Relay drive control circuit, method and photovoltaic energy storage system

Abstract

The present application provides a relay drive control circuit and a photovoltaic energy storage system, wherein the relay drive control circuit includes: a control unit, an adjustable power supply unit, a negative pressure supply unit and a switch unit, the control unit is electrically connected to the first end of the adjustable power supply unit and the switch unit respectively, the negative pressure supply circuit is electrically connected to the second end of the adjustable power supply unit and is used to be electrically connected to an external relay unit, and the second end of the switch unit is used to be electrically connected to the relay unit. When the present application turns off the relay, the control unit first controls the adjustable power supply unit to turn off the voltage output, at which time the negative pressure supply unit will provide a negative voltage to both ends of the relay coil, and this negative voltage is superimposed on the positive voltage of the relay coil to reduce the voltage at both ends of the relay coil to a preset value, such as 0V, so as to offset the residual energy in the coil, and then disconnect the switch unit, so as to achieve the purpose of rapid disconnection of the relay while avoiding the coil induced voltage from damaging the switch unit.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a relay drive control circuit, method and photovoltaic energy storage system. Background Art

[0002] In relay applications, semiconductor switching devices are usually used to control the on and off of the relay coil current, thereby allowing the coil to generate magnetism and make the relay contacts close and open. Since the relay coil has an inductive property, there will still be an induced electromotive force when the relay coil path is disconnected, and its voltage amplitude may even be dozens of times the coil supply voltage, which places strict requirements on the withstand voltage of the semiconductor switching device.

[0003] At present, the method commonly used to solve this problem is: when the relay coil circuit is disconnected, a freewheeling circuit is provided to the coil, in which the energy in the coil is consumed to avoid the high induced voltage generated by the too fast current change rate in the coil at the moment of relay disconnection, which damages the semiconductor switch device, thereby achieving the purpose of protecting the semiconductor switch device. However, the freewheeling circuit will bring another problem: although the semiconductor switch device that controls the on and off of the relay coil is disconnected, the freewheeling circuit provides another closed path for the relay coil, which allows the relay coil to continue to work, causing the relay contacts to remain connected until the energy in the coil is insufficient to maintain the contact pull-in energy to truly disconnect the contacts. Therefore, there will be a long shutdown delay problem, and this delay time may be tens of milliseconds or even hundreds of milliseconds, which will affect the function of the product in some applications. Summary of the invention

[0004] The main purpose of the present application is to provide a relay drive control circuit, method and photovoltaic energy storage system, which can at least solve the problem in the related art that the product-related functions cannot be realized or even the product may be damaged due to the long off-time of the relay.

[0005] To achieve the above-mentioned purpose, the first aspect of the present application provides a relay drive control circuit, including: a control unit, an adjustable power supply unit, a negative pressure supply unit and a switch unit, the control unit is electrically connected to the first ends of the adjustable power supply unit and the switch unit respectively, the negative pressure supply circuit is electrically connected to the second end of the adjustable power supply unit and is used to be electrically connected to an external relay unit, and the second end of the switch unit is used to be electrically connected to the relay unit; the adjustable power supply unit is used to: stop outputting a driving voltage to the relay unit when receiving a first shutdown control signal transmitted by the control unit; the negative pressure supply unit is used to: output a negative voltage to the relay unit when the adjustable power supply unit is in a shutdown state; the control unit is used to: output a second shutdown control signal to the switch unit when the voltage of the relay coil in the relay unit is reduced to a preset value; the switch unit is used to: enter a cut-off state when receiving the second shutdown control signal to control the relay unit to enter a shutdown state.

[0006] The second aspect of the present application provides a relay drive control method, which is applied to the relay drive control circuit as described in the first aspect of the present application, including: when the adjustable power supply unit receives the first shutdown control signal transmitted by the control unit, the adjustable power supply unit stops outputting the drive voltage to the relay unit; when the adjustable power supply unit is in the shutdown state, the negative pressure supply unit outputs a negative voltage to the relay unit; when the voltage of the relay coil in the relay unit is reduced to a preset value, the control unit outputs a second shutdown control signal to the switch unit; when the switch unit receives the second shutdown control signal, it enters the cut-off state to control the relay unit to enter the shutdown state.

[0007] A third aspect of the present application provides a photovoltaic energy storage system, including a relay unit and a relay drive control circuit as described in the first aspect of the present application.

[0008] From the above description, it can be known that when the relay needs to be turned off, the control unit first sends a shutdown control signal to the adjustable power supply unit to turn off the voltage output of the adjustable power supply unit. At this time, the negative voltage supply unit will provide a negative voltage to both ends of the relay coil. Since this negative voltage is opposite to the voltage direction of the normal operation of the relay coil, the two voltages are superimposed to reduce the voltage at both ends of the relay coil to 0V, thereby offsetting the residual energy in the coil. After that, the control unit disconnects the control switch of the relay coil, thereby achieving rapid disconnection of the relay while avoiding the induced voltage of the relay coil from damaging the switching device. In addition, the present application does not need to add a freewheeling circuit. In application scenarios with a large number of relays, the drive control circuit can effectively simplify the structure of the system circuit and save design costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0010] Figure 1 is a structural schematic diagram of a relay drive control circuit according to an embodiment of the present application; Figure 2 is a circuit schematic diagram of a first relay drive control circuit according to an embodiment of the present application; Figure 3 is a circuit schematic diagram of a second relay drive control circuit according to an embodiment of the present application; Figure 4 is a circuit schematic diagram of a third relay drive control circuit of an embodiment of the present application; Figure 5 is a circuit schematic diagram of a fourth relay drive control circuit of an embodiment of the present application; Figure 6 It is a basic flow chart of a relay drive control method according to an embodiment of the present application. DETAILED DESCRIPTION

[0011] In order to make the purpose, features, and advantages of the invention of this application more obvious and easy to understand, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.

[0012] In the related art, in order to quickly release the energy on the relay coil, a resistor is usually connected in series in the traditional diode freewheeling circuit. In this way, after the relay coil circuit is disconnected, the freewheeling circuit continues to provide a conduction path for the relay coil, so that the coil current returns to the coil through the diode and the resistor. The freewheeling current will generate heat on the resistor and lose energy. This part of the loss plays a role in accelerating the discharge of coil energy. Compared with the traditional freewheeling circuit with only a diode, this method shortens the time for the relay coil to release energy and can reduce the relay shutdown time to a certain extent. However, there are still the following disadvantages: it still essentially requires a relay freewheeling circuit, but it increases the energy discharge load, but the coil energy consumption still requires a certain amount of time, and the resistor added to the circuit increases the loss of the entire product and reduces the product efficiency. To this end, the embodiment of the present application provides a relay drive control circuit.

[0013] like Figure 1 The figure shows a structural schematic diagram of a relay drive control circuit provided in an embodiment of the present application, wherein the relay drive control circuit includes: a control unit 100, an adjustable power supply unit 200, a negative pressure supply unit 300 and a switch unit 400, wherein the control unit 100 is electrically connected to the first ends of the adjustable power supply unit 200 and the switch unit 400, respectively, the negative pressure supply circuit is electrically connected to the second end of the adjustable power supply unit 200 and is used to be electrically connected to an external relay unit 500, and the second end of the switch unit 400 is used to be electrically connected to the relay unit 500.

[0014] Among them, the adjustable power supply unit 200 is used to: stop outputting the driving voltage to the relay unit 500 when receiving the first shutdown control signal transmitted by the control unit 100; the negative pressure supply unit 300 is used to: output a negative voltage to the relay unit 500 when the adjustable power supply unit 200 is in the shutdown state; the control unit 100 is used to: when the voltage of the relay coil in the relay unit 500 is reduced to a preset value, output a second shutdown control signal to the switch unit 400; the switch unit 400 is used to: when receiving the second shutdown control signal, enter the cut-off state to control the relay unit 500 to enter the shutdown state.

[0015] It should be noted that according to the working principle of the relay, a voltage higher than the starting voltage needs to be applied to the relay coil in the early stage of the relay closing in order to close the relay. Generally, in order to reliably close the relay and speed up the closing speed, the rated voltage of the coil voltage is used as the starting voltage. For example, a coil relay with a rated voltage of 12V usually applies a voltage of 12Vdc or 14Vdc or higher to the relay to close the relay. If the relay coil is always supplied with a 12V power supply voltage, long-term operation will cause large coil losses and an increase in the overall temperature of the relay. However, according to the working principle of the relay, after the relay is closed, the coil maintenance voltage can generally be reduced to 50% of the rated voltage of the coil, thereby reducing the coil loss and increasing the system efficiency while maintaining the normal closure of the relay. When the loss of the relay coil is reduced, the temperature rise of the relay will also decrease, which allows the relay to adapt to higher ambient temperatures.

[0016] In photovoltaic inverters or energy storage systems, there will be switching between grid connection and off-grid connection, and this switching only relies on different control loops to realize the disconnection and closing of the relay. The existence of a relay coil freewheeling loop in the current general relay drive control scheme will slow down the disconnection speed of the relay and affect the switching between grid connection and off-grid connection. Therefore, in this embodiment, before disconnecting the relay, the voltage maintained by the relay coil has dropped to 50% of the rated voltage. The output of the adjustable power supply unit 200 is turned off by the control unit 100. At this time, the negative voltage supply circuit will generate a negative voltage to provide to the relay unit 500. The negative voltage is superimposed on the positive voltage on the relay coil, so that the voltage of the relay coil decreases rapidly, and can even be reduced to 0V, thereby quickly offsetting the residual energy in the coil. After that, the control switch of the relay coil is disconnected by the control unit 100, thereby realizing the rapid disconnection of the relay and avoiding the induced voltage of the relay coil from damaging the switch device. In addition, the present application does not need to add a freewheeling loop. In application scenarios with a large number of relays, the drive control circuit can effectively simplify the structure of the system circuit and save design costs.

[0017] like Figure 2 , Figure 3 The schematic diagrams of the first relay drive control circuit and the second relay drive control circuit provided in this embodiment are shown in FIG. Figure 2 and Figure 3 The negative pressure supply unit 300 includes a voltage regulator tube ZD1, a capacitor unit and a first resistor R1; the cathode of the voltage regulator tube ZD1 is electrically connected to one end of the first resistor R1 and the first end of the capacitor unit, the anode of the voltage regulator tube ZD1 is grounded, the other end of the first resistor R1 is electrically connected to the second end of the adjustable power supply unit 200 and is used to be electrically connected to the relay unit 500, the first end of the capacitor unit is also electrically connected to the switch unit 400, the second end of the capacitor unit is electrically connected to the second end of the adjustable power supply unit 200 and is used to be electrically connected to the relay unit 500, and the third end of the capacitor unit is grounded.

[0018] Furthermore, the capacitor unit includes a first capacitor C1, a second capacitor C2 and a third capacitor C3; one end of the first capacitor C1 and the second capacitor C2 are electrically connected to the second end of the adjustable power supply unit 200, the other end of the first capacitor C1 is grounded, the other end of the second capacitor C2 is electrically connected to one end of the third capacitor C3, the cathode of the voltage regulator ZD1 and the switch unit 400, respectively, and the other end of the third capacitor C3 is grounded.

[0019] Specifically, in this embodiment, the negative pressure supply circuit includes a voltage regulator tube ZD1 and a resistor and capacitor device, wherein the capacitor can be used to store energy to stabilize the voltage, and the resistor can be used to limit the current to ensure that the voltage regulator tube ZD1 works in a safe area. The voltage regulator tube ZD1 is used to divide the total output voltage of the adjustable power supply unit 200 into two parts, one part of the voltage is the voltage regulation value of the voltage regulator tube ZD1, and the other part of the voltage is the output voltage of the adjustable power supply unit 200 minus the voltage regulation value of the voltage regulator tube ZD1 (the principle of selecting the voltage regulator tube ZD1 is that the voltage regulation value is less than the starting voltage of the relay. In this embodiment, the voltage regulator tube ZD1 with a voltage regulation value of 50% of the rated voltage of the relay coil is selected). When the relay unit 500 needs to be turned off, the output of the adjustable power supply unit 200 is turned off through the control unit 100. At this time, the output positive pole of the adjustable power supply unit 200 is 0V to the ground GND, and the voltage of the second reference ground GND_2 to the ground is the voltage value of the voltage regulator ZD1 (assuming it is 6V), then the voltage of GND to the second reference ground GND_2 is -6V, so the output positive pole of the adjustable power supply unit 200 is -6V to the second reference ground, and the output positive pole of the adjustable power supply unit 200 is connected to one end of the relay coil, and the second reference ground GND_2 is connected to one end of the relay control switch. At this time, the two ends of the relay coil are equivalent to adding a -6V negative voltage to the original 6V voltage, so that the voltage at both ends of the relay coil is 0V or a negative value after superposition, and then the switch unit 400 in the relay coil loop is disconnected. At this time, although there is no freewheeling circuit on the relay coil, the positive voltage is offset by a negative voltage, consuming the residual energy in the relay coil. When the coil impedance remains unchanged, the coil current is very small at this time. According to the relationship between the voltage and current of the inductor element It can be seen that, when the coil impedance L and time dt remain unchanged, the decrease in current di will cause the coil induced voltage U to decrease exponentially at the same time, and a negative voltage will be superimposed at the same time, so the voltage value of the induced voltage U generated at this time to the second reference ground GND_2 is much smaller than the withstand voltage of the switch unit 400. Therefore, the disconnection speed of the relay under the control scheme of this embodiment is significantly improved, and the relay coil loss can be effectively reduced and the product stability can be improved.

[0020] like Figure 4 The third relay drive control circuit provided in this embodiment is shown in FIG. Figure 4The adjustable power supply unit 200 includes an adjustable power supply chip 210, an enabling control unit 220 and a feedback voltage regulating unit 230; the first end of the adjustable power supply chip 210 is electrically connected to one end of the enabling control unit 220, the second end of the adjustable power supply chip 210 is electrically connected to the negative pressure supply unit 300 and the first end of the feedback voltage regulating unit 230 respectively, the third end of the adjustable power supply chip 210 is electrically connected to the second end of the feedback voltage regulating unit 230, the other end of the enabling control unit 220 is electrically connected to the control unit 100, and the third end of the feedback voltage regulating unit 230 is electrically connected to the control unit 100. The control unit 100 in this embodiment may be an MCU.

[0021] For further information, see Figure 4 The feedback voltage regulating unit 230 includes a second resistor R2, a third resistor R3 and at least one resistance selecting unit, one end of the second resistor R2 is electrically connected to the second end of the adjustable power chip 210, the other end of the second resistor R2 is electrically connected to one end of the third resistor R3, one end of the resistance selecting unit and the third end of the adjustable power chip 210 respectively, the other end of the third resistor R3 is grounded, and the other end of the resistance selecting unit is grounded.

[0022] Further, see Figure 4 The resistance selection unit includes a fourth resistor R4 and a first switch device Q1, one end of the fourth resistor R4 is electrically connected to the other end of the second resistor R2, the other end of the fourth resistor R4 is electrically connected to the first end of the first switch device Q1, the second end of the first switch device Q1 is electrically connected to the control unit 100, and the third end of the first switch device Q1 is grounded. In this embodiment, the first switch device Q1 can be a triode or a MOS tube, and the control unit 100 can be an MCU.

[0023] Specifically, in this embodiment, the feedback voltage adjustment unit 230 may include one or more resistance selection units. By controlling the first switch device Q1 to enter different operating states, different numbers of resistors can be connected to the voltage divider circuit, thereby obtaining different voltage feedback values, and transmitting the voltage feedback value to the adjustable power supply unit 200. After receiving the voltage feedback value, the adjustable power supply unit 200 can adjust the voltage value transmitted to the relay unit 500 through the internal control logic, thereby realizing the adjustment of the relay power supply voltage value. Figure 4Taking the structure of the feedback voltage regulating unit 230 in the example, by controlling the conduction state of the first switch device Q1 by the control unit 100, the switching of the two power supply voltages can be realized. For example, when the first switch device Q1 is controlled to enter the conduction state, the resistors R3 and R4 are connected in parallel to form a parallel resistor, and the voltage output by the adjustable power supply unit 200 will be sent to the voltage feedback terminal Vsense of the adjustable power supply unit 200 after voltage division by the resistor R2 and the parallel resistor. At this time, the adjustable power supply unit 200 will adjust the output voltage to a voltage value V1 corresponding to the feedback voltage value according to the voltage feedback value; when the first switch device Q1 is controlled to be disconnected, only the resistor R3 is involved in the lower voltage dividing resistor for voltage sampling. At this time, the output voltage is transmitted to the voltage feedback terminal Vsense of the adjustable power supply unit 200 after voltage division by the resistors R2 and R3. At this time, the adjustable power supply unit 200 will adjust the output voltage to the corresponding voltage value V2.

[0024] Therefore, this embodiment can adjust the supply voltage of the relay coil by controlling the first switch device Q1. Compared with the traditional coil voltage switching solution (which requires the design of two power supplies and corresponding switching control circuits, and when there are many relays, the control is complex and occupies more software and hardware resources), it requires fewer resources and lower costs, and has the advantages of simple structure and high product stability.

[0025] In this embodiment, by connecting resistors at both ends of the switch device, the stability of the switch device control can be improved. For example, when the switch device is a triode, connecting a resistor at the base of the triode helps to limit the current from the input signal source, thereby stably controlling the working state of the triode. By adjusting the value of the base resistor, the degree of influence of the input signal on the output signal can also be controlled; and by connecting a resistor at the emitter, current feedback can be provided to stabilize the output. In addition, the connected resistor can also limit the current and protect the switch device from damage by excessive current. By appropriately adjusting the value of the connected resistor, the output current can be controlled within a safe range; it can also reduce line noise interference and improve the purity and reliability of the signal.

[0026] For further information, see Figure 4 , the enabling control unit 220 includes a fifth resistor R5, a sixth resistor R6 and a second switch device Q2, one end of the fifth resistor R5 is electrically connected to the fourth end of the adjustable power supply chip 210, the other end of the fifth resistor R5 is electrically connected to one end of the sixth resistor R6, the first end of the adjustable power supply chip 210, and the first end of the second switch device Q2, respectively, the other end of the sixth resistor R6 is grounded, the second end of the second switch device Q2 is electrically connected to the control unit 100, and the third end of the second switch device Q2 is grounded.

[0027] Specifically, in the present embodiment, the adjustable power supply unit 200 has an output voltage feedback regulation function, and a circuit or integrated power supply chip with output voltage feedback regulation such as a Buck step-down DC-DC power supply chip, a linear regulated DC power supply IC with adjustable ADJ, and an adjustable LDO chip can be selected. Taking the Buck step-down DC-DC power supply chip as an example, the output is turned off when the enable terminal EN of the Buck power supply chip is at a low level, so the Buck power supply chip can be turned on and off by the enable control unit 220. For example, when the second switch device Q2 is turned off, the input voltage is divided into a voltage value through a voltage divider resistor and connected to the enable pin in the adjustable power supply chip 210 to make it at a high level. At this time, the Buck power supply chip is in an on state. When the second switch device Q2 is turned on, the enable pin of the adjustable power chip 210 is pulled to a low level, and the Buck power chip is in a closed state. At this time, a negative voltage is added to both ends of the relay coil through the negative voltage supply circuit, and then the control unit 100 is used to control the switch unit 400 to disconnect. Due to the effect of the coil negative pressure, the coil energy and the voltage value at both ends are offset, and finally the relay contacts are quickly disengaged. In addition, similar to the first switch device Q1, a resistor can also be connected to the base or gate, emitter or source of the second switch device Q2 to ensure the stability of the switch device control.

[0028] For further information, see Figure 4 The switch unit 400 includes at least one third switch device Q3, a first end of the third switch device Q3 is used to be electrically connected to a corresponding relay in the relay unit 500, a second end of the third switch device Q3 is electrically connected to the control unit 100, and a third end of the third switch device Q3 is electrically connected to the negative pressure supply unit 300. When the application scenario is multiple relays, there are multiple third switch devices Q3n in the relay unit 500, Q3n is electrically connected to the control unit 100, and the opening and closing of multiple relays are controlled by the control unit 100. Specifically, in this embodiment, since the Buck power chip has a strong output load capacity and the load current can be as high as several amperes, it can carry multiple coil relays. A corresponding number of third switch devices Q3 can be set according to the number of relays in the relay unit 500, for example Figure 4 , Figure 5 The on and off of multiple relays can be controlled by the third switch device Q3.

[0029] Furthermore, the relay unit 500 further includes at least one overvoltage protection circuit, which is electrically connected to the corresponding third switching device Q3.

[0030] Specifically, the overvoltage protection circuit includes a zener diode, a cathode of the zener diode is electrically connected to the first end of the third switch device Q3, and an anode of the zener diode is electrically connected to the third end of the third switch device Q3.

[0031] In this embodiment, in order to ensure the safety of the third switch device Q3, a protection measure can also be set for the third switch device Q3, such as designing an overvoltage protection structure to prevent the input voltage from exceeding the set range, and a voltage regulator diode can be used for overvoltage protection. In addition, a combination structure such as a capacitor and a resistor can be used to limit the current and reduce the voltage to protect the device. In addition to the overvoltage protection structure, measures such as overcurrent protection and overtemperature protection can also be designed according to actual needs to ensure that the switch device of the control relay can work stably and reliably and extend its service life.

[0032] The relay drive control circuit provided in the embodiment of the present application controls the feedback voltage regulation unit and the enabling control unit through the control unit. By closing and opening the internal switching device of the feedback voltage regulation unit, different sampling resistor combinations suitable for different output voltages can be obtained. The adjustable power supply unit can adjust different output voltages according to the voltage feedback value transmitted by the feedback voltage regulation unit. When the relay needs to be turned off, the output voltage of the adjustable power supply unit is first turned off by the enabling control unit, and the negative pressure supply unit is used to construct a negative voltage to be added to both ends of the relay coil to offset the positive voltage of the coil and the stored energy, and then further turn off the switching device of the control relay coil. Finally, the safety of the switching device of the control relay is guaranteed, and at the same time, the shutdown delay of the relay can be effectively reduced, and the device loss is reduced. The control circuit has the advantages of simple circuit structure and low design cost.

[0033] The embodiment of the present application also provides a relay drive control method, which is applied to the above relay drive control circuit, such as Figure 6 The figure shows a basic flow chart of a relay drive control method provided by this embodiment, and the relay drive control method comprises the following steps: Step 601: When the adjustable power supply unit receives a first shutdown control signal transmitted by a control unit, the adjustable power supply unit stops outputting a driving voltage to the relay unit.

[0034] In some embodiments, when the adjustable power supply unit is not turned off, the control unit controls the corresponding first switching device in the adjustable power supply unit to enter the target operating state according to the preset target output voltage value. The process is specifically as follows: the control unit compares the target output voltage value with the preset voltage threshold; when the target output voltage value is less than the voltage threshold, the control unit queries the sampling resistance value corresponding to the target output voltage value based on the preset resistance index table, determines the corresponding target switching device according to the sampling resistance value, and controls the target switching device to enter the cut-off state; wherein the resistance index table includes the mapping relationship between the target output voltage value, the feedback resistance value obtained by the parallel combination of resistors, and the first switching device.

[0035] Then, the feedback voltage regulation unit will output the corresponding voltage feedback value to the adjustable power supply chip according to the target operating state of the first switching device. The specific process is as follows: the feedback voltage regulation unit calculates the voltage feedback value according to the connected resistor and the voltage value currently output by the adjustable power supply chip, and transmits the voltage feedback value to the adjustable power supply chip; wherein the connected resistor includes resistor R2 and a lower voltage divider resistor, the lower voltage divider resistor includes a combined resistor of resistors R3 and R4 or only resistor R3, and the voltage feedback value is the voltage difference across the lower voltage divider resistor.

[0036] After obtaining the voltage feedback value, the adjustable power chip will adjust the amplitude of the output voltage transmitted to the relay unit according to the voltage feedback value and the reference voltage. Among them, the adjustable power chip has a reference voltage. When the voltage feedback value transmitted by the feedback voltage adjustment unit is not equal to the reference voltage, the adjustable power chip will adjust the output voltage so that the voltage feedback value output by the feedback voltage adjustment unit remains near the reference voltage value. For example, when the voltage feedback value is higher than the reference voltage feedback value, the adjustable power chip will adjust the output duty cycle to reduce the output voltage. It should be noted that the voltage value output to the negative voltage supply circuit and the relay unit should be greater than or equal to the reference voltage of the adjustable power chip to ensure that the voltage feedback value can be adjusted to the reference voltage value.

[0037] Step 602: When the adjustable power supply unit is in the off state, the negative pressure supply unit outputs a negative voltage to the relay unit; Step 603: When the voltage of the relay coil in the relay unit decreases to a preset value, the control unit outputs a second shutdown control signal to the switch unit; Step 604: When receiving the second shutdown control signal, the switch unit enters the cut-off state to control the relay unit to enter the shutdown state.

[0038] Specifically, in this embodiment, when the control unit sends a control signal to turn off the output to the adjustable power supply unit, the adjustable power supply unit turns off the output, and at this time the negative voltage supply unit constructs a negative voltage to be loaded on both ends of the relay coil to offset the positive voltage and residual energy of the coil. When the voltage at both ends of the relay coil drops to a negative voltage at the positive pole of the voltage relative to the second reference ground GND_2, the switch device that controls the relay coil is disconnected by the control switch. At this time, the energy in the relay coil is very low and the voltage difference at both ends of the coil is small. Because the relay does not have a freewheeling circuit, the relay contacts can be quickly disconnected, and the induced voltage generated by the coil is much smaller than the withstand voltage of the semiconductor switch device, ensuring the safety of the semiconductor device.

[0039] The embodiment of the present application also provides a photovoltaic energy storage system, which includes a relay unit and the above-mentioned relay drive control circuit.

[0040] It should be noted that the various embodiments in the present application are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0041] It should also be noted that, in the content of the present application, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first" and "second" can expressly or implicitly include one or more of the features. In the description of the embodiments of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. The terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements that are not clearly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements defined by the sentence "include one..." do not exclude the presence of other identical elements in the process, method, article or equipment including the elements.

[0042] The above description of the disclosed embodiments enables professionals and technicians in the field to implement or use the present application. Various modifications to these embodiments will be apparent to professionals and technicians in the field, and the general principles defined in the present application can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown in the present application, but will conform to the widest range consistent with the principles and novel features disclosed in the present application.

Claims

1. A relay drive control circuit, characterized in that: include: A control unit, an adjustable power supply unit, a negative pressure supply unit and a switch unit, wherein the control unit is electrically connected to the first ends of the adjustable power supply unit and the switch unit respectively, the negative pressure supply circuit is electrically connected to the second end of the adjustable power supply unit and is used to be electrically connected to an external relay unit, and the second end of the switch unit is used to be electrically connected to the relay unit; The adjustable power supply unit is used to: stop outputting the driving voltage to the relay unit when receiving the first shutdown control signal transmitted by the control unit; The negative pressure supply unit is used to: output a negative voltage to the relay unit when the adjustable power supply unit is in an off state; The control unit is used to: when the voltage of the relay coil in the relay unit decreases to a preset value, output a second shutdown control signal to the switch unit; The switch unit is used for: when receiving the second shutdown control signal, entering a cut-off state to control the relay unit to enter a shutdown state.

2. The relay drive control circuit according to claim 1, characterized in that: The negative pressure supply unit includes a voltage regulator tube, a capacitor unit and a first resistor; The cathode of the voltage regulator tube is electrically connected to one end of the first resistor and the first end of the capacitor unit, the anode of the voltage regulator tube is grounded, the other end of the first resistor is electrically connected to the second end of the adjustable power supply unit and is used to be electrically connected to the relay unit, the first end of the capacitor unit is also electrically connected to the switch unit, the second end of the capacitor unit is electrically connected to the second end of the adjustable power supply unit and is used to be electrically connected to the relay unit, and the third end of the capacitor unit is grounded.

3. The relay drive control circuit according to claim 2, characterized in that: The capacitor unit includes a first capacitor, a second capacitor and a third capacitor; One end of the first capacitor and the second capacitor are both electrically connected to the second end of the adjustable power supply unit, the other end of the first capacitor is grounded, the other end of the second capacitor is respectively electrically connected to one end of the third capacitor, the cathode of the voltage regulator tube and the switch unit, and the other end of the third capacitor is grounded.

4. The relay drive control circuit according to claim 1, characterized in that: The adjustable power supply unit includes an adjustable power supply chip, an enabling control unit and a feedback voltage regulating unit; The first end of the adjustable power chip is electrically connected to one end of the enable control unit, the second end of the adjustable power chip is electrically connected to the negative pressure supply unit and the first end of the feedback voltage regulation unit respectively, the third end of the adjustable power chip is electrically connected to the second end of the feedback voltage regulation unit, the other end of the enable control unit is electrically connected to the control unit, and the third end of the feedback voltage regulation unit is electrically connected to the control unit.

5. The relay drive control circuit according to claim 4, characterized in that: The feedback voltage regulating unit includes a second resistor, a third resistor and at least one resistance selection unit, one end of the second resistor is electrically connected to the second end of the adjustable power supply chip, the other end of the second resistor is electrically connected to one end of the third resistor, one end of the resistance selection unit and the third end of the adjustable power supply chip respectively, and the other ends of the third resistor and the resistance selection unit are both grounded.

6. The relay drive control circuit according to claim 5, characterized in that: The resistance selection unit includes a fourth resistor and a first switching device, one end of the fourth resistor is electrically connected to the other end of the second resistor, the other end of the fourth resistor is electrically connected to the first end of the first switching device, the second end of the first switching device is electrically connected to the control unit, and the third end of the first switching device is grounded.

7. The relay drive control circuit according to claim 4, characterized in that: The enabling control unit includes a fifth resistor, a sixth resistor and a second switching device, one end of the fifth resistor is electrically connected to the fourth end of the adjustable power supply chip, the other end of the fifth resistor is electrically connected to one end of the sixth resistor, the first end of the adjustable power supply chip, and the first end of the second switching device, respectively, the other end of the sixth resistor is grounded, the second end of the second switching device is electrically connected to the control unit, and the third end of the second switching device is grounded.

8. The relay drive control circuit according to claim 1, characterized in that: The switch unit includes at least one third switch device, a first end of the third switch device is used to be electrically connected to a corresponding relay in the relay unit, a second end of the third switch device is electrically connected to the control unit, and a third end of the third switch device is electrically connected to the negative pressure supply unit.

9. A relay drive control method, characterized in that: A relay drive control circuit as claimed in any one of claims 1 to 8, comprising: The adjustable power supply unit stops outputting the driving voltage to the relay unit when receiving the first shutdown control signal transmitted by the control unit; The negative pressure supply unit outputs a negative voltage to the relay unit when the adjustable power supply unit is in an off state; The control unit outputs a second shutoff control signal to the switch unit when the voltage of the relay coil in the relay unit decreases to a preset value; When receiving the second shutdown control signal, the switch unit enters a cut-off state to control the relay unit to enter a shutdown state.

10. A photovoltaic energy storage system, characterized in that: It comprises a relay unit and a relay drive control circuit as claimed in any one of claims 1 to 8.

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