interlocking circuit via the voltage regulator ZD1.

5. The current sampling circuit for a bidirectional converter according to claim 1, characterized in that: The forward half-wave rectifier circuit includes an operational amplifier U2, an operational amplifier U3, a diode D1 and a diode D2; the negative input terminal of the operational amplifier U2 is connected to the differential voltage output terminal, the positive input terminal is connected to the ground terminal, and the output terminal is connected to the cathode of the diode D2; the anode of the diode D2 is connected to the ground terminal through a first resistor, and is connected to the negative input terminal of the operational amplifier U3 through a second resistor; the positive input terminal of the operational amplifier U3 is connected to the ground terminal through a third resistor, and its negative input terminal is connected to its output terminal through a fourth resistor; the output terminal of the operational amplifier U3 serves as the forward channel output terminal; the anode of the diode D1 is connected to the output terminal of the operational amplifier U2, and the cathode is connected to the negative input terminal of the operational amplifier U2.

6. A current sampling circuit for a bidirectional converter as claimed in claim 1, characterized in that: The negative half-wave rectifier circuit includes an operational amplifier U4, a diode D3 and a diode D4; the negative input terminal of the operational amplifier U4 is connected to the differential voltage output terminal, the positive input terminal is connected to the ground terminal, and the output terminal is connected to the anode of the diode D4; the cathode of the diode D4 is connected to the ground terminal and also serves as the negative channel output terminal; the anode of the diode D3 is connected to the negative input terminal of the operational amplifier U4, and the cathode is connected to the output terminal of the operational amplifier U4.

7. A current sampling circuit for a bidirectional converter as claimed in claim 1, characterized in that: It also includes a differential circuit; the input end of the differential circuit is connected to the output end of the Hall current sensor HCT or the output end of the current transformer CT, and the output end serves as the differential voltage output end.

8. A current sampling circuit for a bidirectional converter as claimed in claim 7, characterized in that: The differential circuit includes an input terminal V_IDC+, an input terminal V_IDC-, an operational amplifier U1, a capacitor C1, a capacitor C2, a resistor R4, a resistor R2 and a resistor R3; the input terminal V_IDC+ is connected to the positive input terminal of the operational amplifier U1; the input terminal V_IDC- is connected to the negative input terminal of the operational amplifier U1; the capacitor C1 and the resistor R4 are connected in parallel, one end of which is grounded, and the other end is connected to the positive input terminal of the operational amplifier U1; the capacitor C2 and the resistor R2 are connected in parallel, one end of which is connected to the negative input terminal of the operational amplifier U1, and the other end is connected to the output terminal of the operational amplifier U1; the output terminal of the operational amplifier U1 serves as the differential voltage output terminal.

9. A bidirectional converter, characterized in that: A current sampling circuit for a bidirectional converter comprising the current sampling circuit described in any one of claims 1 to 8.

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