Current limiter and power system

Abstract

The present disclosure discloses a current limiter and a power system, relating to the electrical field. The current limiter includes: a sampling circuit, the first end of the sampling circuit is connected to the first end of the current limiter and is configured to sample the voltage and current in the DC line; a switching circuit, the first end of the switching circuit is connected to the second end of the sampling circuit, and the second end of the switching circuit is connected to the second end of the current limiter; and a control circuit, the first end of the control circuit is respectively connected to the first end and the second end of the sampling circuit, and the second end of the control circuit is connected to the control end of the switching circuit and is configured to output a pulse signal to the switching circuit according to the sampling result of the sampling circuit to control the switching speed of the switching circuit. The present disclosure can control the switching speed of the switching circuit when an abnormality occurs in the DC line, so as to reduce the current in the DC line, keep the current in the DC line stable within the normal operating range, and improve the stability of the power system.

Description

Technical Field

[0001] The present disclosure relates to the electrical field, and particularly to a current limiter and a power system. Background Art

[0002] With the development of power systems and modern industries, large power grid interconnection and cross-regional interconnection are underway. Under the trend of DC power, DC applications are more extensive, and the single-unit capacity is increasing continuously, resulting in an increasing short-circuit capacity of the power system.

[0003] In current technical applications, current limiters for alternating current have been widely used, especially in DC lines such as substations, large-load electrical equipment, and precision and high-cost equipment. However, these current limiters are all high-power, mechanical current limiters, which are not suitable for scenarios such as medium and small power, and moreover, AC current limiters cannot be applied to DC systems. Summary of the Invention

[0004] One technical problem to be solved by the present disclosure is to provide a current limiter and a power system that can keep the current in the DC line stable within the normal operating range.

[0005] According to one aspect of the present disclosure, a current limiter is proposed, including: a sampling circuit, the first end of the sampling circuit is connected to the first end of the current limiter and is configured to sample the voltage and current in the DC line; a switching circuit, the first end of the switching circuit is connected to the second end of the sampling circuit, and the second end of the switching circuit is connected to the second end of the current limiter; and a control circuit, the first end of the control circuit is respectively connected to the first end and the second end of the sampling circuit, and the second end of the control circuit is connected to the control end of the switching circuit and is configured to output a pulse signal to the switching circuit according to the sampling result of the sampling circuit to control the switching speed of the switching circuit.

[0006] In some embodiments, the control circuit is further configured to output a pulse signal to the switching circuit to control the switching speed of the switching circuit when receiving any one of a charging instruction and a discharging instruction.

[0007] In some embodiments, if the DC line is abnormal, the greater the current in the DC line, the smaller the duty cycle of the pulse signal.

[0008] In some embodiments, the voltage at the first end of the switching circuit is higher than the voltage at the second end of the switching circuit.

[0009] In some embodiments, the switching circuit includes: an inductor, the first end of the inductor is connected to the first end of the current limiter; and a first switch, the first end of the first switch is connected to the second end of the inductor, the second end of the first switch is connected to the second end of the current limiter, and the control end of the first switch is connected to the second end of the control circuit.

[0010] In some embodiments, the switching circuit further includes: a diode, an anode of the diode is connected to a first end of the first switch, and a cathode of the diode is connected to a second end of the first switch.

[0011] In some embodiments, the switching circuit further includes: a lightning protection tube, a first end of the lightning protection tube is connected to a first end of the first switch, and a second end of the lightning protection tube is connected to a second end of the first switch.

[0012] In some embodiments, the control circuit includes: a current acquisition circuit configured to acquire a current value sampled by the sampling circuit; a voltage acquisition circuit configured to acquire a voltage value sampled by the sampling circuit; a monitoring chip respectively connected to the current acquisition circuit and the voltage acquisition circuit and configured to perform arithmetic processing on the current value and the voltage value; a controller connected to the monitoring chip and configured to determine whether an abnormality occurs in the DC line according to an output result of the monitoring chip, and if an abnormality occurs, output duty cycle information of a pulse signal to a pulse output circuit; and a pulse output circuit connected to the controller and configured to generate a pulse signal with the duty cycle information and send the pulse signal to the switching circuit.

[0013] In some embodiments, the control circuit further includes: a communication circuit connected to the controller, wherein the controller receives any one of a charging instruction and a discharging instruction through the communication circuit.

[0014] According to another aspect of the present disclosure, there is also provided a power system including the above current limiter.

[0015] In the embodiments of the present disclosure, by providing a sampling circuit, a switching circuit and a control circuit, a pulse signal can be output to the switching circuit when an abnormality occurs in the DC line to control the switching speed of the switching circuit, so that the DC line current can be reduced, the DC line current can be stably maintained within the normal operating range, and the stability of the power system is improved.

[0016] Other features and advantages of the present disclosure will become clear from the following detailed description of the exemplary embodiments of the present disclosure with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings forming a part of the specification depict embodiments of the present disclosure and, together with the specification, are used to explain the principles of the present disclosure.

[0018] Referring to the accompanying drawings, the present disclosure can be more clearly understood from the following detailed description, wherein:

[0019] Figure 1 is a schematic structural diagram of some embodiments of the current limiter of the present disclosure.

[0020] Figure 2Schematic diagram of some other embodiments of the current limiter of the present disclosure.

[0021] Figure 3 Schematic diagram of some embodiments of the power system of the present disclosure. Detailed implementation manners

[0022] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that: unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions and values set forth in these embodiments do not limit the scope of the present disclosure.

[0023] Meanwhile, it should be understood that, for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationship.

[0024] The following description of at least one exemplary embodiment is merely illustrative in nature and in no way serves as a limitation to the present disclosure and its application or use.

[0025] Technologies, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods and devices should be regarded as part of the authorization specification.

[0026] In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0027] It should be noted that: like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0028] To make the purpose, technical solutions and advantages of the present disclosure more clear and understandable, the present disclosure will be further described in detail below with reference to specific embodiments and the accompanying drawings.

[0029] Figure 1 Schematic diagram of some embodiments of the current limiter of the present disclosure. The current limiter is an electronic current limiter, including a sampling circuit 110, a switching circuit 120 and a control circuit 130.

[0030] The first end of the sampling circuit 110 is connected to the first end of the current limiter, and the second end of the sampling circuit 110 is connected to the first end of the switching circuit 120. The second end of the switching circuit 120 is connected to the second end of the current limiter 1. The first end of the control circuit 130 is respectively connected to the first end and the second end of the sampling circuit 110, and the second end of the control circuit 130 is connected to the control end of the switching circuit 120.

[0031] In some embodiments, the voltage at the first end of the switch circuit 120 is higher than the voltage at the second end of the switch circuit 120.

[0032] The sampling circuit 110 is configured to sample the voltage and current in the DC line. The control circuit 130 is configured to output a pulse signal to the switch circuit 120 according to the sampling result of the sampling circuit 110 to control the switching speed of the switch circuit 120.

[0033] In some embodiments, the current limiter is disposed in the DC system. For example, the first end of the current limiter is connected to the DC power supply, and the second end of the current limiter is connected to DC electrical equipment, energy storage equipment, etc.

[0034] In some embodiments, according to the sampling result, it is possible to determine whether the DC line is abnormal. If the DC line is abnormal, the larger the current in the DC line, the smaller the duty cycle of the pulse signal. For example, during the normal charge and discharge process of the energy storage equipment, an abnormal situation such as a short circuit occurs on the high-voltage side, resulting in an instantaneous excessive current on the high-voltage side. Through the sampling circuit, it is determined that the high-voltage side is abnormal. By reducing the duty cycle of the pulse signal, the switching speed of the switch circuit can be controlled to slow down, reducing the energy input to the user equipment, thereby reducing the current on the high-voltage side.

[0035] In some embodiments, if the current in the DC circuit is greater than the threshold, the duty cycle of the pulse signal is set to 0, thereby controlling the switch circuit 120 to be in an off state, that is, disconnecting the connection between the DC power supply and the equipment to protect the safety of the equipment.

[0036] In the above embodiments, by providing the sampling circuit, the switch circuit, and the control circuit, when the DC line is abnormal, a pulse signal can be output to the switch circuit to control the switching speed of the switch circuit, thereby reducing the DC line current and keeping the DC line current stable within the normal operating range.

[0037] In some other embodiments of the present disclosure, the control circuit 130 is further configured to output a pulse signal to the switch circuit 120 when receiving any one of the charging instruction and the discharging instruction to control the switching speed of the switch circuit 120. When the control circuit 130 receives the charging instruction or the discharging instruction, it activates the current limiter. By controlling the switching speed, the current in the DC line can be controlled within a certain threshold to ensure the stability of the DC line current.

[0038] In some embodiments of the present disclosure, as Figure 2 shown, the sampling circuit 110 includes a sampling resistor 111, which mainly provides sampling of the DC line voltage and current. Since the current in the DC line is large, requirements are imposed on the internal resistance, temperature drift, and accuracy of the sampling resistor. For example, it is required to have a small internal resistance, a small temperature drift, and a high accuracy.

[0039] In some embodiments of the present disclosure, as Figure 2 shown, the switching circuit 120 includes an inductor 121 and a first switch 122. The first end of the inductor 121 is connected to the first end of the current limiter 1, the first end of the first switch 122 is connected to the second end of the inductor 121, the second end of the first switch 122 is connected to the second end of the current limiter 1, and the control end of the first switch 122 is connected to the second end of the control circuit 130.

[0040] In some embodiments, when the power load is overloaded, overcurrent, or short-circuited, the inductor 121 can play a buffering role to prevent the current from being instantaneously increased and causing circuit damage. The first switch 122 controls the switching of the high-voltage DC line.

[0041] In some embodiments, the first switch 122 is a MOS (Metal-Oxide-Semiconductor) transistor. The first end of the MOS transistor is, for example, the drain, the second end is the source, and the control end is the gate. This MOS is a high-voltage MOS transistor, such as a PMOS or an NMOS. In some embodiments, the first switch 122 is an IGBT (Insulated Gate Bipolar Transistor).

[0042] In some embodiments, the switching circuit 120 further includes a diode 123. The anode of the diode 123 is connected to the first end of the first switch 122, and the cathode of the diode 123 is connected to the second end of the first switch 122. This diode 123 is a high-current diode, and in the normal operating state, it plays a role in shunting the first switch 122 and reducing the current of the first switch 122.

[0043] In some embodiments, when charging the device, the diode 123 conducts forwardly and can play a role in shunting the first switch 122. When the device discharges, since the external discharge is a slow process, therefore, in normal discharge, there will be no large current on the high-voltage side. And in the event of an abnormality such as a short circuit, although the diode 123 is in the cut-off state, it reduces the switching speed of the first switch 122, and finally causes the first switch 122 to turn off. Therefore, it can also maintain the stability of the power system.

[0044] In some embodiments, the switching circuit 120 further includes a lightning protection tube 124. The first end of the lightning protection tube 124 is connected to the first end of the first switch 122, and the second end of the lightning protection tube 124 is connected to the second end of the first switch 122. The lightning protection tube 124 can absorb high-frequency high-voltage pulse voltage signals to prevent the high-frequency voltage generated by the first switch 122 during high-frequency switching from damaging circuit components.

[0045] In some other embodiments of the present disclosure, asFigure 2 As shown, the control circuit 130 includes: a current acquisition circuit 131, a voltage acquisition circuit 132, a monitoring chip 133, a controller 134, and a pulse output circuit 135.

[0046] The current acquisition circuit 131 is respectively connected to the first end and the second end of the sampling circuit 110, the voltage acquisition circuit 132 is respectively connected to the first end and the second end of the sampling circuit 110, the monitoring chip 133 is respectively connected to the current acquisition circuit 131 and the voltage acquisition circuit 132, the controller 134 is connected to the monitoring chip 133, and the pulse output circuit 135 is connected to the controller 134.

[0047] The current acquisition circuit 131 is configured to acquire the current value sampled by the sampling circuit 110. In some embodiments, the current acquisition circuit 131 performs differential sampling on the voltage across the sampling circuit, including filtering, signal amplification, and isolation, then acquires the DC line current value, and inputs the current value to the monitoring chip 133.

[0048] The voltage acquisition circuit 132 is configured to acquire the voltage value sampled by the sampling circuit 110. In some embodiments, the voltage acquisition circuit 132 samples the voltage of the sampling circuit, including filtering, signal amplification, and isolation, then acquires the DC line voltage value, and inputs the voltage value to the monitoring chip 133.

[0049] The monitoring chip 133 is configured to perform arithmetic processing on the current value and the voltage value, such as performing an AND operation on the current value and the voltage value. In some embodiments, if it is true that the current value does not exceed the current threshold and it is also true that the voltage value does not exceed the voltage threshold, then through the AND operation, the output result is true, and at this time the DC line is normal. If the current value exceeds the current threshold or the voltage value exceeds the voltage threshold, or, the current value exceeds the current threshold and the voltage value also exceeds the voltage threshold at the same time, then through the AND operation, the output result is false, and at this time the DC line is abnormal.

[0050] In some other embodiments of the present disclosure, the power and power consumption data can also be calculated based on the current value and the voltage value of the DC line, and then it is determined whether the DC line is abnormal.

[0051] The controller 134 is configured to determine whether the DC line is abnormal according to the output result of the monitoring chip. If it is abnormal, it outputs the duty cycle information of the pulse signal to the pulse output circuit 135. The controller 134 controls the operation of the entire current limiter. When the DC line is abnormal, it adjusts the duty cycle of the pulse signal, and then adjusts the switching rate of the switching circuit 120 to make the DC line stable.

[0052] The pulse output circuit 135 is configured to generate a pulse signal with duty cycle information and send the pulse signal to the switching circuit 120.

[0053] In some embodiments, the MOS transistor is controlled by a PWM square wave to control the DC line current within a certain threshold. After maintaining for a certain period of time, the MOS transistor switch is turned on, and the DC line current is continuously monitored. If a current exceeding the set threshold is still detected, the PWM square wave control is continuously output; otherwise, the MOS transistor switch is turned off.

[0054] In the above embodiments, by detecting the voltage and current of the DC line, when it is determined that the DC line is abnormal, the control circuit controls the switching speed of the switching circuit by outputting a pulse signal, so that when an overcurrent, overload, or short circuit occurs in the equipment or energy storage on the DC line, the DC line current can still be stabilized within the normal operating range, improving the stability of the power system.

[0055] In some other embodiments of the present disclosure, the control circuit 130 further includes a communication circuit 136 connected to the controller 134. Among them, the controller 134 receives any one of the charging instruction and the discharging instruction through the communication circuit 136. The communication circuit is, for example, a common industrial communication bus circuit such as RS485 or CAN. When the controller 134 receives a normal charging or discharging instruction, it controls the pulse output circuit 135 to output a pulse signal to control the switching rate of the switching circuit 120. The switching speed of the switching circuit 120 when the DC line is normal is different from the switching speed of the switching circuit 120 when the DC line is abnormal.

[0056] In some embodiments of the present disclosure, a power system is protected. The power system includes the above-mentioned current limiter. One end of the current limiter can be connected to an energy storage device or an electrical device, and the other end is connected to a DC power supply. The DC power supply referred to here can be a DC power supply terminal after DC / DC conversion or AC / DC conversion.

[0057] In some embodiments, as Figure 3 shown, one end of the current limiter 1 is connected to the energy storage device 2, and the other end is connected to the DC power supply 3. The voltage at the first end of the switching circuit 120 of the current limiter 1 is higher than the voltage at the second end of the switching circuit 120. When the energy storage device 2 is charging, the current is input from the high-voltage side and output from the low-voltage side. When the energy storage device discharges externally, the current is input from the low-voltage side and output from the high-voltage side.

[0058] In this embodiment, setting a current limiter in the power system can effectively protect the power supply system and equipment, and ensure the normal operation of the power supply system and protect the electrical equipment from being burned out in case of overcurrent or short circuit.

[0059] So far, the present disclosure has been described in detail. To avoid obscuring the concept of the present disclosure, some details well known in the art have not been described. Those skilled in the art can fully understand how to implement the technical solutions disclosed here based on the above description.

[0060] The methods and apparatuses of the present disclosure may be implemented in many ways. For example, the methods and apparatuses of the present disclosure may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The above order of the steps for the method is for illustrative purposes only. The steps of the method of the present disclosure are not limited to the specific order described above, unless otherwise specifically stated. In addition, in some embodiments, the present disclosure may also be implemented as a program recorded in a recording medium, and these programs include machine-readable instructions for implementing the method according to the present disclosure. Therefore, the present disclosure also covers a recording medium storing a program for executing the method according to the present disclosure.

[0061] Although some specific embodiments of the present disclosure have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and not for limiting the scope of the present disclosure. Those skilled in the art should understand that the above embodiments may be modified without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

1. A current limiter, comprising: A sampling circuit, the first end of which is connected to the first end of the current limiter and is configured to sample the voltage and current in a DC line; A switching circuit, the first end of which is connected to the second end of the sampling circuit, and the second end of which is connected to the second end of the current limiter; And A control circuit, comprising: A current acquisition circuit configured to acquire the current value sampled by the sampling circuit; A voltage acquisition circuit configured to acquire the voltage value sampled by the sampling circuit; A monitoring chip, connected to the current acquisition circuit and the voltage acquisition circuit respectively, and configured to perform arithmetic processing on the current value and the voltage value; A controller, connected to the monitoring chip, and configured to determine whether the DC line is abnormal according to the output result of the monitoring chip. If it is abnormal, the duty cycle information of a pulse signal is output to a pulse output circuit; and A pulse output circuit, connected to the controller, and configured to generate a pulse signal with the duty cycle information and send the pulse signal to the switching circuit to control the switching speed of the switching circuit.

2. The current limiter according to claim 1, wherein The control circuit is further configured to output a pulse signal to the switching circuit to control the switching speed of the switching circuit when receiving any one of a charging instruction and a discharging instruction.

3. The current limiter according to claim 1, wherein If the DC line is abnormal, the greater the current in the DC line, the smaller the duty cycle of the pulse signal.

4. The current limiter according to claim 1, wherein The voltage at the first end of the switching circuit is higher than the voltage at the second end of the switching circuit.

5. The current limiter according to claim 1, wherein, The switching circuit includes: An inductor, the first end of which is connected to the first end of the current limiter; and A first switch, the first end of which is connected to the second end of the inductor, the second end of which is connected to the second end of the current limiter, and the control end of which is connected to the second end of the control circuit.

6. The current limiter according to claim 5, wherein, The switching circuit further includes: A diode, the anode of which is connected to the first end of the first switch, and the cathode of which is connected to the second end of the first switch.

7. The current limiter according to claim 6, wherein, The switching circuit further includes: A lightning protection tube, the first end of which is connected to the first end of the first switch, and the second end of which is connected to the second end of the first switch.

8. The current limiter according to any one of claims 1 to 6, wherein The control circuit further includes: A communication circuit connected to the controller, wherein the controller receives any one of a charging instruction and a discharging instruction through the communication circuit.

9. A power system, comprising the current limiter according to any one of claims 1 to 8.

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