Bidirectional outdoor power switching circuit

Abstract

The utility model discloses a bidirectional outdoor power switching circuit. The utility model discloses an EG 1615 chip, an EG 8026 chip, a first voltage conversion circuit module connected with the EG 1615 chip, a second voltage conversion circuit module connected with the EG 8026 chip and the first voltage conversion circuit module, a battery input port connected with the EG 1615 chip, an inversion output port connected with the EG 8026 chip, and a charging input port connected with the EG 8026 chip. According to the utility model, the EG1615 chip and the EG8026 chip are matched with the first voltage conversion circuit module and the second voltage conversion circuit module to convert the direct current voltage of the battery into the alternating current voltage, so that the alternating current can be used under the condition that no power grid exists outdoors. And meanwhile, alternating current voltage can be converted into direct current to charge the battery under the condition that an external direct current power supply is not used.

Description

Technical Field

[0001] The present disclosure relates to the technical field of voltage conversion circuits, and in particular to a bidirectional outdoor power conversion circuit. Background Art

[0002] Currently, when there is no power grid outdoors, the portable power supply cannot convert DC power into AC voltage, resulting in the inability to use AC power, and without using an external DC power supply, the AC voltage cannot be converted into DC power to power the battery. Utility Model Content

[0003] The present disclosure provides a bidirectional outdoor power conversion circuit to solve one of the technical problems recognized by the inventor.

[0004] The present disclosure provides a bidirectional outdoor power conversion circuit, including an EG1615 chip, wherein the EG1615 chip is used to control DC / DC conversion;

[0005] EG8026 chip, the EG8026 chip is used to control DC / AC inverter conversion and PFC boost;

[0006] A first voltage conversion circuit module connected to the EG1615 chip, the first voltage conversion circuit module is used to invert a DC low voltage into an AC high voltage, and then rectify the AC high voltage into a DC high voltage; or, convert a high DC voltage into a low DC voltage;

[0007] A second voltage conversion circuit module connected to the EG8026 chip and the first voltage conversion circuit module, the second voltage conversion circuit module is used to invert the DC high voltage into an AC 220V voltage, or convert the AC 220V voltage into a DC high voltage;

[0008] A battery input port connected to the EG1615 chip, wherein the battery input port is used to connect a battery;

[0009] An inverter output port connected to the EG8026 chip, the inverter output port being used to connect and output an inverted AC voltage;

[0010] A charging input port connected to the EG8026 chip, wherein the charging input port is used to access a power source.

[0011] Preferably, the first voltage conversion circuit module includes MOS tubes S1A, S1B, S2A, S2B, S3A, S3B, S4A, S4B, S5, S6, S7, S8 and a transformer T1, the gates of the MOS tubes S1A and S1B are connected to BSH02 of the EG1615 chip, the gates of the MOS tubes S2A and S2B are connected to BSL02 of the EG1615 chip, and the gates of the MOS tubes S3A and S3B are connected to the EG1615 chip. The gates of the MOS tubes S4A and S4B are connected to the BSL01 pin of the EG1615 chip, and the drains of the MOS tubes S1A, S1B, S2A, S2B, S3A, S3B, S4A, and S4B are connected to the battery input port; the first and second pins of the transformer T1 are respectively connected to the BSVS2 and BSVS1 pins of the EG1615 chip, and the third pin of the transformer T1 is respectively connected to the source of the MOS tube S5. The gate of the MOSFET S5 is connected to the DCH01 pin of the EG1615 chip, the gate of the MOSFET S6 is connected to the DCL01 pin of the EG1615 chip, the gate of the MOSFET S7 is connected to the DCH02 pin of the EG1615 chip, the gate of the MOSFET S8 is connected to the DCH03 pin of the EG1615 chip, and the gate of the MOSFET S8 is connected to the DCH04 pin of the EG1615 chip. 5 chip, the source of the MOSFET S5 is respectively connected to the DCSDH1 pin and the DCVS1 pin of the EG1615 chip, the source of the MOSFET S6 is connected to the DCIFB1P pin of the EG1615 chip, the source of the MOSFET S7 is respectively connected to the DCSDH2 pin and the DCVS2 pin of the EG1615 chip, and the source of the MOSFET S8 is connected to the DCIFB2P pin of the EG1615 chip.

[0012] Preferably, the second voltage conversion circuit module includes switch tubes S9, S10, S11, S12, inductors L2, L3, relays K2, K3, the drains of the switch tubes S9, S10, S11, S12 are connected to the drains of the MOS tubes S5, S6, S7, S8, the gate of the switch tube S9 is connected to the 2H0 pin of the EG8026 chip, the gate of the switch tube S10 is connected to the 2L0 pin of the EG8026 chip, the gate of the switch tube S11 is connected to the 1H0 pin of the EG8026 chip, the gate of the switch tube S12 is connected to the 1L0 pin of the EG8026 chip, the first pin of the inductor L2 is connected to the The switch tubes S9 and S10 are connected, the second pin of the inductor L2 is connected to the switch tubes S11 and S12 respectively, the third and third pins of the inductor L2 are connected to the first and second pins of the inductor L3 respectively, and the third and fourth pins of the inductor L3 are connected to the inverter output port; the relay K2 is arranged between the charging input port and the battery input port, one end of the relay K2 is connected to the CHGRLY2 pin of the EG8026 chip, one end of the relay K3 is connected to the charging input port, and the other end is arranged between the inductor L3 and the inverter output port, and the relay K3 is connected to the CHGRLY1 pin of the EG8026 chip.

[0013] Preferably, a high-voltage over-current detection circuit module is also included, and the high-voltage over-current detection circuit module includes a switch K1, diodes D23, D24, D25, and D26. The switch K1 is arranged between the third pin of the transformer T1 and the MOS tube S5, the diodes D23 and D24 are connected in series, the diodes D25 and D26 are connected in series, the diodes D23, D24 and the diodes D25 and D26 are connected in parallel, one end of the switch K1 is connected between the diodes D23 and D24, one end of the switch K1 is connected between the diodes D25 and D26, and one end of the diodes D23, D24, D25, and D26 is connected to the IFBHVN pin of the EG1615 chip.

[0014] Preferably, an AC current detection chip U9 is further included, and the IP+ and IP+ / 2 pins of the AC current detection chip U9 are connected to the relay K2, and the IP- and IP- / 2 pins of the AC current detection chip U9 are connected to the inverter output port.

[0015] Preferably, a zero-crossing detection circuit U6 is further included, one end of the zero-crossing detection circuit U6 is connected to the charging input port, and the other end is connected to the ACVIN and VZCIN pins of the EG8026 chip.

[0016] Preferably, a rectifier bridge D31 is further included, and the rectifier bridge D31 is arranged between the relay K2 and the battery input port.

[0017] The beneficial effects of the present disclosure are mainly as follows: the present invention converts the DC voltage of the battery into AC voltage through the EG1615 chip and the EG8026 chip, in combination with the first voltage conversion circuit module and the second voltage conversion circuit module, so that AC power can be used outdoors without a power grid. At the same time, the AC voltage can be converted into DC power to charge the battery without using an external DC power supply.

[0018] It should be understood that both the foregoing general description and the following specific embodiments are for the purpose of example and illustration and do not necessarily limit the present disclosure. The accompanying drawings, which are incorporated into and constitute a part of the specification, illustrate the subject matter of the present disclosure. At the same time, the specification and the drawings are used to explain the principles of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the specific embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 A block diagram of the circuit principle design of the embodiment of the present disclosure;

[0021] Figure 2 is a circuit schematic diagram of an embodiment of the present disclosure;

[0022] Figure 3 This is a partial enlarged schematic diagram of the EG1615 chip pins according to an embodiment of the present disclosure;

[0023] Figure 4 This is a partial enlarged schematic diagram of the EG8026 chip pins according to an embodiment of the present disclosure;

[0024] Figure 5 It is a partially enlarged schematic diagram of the first voltage conversion circuit module of the embodiment of the present disclosure;

[0025] Figure 6 It is a partially enlarged schematic diagram of the second voltage conversion circuit module of the embodiment of the present disclosure;

[0026] Figure 7 It is a partial enlarged schematic diagram of the zero-crossing detection circuit U6 of the embodiment of the present disclosure;

[0027] Icon: 1-EG1615 chip; 2-EG8026 chip; 3-first voltage conversion circuit module; 4-second voltage conversion circuit module; 5-battery input port; 6-inverter output port; 7-charging input port; 8-high voltage overcurrent detection circuit module. DETAILED DESCRIPTION

[0028] The technical solution of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all of the embodiments.

[0029] Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present disclosure.

[0030] In the description of the present disclosure, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present disclosure. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0031] In the description of the present disclosure, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.

[0032] Example

[0033] like Figure 1-7 As shown, this embodiment provides a bidirectional outdoor power conversion circuit, including an EG1615 chip 1, wherein the EG1615 chip 1 is used to control DC / DC conversion;

[0034] EG8026 chip 2, the EG8026 chip 2 is used to control DC / AC inverter conversion and PFC boost;

[0035] A first voltage conversion circuit module 3 connected to the EG1615 chip 1, the first voltage conversion circuit module 3 is used to invert a DC low voltage into an AC high voltage, and then rectify the AC high voltage into a DC high voltage; or, convert a high DC voltage into a low DC voltage;

[0036] A second voltage conversion circuit module 4 connected to the EG8026 chip 2 and the first voltage conversion circuit module 3, the second voltage conversion circuit module 4 is used to invert the DC high voltage into an AC 220V voltage, or convert the AC 220V voltage into a DC high voltage;

[0037] A battery input port 5 connected to the EG1615 chip 1, wherein the battery input port 5 is used to connect a battery;

[0038] An inverter output port 6 connected to the EG8026 chip 2, the inverter output port 6 being used to output an inverted AC voltage;

[0039] A charging input port 7 connected to the EG8026 chip 2, wherein the charging input port 7 is used to access a power source.

[0040] like Figure 1 As shown, Figure 1This is a circuit structure design block diagram of the utility model. The EG1615 chip 1 is responsible for controlling the DC / DC conversion part. It adopts an LC resonant dual active bridge (DAB) topology structure, which can realize bidirectional energy transmission. When used for inverter boost, it can convert the low-voltage DC voltage of the battery into a high-voltage DC voltage to provide the high voltage required for the subsequent DC / AC inverter; when used for charger buck, it can convert the high-voltage DC voltage of the mains after PFC boost into a low-voltage DC voltage to provide the constant voltage and constant current charging required for battery charging. Combined with the matching of LC resonant parameters and PWM operating frequency, the DC / DC stage can realize soft switching control of the switch tube. In the figure, EG8026 chip 2 is responsible for controlling the DC / AC inverter and PFC boost part. When used for DC / AC inverter, EG8026 chip 2 adopts the middle-aligned PWM modulation method with a modulation frequency of 20KHz. The advantage of this modulation method is that the frequency of the switch tube on the H bridge is 20KHz, and the switching frequency on the output inductor and output capacitor is twice the PWM frequency (40KHz). Compared with the unipolar or bipolar modulation method of the traditional inverter, under the same power, the switching loss on the MOS tube or IGBT tube is the same, and the frequency acting on the output inductor and capacitor is twice the traditional one. This modulation method can reduce the volume and wire diameter of the inductor; when used for PFC boost, EG8026 chip 2 adopts the traditional bridgeless PFC circuit structure, the two lower MOS tubes S10 and S12 of the active bridge are used for PWM modulation, and the two upper switch tubes S9 and S11 use the internal diode for synchronous freewheeling, the modulation frequency is 20KHz, and the average current control algorithm is used for control.

[0041] like Figure 3As shown, the first voltage conversion circuit module 3 includes MOS tubes S1A, S1B, S2A, S2B, S3A, S3B, S4A, S4B, S5, S6, S7, S8 and a transformer T1, the gates of the MOS tubes S1A and S1B are connected to BSH02 of the EG1615 chip 1, the gates of the MOS tubes S2A and S2B are connected to BSL02 of the EG1615 chip 1, and the gates of the MOS tubes S3A and S3B are connected to the EG1615 chip 1. The gates of the MOS tubes S4A and S4B are connected to the BSL01 pin of the EG1615 chip 1, and the drains of the MOS tubes S1A, S1B, S2A, S2B, S3A, S3B, S4A, and S4B are connected to the battery input port 5; the first and second pins of the transformer T1 are respectively connected to the BSVS2 and BSVS1 pins of the EG1615 chip 1, and the third pin of the transformer T1 is respectively connected to the source of the MOS tube S5. The fourth pin of the transformer T1 is connected to the source of the mos S7 and the drain of the mos S8, the gate of the mos S5 is connected to the DCH01 pin of the EG1615 chip 1, the gate of the mos S6 is connected to the DCL01 pin of the EG1615 chip 1, the gate of the mos S7 is connected to the DCH02 pin of the EG1615 chip 1, the gate of the mos S8 is connected to the DCH03 pin of the EG1615 chip 1, and the gate of the mos S8 is connected to the DCH04 pin of the EG1615 chip 1. The source of the MOSFET S5 is connected to the DCSDH1 pin and the DCVS1 pin of the EG1615 chip 1, the source of the MOSFET S6 is connected to the DCIFB1P pin of the EG1615 chip 1, the source of the MOSFET S7 is connected to the DCSDH2 pin and the DCVS2 pin of the EG1615 chip 1, and the source of the MOSFET S8 is connected to the DCIFB2P pin of the EG1615 chip 1.

[0042] When used as an inverter, MOS tubes S1A, S1B, S2A, S2B, S3A, S3B, S4A, S4B and transformer T1 invert the DC low voltage into AC high voltage, which is then rectified into DC high voltage by MOS tubes S5, S6, S7, S8.

[0043] When used as a charger to step down the voltage, MOS tubes S1A, S1B, S2A, S2B, S3A, S3B, S4A, S4B, S5, S6, S7, S8 and transformer T1 convert the high-voltage DC voltage of the AC power after PFC boosting into a low-voltage DC voltage to provide the constant-voltage and constant-current charging required for battery charging.

[0044] like Figure 4As shown, the second voltage conversion circuit module 4 includes switch tubes S9, S10, S11, S12, inductors L2, L3, relays K2, K3, the drains of the switch tubes S9, S10, S11, S12 are connected to the drains of the MOS tubes S5, S6, S7, S8, the gate of the switch tube S9 is connected to the 2H0 pin of the EG8026 chip 2, the gate of the switch tube S10 is connected to the 2L0 pin of the EG8026 chip 2, the gate of the switch tube S11 is connected to the 1H0 pin of the EG8026 chip 2, the gate of the switch tube S12 is connected to the 1L0 pin of the EG8026 chip 2, the first pin of the inductor L2 is connected to the switch tubes S9, S10, S11, S12, ... The switch tubes S9 and S10 are connected, the second pin of the inductor L2 is connected to the switch tubes S11 and S12 respectively, the third and third pins of the inductor L2 are connected to the first and second pins of the inductor L3 respectively, and the third and fourth pins of the inductor L3 are connected to the inverter output port 6; the relay K2 is arranged between the charging input port 7 and the battery input port 5, one end of the relay K2 is connected to the CHGRLY2 pin of the EG8026 chip 2, one end of the relay K3 is connected to the charging input port 7, and the other end is arranged between the inductor L3 and the inverter output port 6, and the relay K3 is connected to the CHGRLY1 pin of the EG8026 chip 2.

[0045] When used as an inverter, the switch tubes S9, S10, S11, S12 and the inductors L2, L3 invert the DC high voltage into an AC 220V voltage.

[0046] When used as a charger to step down the voltage, the switch tubes S9, S10, S11, S12, and the inductors L2 and L3 convert the AC 220V voltage into DC high voltage. Among them, the relays K2 and K3 are output conversion relays. When the charging input port 7 is connected to the 220V voltage, the inverter output port 6 directly outputs the AC power, stops the inverter work, and switches to the charging mode.

[0047] Furthermore, a high-voltage overcurrent detection circuit module 8 is also included, and the high-voltage overcurrent detection circuit module 8 includes a switch K1, a diode D23, D24, D25, and D26. The switch K1 is arranged between the third pin of the transformer T1 and the MOS tube S5, the diodes D23 and D24 are connected in series, the diodes D25 and D26 are connected in series, the diodes D23 and D24 and the diodes D25 and D26 are connected in parallel, one end of the switch K1 is connected between the diodes D23 and D24, one end of the switch K1 is connected between the diodes D25 and D26, and one end of the diodes D23, D24, D25, and D26 is connected to the IFBHVN pin of the EG1615 chip 1. The switch K1, the diodes D23, D24, D25, and D26 are for high-voltage overcurrent detection, and the output signal turns off the inversion when overcurrent occurs.

[0048] Furthermore, an AC current detection chip U9 is included, and the IP+ and IP+ / 2 pins of the AC current detection chip U9 are connected to the relay K2, and the IP- and IP- / 2 pins of the AC current detection chip U9 are connected to the inverter output port 6. The chip U9 detects AC current and outputs real-time power to the MCU to provide protection for overload.

[0049] Furthermore, a zero-crossing detection circuit U6 is also included, one end of which is connected to the charging input port 7, and the other end is connected to the ACVIN and VZCIN pins of the EG8026 chip 2. The zero-crossing detection circuit U6 inputs a zero-crossing detection, detects the mains phase and provides it to the MCU for synchronous rectification.

[0050] Furthermore, a rectifier bridge D31 is included, and the rectifier bridge D31 is arranged between the relay K2 and the battery input port 5. When the inverter board is not powered on, it provides power to the MCU.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A bidirectional outdoor power conversion circuit, characterized in that: include: EG1615 chip, the EG1615 chip is used to control DC / DC conversion; EG8026 chip, the EG8026 chip is used to control DC / AC inverter conversion and PFC boost; A first voltage conversion circuit module connected to the EG1615 chip, the first voltage conversion circuit module is used to invert a DC low voltage into an AC high voltage, and then rectify the AC high voltage into a DC high voltage; or, convert a high DC voltage into a low DC voltage; A second voltage conversion circuit module connected to the EG8026 chip and the first voltage conversion circuit module, the second voltage conversion circuit module is used to invert the DC high voltage into an AC 220V voltage, or convert the AC 220V voltage into a DC high voltage; A battery input port connected to the EG1615 chip, wherein the battery input port is used to connect a battery; An inverter output port connected to the EG8026 chip, the inverter output port being used to connect and output an inverted AC voltage; A charging input port connected to the EG8026 chip, wherein the charging input port is used to access a power source.

2. A bidirectional outdoor power conversion circuit according to claim 1, characterized in that: The first voltage conversion circuit module includes MOS tubes S1A, S1B, S2A, S2B, S3A, S3B, S4A, S4B, S5, S6, S7, S8 and a transformer T1, the gates of the MOS tubes S1A and S1B are connected to BSH02 of the EG1615 chip, the gates of the MOS tubes S2A and S2B are connected to BSL02 of the EG1615 chip, the gates of the MOS tubes S3A and S3B are connected to BS The gates of the MOS tubes S4A and S4B are connected to the BSL01 pin of the EG1615 chip, and the drains of the MOS tubes S1A, S1B, S2A, S2B, S3A, S3B, S4A, and S4B are connected to the battery input port; the first and second pins of the transformer T1 are respectively connected to the BSVS2 and BSVS1 pins of the EG1615 chip, and the third pin of the transformer T1 is respectively connected to the source and The drain of the mosifier S6 is connected, the fourth pin of the transformer T1 is respectively connected to the source of the mosifier S7 and the drain of the mosifier S8, the gate of the mosifier S5 is connected to the DCH01 pin of the EG1615 chip, the gate of the mosifier S6 is connected to the DCL01 pin of the EG1615 chip, the gate of the mosifier S7 is connected to the DCH02 pin of the EG1615 chip, the gate of the mosifier S8 is connected to the DCH03 pin of the EG1615 chip, and the gate of the mosifier S8 is connected to the DCH04 pin of the EG1615 chip. The source of the MOSFET S5 is connected to the DCSDH1 pin and the DCVS1 pin of the EG1615 chip respectively, the source of the MOSFET S6 is connected to the DCIFB1P pin of the EG1615 chip, the source of the MOSFET S7 is connected to the DCSDH2 pin and the DCVS2 pin of the EG1615 chip respectively, and the source of the MOSFET S8 is connected to the DCIFB2P pin of the EG1615 chip.

3. A bidirectional outdoor power conversion circuit according to claim 2, characterized in that: The second voltage conversion circuit module includes switch tubes S9, S10, S11, S12, inductors L2, L3, relays K2, K3, the drains of the switch tubes S9, S10, S11, S12 are connected to the drains of the MOS tubes S5, S6, S7, S8, the gate of the switch tube S9 is connected to the 2H0 pin of the EG8026 chip, the gate of the switch tube S10 is connected to the 2L0 pin of the EG8026 chip, the gate of the switch tube S11 is connected to the 1H0 pin of the EG8026 chip, the gate of the switch tube S12 is connected to the 1L0 pin of the EG8026 chip, the first pin of the inductor L2 is connected to the switch tubes S9, S10, S11, S12, ... The first and second pins of the inductor L2 are connected to the first and second pins of the inductor L3, respectively; the third and fourth pins of the inductor L3 are connected to the inverter output port; the relay K2 is arranged between the charging input port and the battery input port, one end of the relay K2 is connected to the CHGRLY2 pin of the EG8026 chip, one end of the relay K3 is connected to the charging input port, and the other end is arranged between the inductor L3 and the inverter output port, and the relay K3 is connected to the CHGRLY1 pin of the EG8026 chip.

4. A bidirectional outdoor power conversion circuit according to claim 2, characterized in that: It also includes a high-voltage over-current detection circuit module, which includes a switch K1, diodes D23, D24, D25, and D26. The switch K1 is arranged between the third pin of the transformer T1 and the MOS tube S5, the diodes D23 and D24 are connected in series, the diodes D25 and D26 are connected in series, the diodes D23 and D24 and the diodes D25 and D26 are connected in parallel, one end of the switch K1 is connected between the diodes D23 and D24, one end of the switch K1 is connected between the diodes D25 and D26, and one end of the diodes D23, D24, D25, and D26 is connected to the IFBHVN pin of the EG1615 chip.

5. A bidirectional outdoor power conversion circuit according to claim 3, characterized in that: It also includes an AC current detection chip U9, the IP+ and IP+ / 2 pins of the AC current detection chip U9 are connected to the relay K2, and the IP- and IP- / 2 pins of the AC current detection chip U9 are connected to the inverter output port.

6. A bidirectional outdoor power conversion circuit according to claim 3, characterized in that: It also includes a zero-crossing detection circuit U6, one end of which is connected to the charging input port, and the other end of which is connected to the ACVIN and VZCIN pins of the EG8026 chip.

7. A bidirectional outdoor power conversion circuit according to claim 3, characterized in that: A rectifier bridge D31 is also included, and the rectifier bridge D31 is arranged between the relay K2 and the battery input port.

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