High-reliability solid-state relay with pre-charging function

Abstract

The utility model discloses a high-reliability solid state relay with a pre-charging function, which relates to the technical field of contactless switching devices, and comprises an MCU (Microprogrammed Control Unit), a current detection circuit, a pre-charging control circuit and an output circuit, the output circuit comprises an MOS (Metal Oxide Semiconductor) tube Q1 and an MOS tube Q2; the current detection circuit is connected with the MCU and the output circuit and is used for detecting current flowing through the output circuit and generating a first current detection signal and a second current detection signal; the MCU is used for providing a reference signal for the pre-charging control circuit; based on a reference signal, a first current detection signal and a second current detection signal, the pre-charging control circuit is used for controlling an MOS tube Q1 to work in a variable resistance region and controlling an MOS tube Q2 to work in a saturation region when the solid-state relay executes a pre-charging function; or the MOS tube Q2 is controlled to work in the variable resistance region, and the MOS tube Q1 is controlled to work in the saturation region. According to the solid-state relay provided by the invention, the pre-charging function can be realized by utilizing the variable resistance characteristic of the MOSFET, and the solid-state relay has relatively high reliability.

Description

TECHNICAL FIELD

[0001] The utility model relates to a contactless switching device technical field especially a high reliability solid state relay with precharge function. BACKGROUND

[0002] Solid state relay (SSR) is a kind of contactless switch composed of microelectronic circuit, discrete electronic device and power electronic power device.It realizes the isolation of control end and load end through isolator, and uses small control signal to drive large current load.Solid state relay has multiple advantages, including no mechanical contact, no spark, no noise, strong anti-interference ability, small driving power, large surge current and strong power voltage adaptability.In addition, solid state relay also has the advantages of vibration resistance, impact resistance, noiselessness, fast response speed and high electromagnetic compatibility.

[0003] When forming power-on control circuit by using solid state relay, precharge relay and precharge resistor are usually arranged to form precharge loop to realize precharge function, and precharge loop cooperates with main relay and other elements to realize power-on control.But due to the large number of hardware devices involved in control, the circuit size and cost are greatly increased, and the whole power-on control process has high failure probability, so it is difficult to ensure the stability and reliability of power-on control process.

[0004] In addition, the solid state relay on the market can only be used for switching, and cannot judge the current size flowing through the relay.When the device in the subsequent circuit suddenly appears short circuit or other phenomena, resulting in instantaneous increase of input current exceeding the maximum design value, serious damage event will occur.The current solution to the phenomenon of current mutation is basically to protect through fuse (fuse).When the required current is too large, the volume of fuse used is also relatively large, which does not meet the design requirements.The existing solid state relay also lacks temperature control and monitoring, and cannot effectively protect against overtemperature, which affects the reliability of solid state relay. INVENTION CONTENTS

[0005] The present application provides a high reliability solid state relay with precharge function.

[0006] The technical scheme of the utility model is as follows:

[0007] A high reliability solid state relay with precharge function, comprising MCU, current detection circuit, precharge control circuit and output circuit, wherein,

[0008] The output circuit comprises a MOS tube Q1 and a MOS tube Q2, a drain of the MOS tube Q1 forms a first connection end of the output circuit, a source of the MOS tube Q1 is electrically connected with a source of the MOS tube Q2, a drain of the MOS tube Q2 forms a second connection end of the output circuit, and the output circuit is connected in series with the first connection end and the second connection end in a power supply loop of the load;

[0009] The current detection circuit is connected with the MCU and the output circuit, and is used for detecting a current flowing through the output circuit, generating a first current detection signal and a second current detection signal, and transmitting the first current detection signal and the second current detection signal to the pre-charge control circuit;

[0010] The MCU is used for providing a reference signal to the pre-charge control circuit, and based on the reference signal, the first current detection signal and the second current detection signal, the pre-charge control circuit is used for controlling the MOS tube Q1 to work in a variable resistance region and controlling the MOS tube Q2 to work in a saturation region, or controlling the MOS tube Q2 to work in the variable resistance region and controlling the MOS tube Q1 to work in the saturation region when the solid-state relay performs a pre-charge function.

[0011] Further, the current detection circuit comprises a variable resistor R137, resistors R38, R39, R118, R138, R139, R140, R142, R144, R145, R146, R147, R149, operational amplifiers U5A and U5B, an isolator U1 and an isolator U14, wherein,

[0012] A first end of the variable resistor R137 is connected with a source of the MOS tube Q1, and a second end of the variable resistor R137 is connected with a source of the MOS tube Q2.

[0013] The first end of the variable resistor R137 is connected with a non-inverting input end of the operational amplifier U5A through the resistor R139 and grounded through the resistor R39, and the second end of the variable resistor R137 is connected with an inverting input end of the operational amplifier U5A through the resistor R138 and grounded through the resistor R38.

[0014] Further, the first end of the variable resistor R137 is also connected with the inverting input end of the operational amplifier U5B through the resistor R144, and the second end of the variable resistor R137 is also connected with the non-inverting input end of the operational amplifier U5B through the resistor R145.

[0015] The output end of the operational amplifier U5A is connected with one end of the resistor R142 and one end of the resistor R149, the other end of the resistor R142 is connected with the inverting input end of the operational amplifier U5A, the other end of the resistor R149 is connected with the input end of the isolator U1 and the pre-charge control circuit, and the output end of the isolator U1 is connected with the MCU.

[0016] The output end of the operational amplifier U5B is connected with one end of the resistor R146 and one end of the resistor R118, the other end of the resistor R146 is connected with the inverting input end of the operational amplifier U5B, the other end of the resistor R118 is connected with the input end of the isolator U14 and the pre-charge control circuit, and the output end of the isolator U14 is connected with the MCU.

[0017] Further, the pre-charge control circuit comprises an optoelectronic coupler U18, an operational amplifier U2A, a resistor R4, a resistor R23, a resistor R24, a resistor R25, a resistor R26, a resistor R153, a capacitor C23 and a capacitor C11.

[0018] The anode of the primary light emitting diode of the optoelectronic coupler U18 is connected with the resistor R4, the cathode of the primary light emitting diode of the optoelectronic coupler U18 is grounded through the resistor R23, the collector of the secondary light sensitive triode of the optoelectronic coupler U18 is connected with the power supply voltage VSB1 and grounded through the capacitor C23, the emitter of the secondary light sensitive triode of the optoelectronic coupler U18 is grounded through the resistor R24, and is connected with one end of the capacitor C11, one end of the resistor R26 and the non-inverting input end of the operational amplifier U2A through the resistor R25, the other end of the capacitor C11 and the other end of the resistor R26 are grounded.

[0019] The inverting input end of the operational amplifier U2A is connected with the output end of the operational amplifier U5A through the resistor R149, and the output end of the operational amplifier U2A is connected with the gate of the MOS tube Q1 through the resistor R153 and the resistor R2.

[0020] Further, the pre-charge control circuit further comprises a resistor R5, a resistor R151, a resistor R152, a resistor R153, a resistor R187, a triode U13, a capacitor C8 and an optoelectronic coupler U3.

[0021] The inverting input end of the operational amplifier U2A is connected with the power supply voltage VSB1 through the resistor R151, and is connected with one end of the resistor R152 through the capacitor C8, the other end of the resistor R152 is connected with the output end of the operational amplifier U2A and one end of the resistor R5.

[0022] The other end of the resistor R5 is connected with the cathode of the original side light emitting diode of the photoelectric coupler U3, the anode of the original side light emitting diode of the photoelectric coupler U3 is connected with the base of the triode U13, the emitter of the triode U13 is connected with one end of the resistor R153 and one end of the resistor R187, the other end of the resistor R187 is grounded;

[0023] The collector of the triode U13 is connected with the negative power supply voltage VSB2, the emitter of the vice side photosensitive triode of the photoelectric coupler U3 is connected with the negative power supply voltage VSB2, and the collector of the vice side photosensitive triode of the photoelectric coupler U3 is connected with the driving circuit.

[0024] Further, the pre-charge control circuit further comprises an operational amplifier U2D, a resistor R8, a resistor R165, a resistor R166, a resistor R154, a resistor R188, a triode U12, a capacitor C10 and a photoelectric coupler U6, wherein,

[0025] The inverting input end of the operational amplifier U2D is connected with the output end of the operational amplifier U5B through the resistor R118, the noninverting input end of the operational amplifier U2D is connected with the emitter of the vice side photosensitive triode of the photoelectric coupler U18 through the resistor R25, and the output end of the operational amplifier U2D is connected with the gate of the MOS tube Q2 through the resistor R154 and the resistor R41;

[0026] The inverting input end of the operational amplifier U2D is connected with the power supply voltage VSB1 through the resistor R165, and connected with one end of the resistor R166 through the capacitor C10, the other end of the resistor R166 is connected with the output end of the operational amplifier U2D and one end of the resistor R8;

[0027] The other end of the resistor R8 is connected with the cathode of the original side light emitting diode of the photoelectric coupler U6, the anode of the original side light emitting diode of the photoelectric coupler U6 is connected with the base of the triode U12, the emitter of the triode U12 is connected with one end of the resistor R154 and one end of the resistor R188, the other end of the resistor R188 is grounded;

[0028] The collector of the triode U12 is connected with the negative power supply voltage VSB2, the emitter of the vice side photosensitive triode of the photoelectric coupler U6 is connected with the negative power supply voltage VSB2, and the collector of the vice side photosensitive triode of the photoelectric coupler U6 is connected with the driving circuit.

[0029] Further, the driving circuit comprises a photoelectric coupler U16, a driving chip U17, a resistor R16, a resistor R17, a resistor R27, a resistor R28, a resistor R206 and a resistor R207, wherein,

[0030] The MCU is connected with the anode of the primary side light emitting diode of the photoelectric coupler U16 through the resistor R16, the cathode of the primary side light emitting diode of the photoelectric coupler U16 is grounded, and the output end of the photoelectric coupler U16 is connected with the first input pin and the second input pin of the driving chip U17;

[0031] The first enable end of the driving chip U17 is connected with the collector of the secondary side photosensitive triode of the photoelectric coupler U3, the second enable end of the driving chip U17 is connected with the collector of the secondary side photosensitive triode of the photoelectric coupler U6, the first enable end is connected with one end of the resistor R27 through the resistor R28, and the other end of the resistor R27 is connected with the second enable end.

[0032] The first output end of the driving chip U17 is connected with the gate of the MOS tube Q1 through the resistor R206 and the resistor R2, and the second output end of the driving chip U17 is connected with the gate of the MOS tube Q2 through the resistor R207 and the resistor R41.

[0033] Further technical solutions are as follows: further comprising a voltage detection circuit, the voltage detection circuit comprises a capacitor C38, a capacitor C15, a capacitor C16, a capacitor C17, a capacitor C18, a capacitor C19, a capacitor C20, a capacitor C21, a photoelectric coupler U10, a photoelectric coupler U11, a resistor R15, a resistor R10, a resistor R12, a resistor R20, a resistor R6, a resistor R9, a resistor R7, a resistor R13, a diode D3, a diode D12, an operational amplifier U2B and an operational amplifier U2C, wherein,

[0034] The capacitor C38, the capacitor C15, the capacitor C18, the capacitor C16, the capacitor C19, the capacitor C21, the capacitor C20 and the capacitor C17 are connected in series between the first connection end and the second connection end of the output circuit, one end of the capacitor C18 and one end of the capacitor C16 are connected with the non-inverting input end of the operational amplifier U2B through the resistor R6, and the non-inverting input end of the operational amplifier U2B is further grounded through the resistor R9;

[0035] The inverting input end of the operational amplifier U2B is connected with the power supply voltage VSB1, the output end of the operational amplifier U2B is connected with the cathode of the diode D3 and one end of the resistor R15, the anode of the diode D3 and the other end of the resistor R15 are connected with the anode of the primary side light emitting diode of the photoelectric coupler U11, and the cathode of the primary side light emitting diode of the photoelectric coupler U11 is connected with the negative power supply voltage VBS2;

[0036] The collector of the secondary side photosensitive triode of the photoelectric coupler U11 is connected with the MCU and connected with the power supply voltage VCC through the resistor R20, and the emitter of the secondary side photosensitive triode of the photoelectric coupler U11 is grounded.

[0037] One end of the capacitor C19 and one end of the capacitor C21 are connected to the non-inverting input terminal of the operational amplifier U2C through the resistor R7, and the non-inverting input terminal of the operational amplifier U2C is also connected to the ground through the resistor R13;

[0038] The inverting input terminal of the operational amplifier U2C is connected to the power supply voltage VSB1, and the output terminal of the operational amplifier U2C is connected to the cathode of the diode D12 and one end of the resistor R10, and the anode of the diode D12 and the other end of the resistor R10 are connected to the anode of the primary light emitting diode of the optocoupler U10, and the cathode of the primary light emitting diode of the optocoupler U10 is connected to the negative power supply voltage VBS2.

[0039] The collector of the secondary light sensitive triode of the optocoupler U10 is connected to the MCU and connected to the power supply voltage VCC through the resistor R12, and the emitter of the secondary light sensitive triode of the optocoupler U10 is grounded.

[0040] Further technical solutions thereof are that the temperature detection circuit comprises a thermistor R31, an optocoupler U9, resistors R14, R18, R19, R22, R77, a capacitor C44 and a voltage comparator U8, wherein,

[0041] One end of the thermistor R31 is connected to the power supply voltage VSB1, and the other end of the thermistor R31 is connected to the non-inverting input terminal of the voltage comparator U8, and the non-inverting input terminal of the voltage comparator U8 is grounded through the resistor R77;

[0042] The inverting input terminal of the voltage comparator U8 is connected to the positive power supply terminal through the resistor R14, the positive power supply terminal of the voltage comparator U8 is connected to the power supply voltage VSB1, the negative power supply terminal of the voltage comparator U8 is grounded, the inverting input terminal of the voltage comparator U8 is also grounded through the resistor R18, one end of the capacitor C44 is connected to the positive power supply terminal of the voltage comparator U8, and the other end of the capacitor C44 is grounded.

[0043] The output terminal of the voltage comparator U8 is connected to the cathode of the primary light emitting diode of the optocoupler U9, the anode of the primary light emitting diode of the optocoupler U9 is connected to the power supply voltage VSB1 through the resistor R19, the collector of the secondary light sensitive triode of the optocoupler U9 is connected to the MCU and connected to the power supply voltage VCC through the resistor R22, and the emitter of the secondary light sensitive triode of the optocoupler U9 is grounded.

[0044] The beneficial technical effects of the utility model are:

[0045] When the pre-charging function is performed, the MOS tube Q1 or the MOS tube Q2 can be controlled by the pre-charging control circuit to work in the variable resistance region, the pre-charging function is realized by using the variable resistance characteristics of the MOSFET device working in the variable resistance region to replace the pre-charging circuit composed of the traditional pre-charging resistor and the pre-charging relay, and the number and cost of the used devices can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 is a circuit block diagram of one embodiment of the high-reliability solid-state relay with a pre-charging function provided by the utility model.

[0047] Figure 2 is a circuit principle diagram of the voltage detection circuit and the output circuit in one embodiment of the utility model.

[0048] Figure 3 is a circuit principle diagram of the pre-charging control circuit in one embodiment of the utility model.

[0049] Figure 4 is a circuit principle diagram of the driving circuit in one embodiment of the utility model.

[0050] Figure 5 is a circuit principle diagram of the voltage detection circuit in one embodiment of the utility model.

[0051] Figure 6 is a circuit principle diagram of the first optocoupler isolation circuit in one embodiment of the utility model.

[0052] Figure 7 is a circuit principle diagram of the second optocoupler isolation circuit in one embodiment of the utility model.

[0053] Figure 8 is a circuit principle diagram of the temperature detection circuit in one embodiment of the utility model.

[0054] Figure 9 is a signal timing diagram of various control signals in one embodiment of the utility model. DETAILED DESCRIPTION

[0055] The specific embodiments of the utility model will be further described in combination with the drawings.

[0056] The utility model provides a kind of high-reliability solid-state relay with pre-charging function, as shown in figure Figure 1 It includes MCU, current detection circuit, pre-charging control circuit and output circuit, wherein,

[0057] The output circuit comprises a MOS tube Q1 and a MOS tube Q2, a drain of the MOS tube Q1 forms a first connecting end of the output circuit, a source of the MOS tube Q1 is electrically connected with a source of the MOS tube Q2, a drain of the MOS tube Q2 forms a second connecting end of the output circuit, and the output circuit is connected in series between the first connecting end and the second connecting end in a power supply loop of the load;

[0058] The current detection circuit is connected with the MCU and the output circuit, and is used for detecting a current flowing through the output circuit, generating a first current detection signal and a second current detection signal, and transmitting the first current detection signal and the second current detection signal to the pre-charge control circuit;

[0059] The MCU is used for providing a reference signal to the pre-charge control circuit, and based on the reference signal, the first current detection signal and the second current detection signal, the pre-charge control circuit is used for controlling the MOS tube Q1 to work in a variable resistance region and controlling the MOS tube Q2 to work in a saturation region, or controlling the MOS tube Q2 to work in the variable resistance region and controlling the MOS tube Q1 to work in the saturation region when the solid-state relay performs a pre-charge function.

[0060] Specifically, the power-on control circuit formed by the solid-state relay comprises a pre-charge working state and a normal working state in sequence, the pre-charge working state is that the load is pre-charged by performing the pre-charge function of the solid-state relay before the normal working state, and a voltage mutation at a normal power supply instant causes damage to the load. Based on the variable resistance characteristic of the MOSFET tube working in the variable resistance region, the pre-charge control circuit is used for controlling the MOS tube Q1 or the MOS tube Q2 to work in the variable resistance region, the pre-charge circuit composed of the traditional pre-charge resistor and the pre-charge relay is replaced by the MOSFET device working in the variable resistance region, the pre-charge function is realized, and the number and cost of devices used can be reduced. The variable resistance characteristic of the MOSFET tube specifically refers to that when the MOSFET tube works in the variable resistance region, the drain current ID has a linear relationship with the drain-source voltage Vds under the condition that the gate-source voltage Vgs is constant, and the MOSFET tube can be equivalent to a resistance for use.

[0061] The output circuit is a non-polarity circuit, that is, the output circuit can be connected in series in the power supply loop without distinguishing the positive and negative polarities, in the embodiment, the MOS tube Q1 and the MOS tube Q2 are both NMOS tubes, as shown in the figure, when the current flows from the first connecting end (hereinafter referred to as HVL-D) to the second connecting end (hereinafter referred to as HVR-D) of the output circuit, the MOS tube Q1 works in the variable resistance region and the MOS tube Q2 works in the saturation region, and when the current flows from HVR-D to HVL-D, the MOS tube Q2 works in the variable resistance region and the MOS tube Q1 works in the saturation region. Figure 2

[0062] ​Further, the current detection circuit comprises a rheostat R137, a resistor R38, a resistor R39, a resistor R118, a resistor R138, a resistor R139, a resistor R140, a resistor R142, a resistor R144, a resistor R145, a resistor R146, a resistor R147, a resistor R149, an operational amplifier U5A, an operational amplifier U5B, an isolator U1 and an isolator U2, wherein,

[0063] A first end of the rheostat R137 is connected with a source of the MOS tube Q1, and a second end of the rheostat R137 is connected with a source of the MOS tube Q2; the first end of the rheostat R137 is connected with a non-inverting input terminal of the operational amplifier U5A through the resistor R139, and is grounded through the resistor R39; the second end of the rheostat R137 is connected with an inverting input terminal of the operational amplifier U5A through the resistor R138, and is grounded through the resistor R38. The first end of the rheostat R137 is also connected with the inverting input terminal of the operational amplifier U5B through the resistor R144, and the second end of the rheostat R137 is also connected with the non-inverting input terminal of the operational amplifier U5B through the resistor R145;

[0064] An output terminal of the operational amplifier U5A is connected with one end of the resistor R142 and one end of the resistor R149, another end of the resistor R142 is connected with the inverting input terminal of the operational amplifier U5A, another end of the resistor R149 is connected with an input terminal of the isolator U1 and a pre-charge control circuit, and an output terminal of the isolator U1 is connected with the MCU;

[0065] An output terminal of the operational amplifier U5B is connected with one end of the resistor R146 and one end of the resistor R118, another end of the resistor R146 is connected with the inverting input terminal of the operational amplifier U5B, another end of the resistor R118 is connected with an input terminal of the isolator U14 and the pre-charge control circuit, and an output terminal of the isolator U14 is connected with the MCU.

[0066] Specifically, the variable resistor R137 serves as a sampling resistor to detect the current flowing through the output circuit, generating a first sampling voltage HVL-S and a second sampling voltage HVR-S. When the current flows from HVL-D to HVR-D, the second sampling voltage HVR-S is zero; when the current flows from HVR-D to HVL-D, the first sampling voltage HVL-S is zero. The first sampling voltage HVL-S and the second sampling voltage HVR-S are input to operational amplifiers U5A and U5B, and after differential amplification, they correspondingly generate a first current detection signal (hereinafter referred to as the IAMPAL signal) and a second current detection signal (hereinafter referred to as the IAMPAR signal). It should be noted that in this embodiment, operational amplifiers U5A and U5B are integrated into the dual operational amplifier chip U5. While the IAMPAL and IAMPAR signals are output to the precharge control circuit, they are also input to isolators U1 and U14 respectively. Isolator U1 outputs the ISENSEL signal based on the IAMPAL signal, and isolator U14 outputs the ISENSEL signal based on the IAMPAR signal. The MCU monitors the magnitude of the power supply circuit current by monitoring the ISENSEL and ISENSEL signals to perform overcurrent protection when the current is too high. The specific method of the overcurrent protection can be referred to the following description.

[0067] Furthermore, the pre-charge control circuit includes an optocoupler U18, an operational amplifier U2A, resistors R4, R23, R24, R25, R26, R153, capacitor C23, and capacitor C11, wherein...

[0068] like Figure 3 As shown, the MCU is connected to the anode of the primary-side LED of optocoupler U18 via resistor R4. The cathode of the primary-side LED of optocoupler U18 is grounded via resistor R23. The collector of the secondary-side phototransistor of optocoupler U18 is connected to the power supply voltage VSB1 and grounded via capacitor C23. The emitter of the secondary-side phototransistor of optocoupler U18 is grounded via resistor R24 ​​and connected to one end of capacitor C11, one end of resistor R26, and the non-inverting input terminal of operational amplifier U2A via resistor R25. The other end of capacitor C11 and the other end of resistor R26 are grounded.

[0069] The inverting input terminal of the operational amplifier U2A is connected to the output terminal of the operational amplifier U5A through resistor R149, and the output terminal of the operational amplifier U2A is connected to the gate of the MOS transistor Q1 through resistors R153 and R2.

[0070] The pre-charge control circuit also includes resistors R5, R151, R152, R153, and R187, transistor U13, capacitor C8, and optocoupler U3, wherein...

[0071] The inverting input terminal of the operational amplifier U2A is connected to the power supply voltage VSB1 through the resistor R151, and is connected to the output terminal of the operational amplifier U2A and one end of the resistor R5 through the capacitor C8 and the other end of the resistor R152;

[0072] The other end of the resistor R5 is connected to the cathode of the primary light emitting diode of the opto-coupler U3, the anode of the primary light emitting diode of the opto-coupler U3 is connected to the base of the triode U13, the emitter of the triode U13 is connected to one end of the resistor R153 and one end of the resistor R187, and the other end of the resistor R187 is grounded;

[0073] The collector of the triode U13 is connected to the negative power supply voltage VSB2, the emitter of the secondary light sensitive triode of the opto-coupler U3 is connected to the negative power supply voltage VSB2, and the collector of the secondary light sensitive triode of the opto-coupler U3 is connected to the driving circuit.

[0074] The pre-charge control circuit further comprises an operational amplifier U2D, a resistor R8, a resistor R165, a resistor R166, a resistor R154, a resistor R188, a triode U12, a capacitor C10, and an opto-coupler U6, wherein,

[0075] The inverting input terminal of the operational amplifier U2D is connected to the output terminal of the operational amplifier U5B through the resistor R118, the non-inverting input terminal of the operational amplifier U2D is connected to the emitter of the secondary light sensitive triode of the opto-coupler U18 through the resistor R25, and the output terminal of the operational amplifier U2D is connected to the gate of the MOS tube Q2 through the resistor R154 and the resistor R41;

[0076] The inverting input terminal of the operational amplifier U2D is connected to the power supply voltage VSB1 through the resistor R165, and is connected to the output terminal of the operational amplifier U2D and one end of the resistor R8 through the capacitor C10 and the other end of the resistor R166;

[0077] The other end of the resistor R8 is connected to the cathode of the primary light emitting diode of the opto-coupler U6, the anode of the primary light emitting diode of the opto-coupler U6 is connected to the base of the triode U12, the emitter of the triode U12 is connected to one end of the resistor R154 and one end of the resistor R188, and the other end of the resistor R188 is grounded;

[0078] The collector of the triode U12 is connected to the negative power supply voltage VSB2, the emitter of the secondary light sensitive triode of the opto-coupler U6 is connected to the negative power supply voltage VSB2, and the collector of the secondary light sensitive triode of the opto-coupler U6 is connected to the driving circuit.

[0079] Specifically, the IAMPAL signal is input to the inverting input terminal of the operational amplifier U2A, and the IAMPAR signal is input to the inverting input terminal of the operational amplifier U2D. The MCU outputs the DRV_ILIMIT signal to the optocoupler U18, and the DRV_ILIMIT signal is divided by the resistor R25 and the resistor R26 after passing through the optocoupler U18 to obtain the reference signal, that is, the ICOMS signal. Because the resistor R25 and the capacitor C11 constitute an RC delay circuit, the ICOMS signal output to the operational amplifier U2A and the operational amplifier U2D slowly increases to be stable. The operational amplifier U2A compares the IAMPAL signal and the ICOMS signal, and outputs the GATE_L signal to control the gate voltage of the MOS tube Q1; the operational amplifier U2D compares the IAMPAR signal and the ICOMS signal, and outputs the GATE_R signal to control the gate voltage of the MOS tube Q1. When the ICOMS signal is greater than the IAMPAL signal / IAMPAR signal, the operational amplifier U2A / U2D outputs the high-level GATE_L signal / GATE_R signal; when the ICOMS signal is less than the IAMPAL signal / IAMPAR signal, the operational amplifier U2A / U2D outputs the low-level GATE_L signal / GATE_R signal, so as to control the working state of the MOS tube Q1 and the MOS tube Q2 by controlling the gate voltage of the MOS tube Q1 and the MOS tube Q2. In the embodiment, the power supply voltage VSB1 is 5V, and the negative power supply voltage VSB2 is -3V.

[0080] Further, the solid-state relay further comprises a driving circuit, such as Figure 4 As shown, the driving circuit comprises the optocoupler U16, the driving chip U17, the resistor R16, the resistor R17, the resistor R27, the resistor R28, the resistor R206, and the resistor R207, wherein,

[0081] The MCU is connected with the anode of the primary light-emitting diode of the optocoupler U16 through the resistor R16, the cathode of the primary light-emitting diode of the optocoupler U16 is grounded, and the output terminal of the optocoupler U16 is connected with the first input pin and the second input pin of the driving chip U17;

[0082] The first enable terminal of the driving chip U17 is connected with the collector of the secondary photosensitive triode of the optocoupler U3, the second enable terminal of the driving chip U17 is connected with the collector of the secondary photosensitive triode of the optocoupler U6, the first enable terminal is connected with one end of the resistor R27 through the resistor R28, and the other end of the resistor R27 is connected with the second enable terminal;

[0083] The first output end of the drive chip U17 is connected with the gate of the MOS tube Q1 through the resistance R206 and the resistance R2, and the second output end of the drive chip U17 is connected with the gate of the MOS tube Q2 through the resistance R207 and the resistance R41.

[0084] Specifically, the optoelectronic coupler U16 is a high-speed optoelectronic coupler, and the output side of the optoelectronic coupler U16 includes a power supply end, an output end and a ground end, the power supply end is connected with the output end through the capacitor C40 and the capacitor C41, and the functions of the power supply end, the output end and the ground end are the same as those of the existing high-speed optoelectronic coupler. The drive circuit is used to drive the MOS tube Q1 and the MOS tube Q2 when the power-on control circuit works in the normal working state after the pre-charging is completed. When the power-on control circuit works in the normal working state, the MCU outputs a high-level DRVON signal, the DRVON signal is fed back to the input end of the drive chip U17 through the optoelectronic coupler U16, and the drive chip U17 controls the gate voltage of the MOS tube Q1 and the MOS tube Q2 to make the MOS tube Q1 and the MOS tube Q2 completely conductive.

[0085] In order to avoid that the drive chip U17 drives the MOS tube Q1 and the MOS tube Q2 when performing the pre-charging function, the optoelectronic coupler U3 in the pre-charging control circuit outputs a GATELEN signal to the first enable end of the drive chip U17, and the optoelectronic coupler U6 in the pre-charging control circuit outputs a GATEREN signal to the second enable end of the drive chip U17. When the GATE_L signal output by the operational amplifier U2A is high level, the triode U13 is turned on to make the primary side light emitting diode of the optoelectronic coupler U3 conductive, the optoelectronic coupler U3 outputs a low-level GATELEN signal to make the first output end of the drive chip U17 close. Similarly, when the GATE_R signal output by the operational amplifier U2D is high level, the triode U12 is turned on to make the primary side light emitting diode of the optoelectronic coupler U6 conductive, the optoelectronic coupler U6 outputs a low-level GATEREN signal to make the second output end of the drive chip U17 close.

[0086] Further, the solid-state relay further includes a voltage detection circuit, the voltage detection circuit includes the capacitor C38, the capacitor C15, the capacitor C16, the capacitor C17, the capacitor C18, the capacitor C19, the capacitor C20, the capacitor C21, the optoelectronic coupler U10, the optoelectronic coupler U11, the resistance R15, the resistance R10, the resistance R12, the resistance R20, the resistance R6, the resistance R9, the resistance R7, the resistance R13, the diode D3, the diode D12, the operational amplifier U2B and the operational amplifier U2C, wherein,

[0087] The capacitor C38, the capacitor C15, the capacitor C18, the capacitor C16, the capacitor C19, the capacitor C21, the capacitor C20 and the capacitor C17 are connected in series between the first connection end and the second connection end of the output circuit, one end of the capacitor C18 and one end of the capacitor C16 are connected to the non-inverting input terminal of the operational amplifier U2B through the resistor R6, and the non-inverting input terminal of the operational amplifier U2B is also connected to the ground through the resistor R9;

[0088] The inverting input terminal of the operational amplifier U2B is connected to the power supply voltage VSB1, the output terminal of the operational amplifier U2B is connected to the cathode of the diode D3 and one end of the resistor R15, the anode of the diode D3 and the other end of the resistor R15 are connected to the anode of the primary light emitting diode of the optocoupler U11, and the cathode of the primary light emitting diode of the optocoupler U11 is connected to the negative power supply voltage VBS2.

[0089] The collector of the secondary light sensitive triode of the optocoupler U11 is connected to the MCU and connected to the power supply voltage VCC through the resistor R20, and the emitter of the secondary light sensitive triode of the optocoupler U11 is connected to the ground.

[0090] One end of the capacitor C19 and one end of the capacitor C21 are connected to the non-inverting input terminal of the operational amplifier U2C through the resistor R7, and the non-inverting input terminal of the operational amplifier U2C is also connected to the ground through the resistor R13.

[0091] The inverting input terminal of the operational amplifier U2C is connected to the power supply voltage VSB1, the output terminal of the operational amplifier U2C is connected to the cathode of the diode D12 and one end of the resistor R10, the anode of the diode D12 and the other end of the resistor R10 are connected to the anode of the primary light emitting diode of the optocoupler U10, and the cathode of the primary light emitting diode of the optocoupler U10 is connected to the negative power supply voltage VBS2.

[0092] The collector of the secondary light sensitive triode of the optocoupler U10 is connected to the MCU and connected to the power supply voltage VCC through the resistor R12, and the emitter of the secondary light sensitive triode of the optocoupler U10 is connected to the ground.

[0093] Specifically, the voltage detection circuit is used to detect the voltage HV between HVR-D and HVL-D. Capacitors C38, C15, C18, C16, C19, C21, C20, and C17 constitute a voltage divider sampling circuit. Optocoupler U10, resistors R10 and R12, and diode D12 constitute a first optocoupler isolation circuit. Optocoupler U11, resistors R15 and R20, and diode D3 constitute a second optocoupler isolation circuit. One end of capacitor C18 is connected to one end of capacitor C16 to form a first sampling terminal, which inputs VSL voltage to operational amplifier U2B. The voltage signal is input to the operational amplifier U2B by connecting one end of capacitor C19 and one end of capacitor C21 to form a second sampling terminal. The VSR voltage signal is divided and compared with VSB1. When the VSL voltage signal / VSR voltage signal is less than VSB1, the operational amplifier U2B / Operational amplifier U2C outputs a high-level VSL_O signal / VSR_O signal, which lights up the primary-side LED of optocoupler U10 / Operational coupler U11, outputting a high-level VDIFFSENSEL signal / VDIFFSENSER signal to the MCU. In this embodiment, by setting the resistance values ​​of resistors R6, R9, R7, and R13 and the value of VSB1, the VDIFFSENSEL signal / VDIFFSENSER signal is a high-level signal when HV is less than 10V. It should be noted that in this embodiment, operational amplifiers U2A, U2B, U2C, and U2D are integrated into a quad operational amplifier chip U2. In this embodiment, the power supply voltage VCC is 3.3V.

[0094] In this embodiment, the MCU can control the power-on control circuit to automatically switch from the pre-charge working state to the normal working state according to the value of HV. Taking the current flowing from HVL-D to HVR-D as an example, when performing the pre-charge function, MOSFET Q1 operates in the variable resistance region. Figure 9 As shown in the signal timing diagram, as the ICOMMS signal gradually increases, the GATE_L signal increases, the IAMPAL signal increases, and the voltage HV between HVR-D and HVL-D decreases accordingly. When HV is less than 10V, the VDIFFSENSER signal is a high-level signal, and the MCU outputs a high-level DRVON signal. The DRVON signal is fed back to the driver chip U17 through the optocoupler U16. The driver chip U17 drives both MOS transistors Q1 and Q2 to be fully turned on, that is, both are working in the saturation region.

[0095] Further, the solid state relay further comprises a temperature detection circuit, the temperature detection circuit comprising a thermistor R31, a photoelectric coupler U9, a resistor R14, a resistor R18, a resistor R19, a resistor R22, a resistor R77, a capacitor C44 and a voltage comparator U8, wherein,

[0096] One end of the thermistor R31 is connected to a power supply voltage VSB1, and the other end of the thermistor R31 is connected to a non-inverting input terminal of the voltage comparator U8, and the non-inverting input terminal of the voltage comparator U8 is grounded through the resistor R77;

[0097] The inverting input terminal of the voltage comparator U8 is connected to a positive power supply terminal through the resistor R14, the positive power supply terminal of the voltage comparator U8 is connected to the power supply voltage VSB1, and the negative power supply terminal of the voltage comparator U8 is grounded, the inverting input terminal of the voltage comparator U8 is also grounded through the resistor R18, one end of the capacitor C44 is connected to the positive power supply terminal of the voltage comparator U8, and the other end of the capacitor C44 is grounded;

[0098] The output terminal of the voltage comparator U8 is connected to the cathode of the primary light emitting diode of the photoelectric coupler U9, the anode of the primary light emitting diode of the photoelectric coupler U9 is connected to the power supply voltage VSB1 through the resistor R19, the collector of the secondary light sensitive triode of the photoelectric coupler U9 is connected to the MCU and connected to the power supply voltage VCC through the resistor R22, and the emitter of the secondary light sensitive triode of the photoelectric coupler U9 is grounded.

[0099] In order to improve the reliability of the solid state relay, the solid state relay further has an overcurrent and overtemperature protection function, and the specific implementation form of the overcurrent protection is that when the MCU detects that the ISENSEL signal / ISENSER signal is greater than an overcurrent threshold, the DRVON signal and the DRV_ILIMT signal are low, so as to control the MOS tube Q1 and the MOS tube Q2 to be turned off, so as to realize overcurrent protection.

[0100] The specific implementation form of the over-temperature protection is that the thermistor R31 is arranged near the output circuit and near the MOS tube Q1 and the MOS tube Q2, the resistance value of the thermistor R31 decreases with the increase of temperature, the temperature sampling signal TSENSE generated by the thermistor R31 is loaded to the positive input end of the voltage comparator U8, and the voltage signal loaded to the inverse input end of the voltage comparator U8 is compared, in the embodiment, the inverse input end voltage is the reference voltage obtained by dividing the 5V power voltage VSB1 through the resistor R14 and the resistor R18, and the reference voltage can be adjusted by adjusting the resistance value ratio of the resistor R14 and the resistor R18. The temperature sampling signal TSENSE decreases with the increase of the temperature of the output circuit, when the temperature of the output circuit is too high, the temperature sampling signal TSENSE is less than the reference voltage, the voltage comparator U8 outputs the low-level voltage to make the primary light emitting diode of the photoelectric coupler U9 conduct, so that the secondary light-sensitive triode of the photoelectric coupler U9 is turned on, and the MCU detects the low-level temperature detection signal OTP. When the MCU detects the low-level temperature detection signal OTP, the DRVON signal and the DRV_ILIMT signal are low level, so as to control the MOS tube Q1 and the MOS tube Q2 to be turned off, so as to realize the over-temperature protection.

[0101] The above only describes the preferred embodiments of the present application, and the present application is not limited to the above embodiments. It can be understood that other improvements and changes directly derived or thought by those skilled in the art without departing from the spirit and concept of the present application should be considered to be included in the protection scope of the present application.

Claims

1. A high reliability solid state relay with pre-charge function, characterized by, The solid-state relay comprises an MCU, a current detection circuit, a pre-charge control circuit and an output circuit, wherein, The output circuit comprises a MOS tube Q1 and a MOS tube Q2, a drain of the MOS tube Q1 forms a first connection end of the output circuit, a source of the MOS tube Q1 is electrically connected with a source of the MOS tube Q2, a drain of the MOS tube Q2 forms a second connection end of the output circuit, and the output circuit is connected in series with the first connection end and the second connection end in a power supply loop of a load; The current detection circuit is connected with the MCU and the output circuit, and is used for detecting a current flowing through the output circuit, generating a first current detection signal and a second current detection signal and transmitting the first current detection signal and the second current detection signal to the pre-charge control circuit; The MCU is used for providing a reference signal to the pre-charge control circuit, and based on the reference signal, the first current detection signal and the second current detection signal, the pre-charge control circuit is used for controlling the MOS tube Q1 to work in a variable resistance region and controlling the MOS tube Q2 to work in a saturation region, or controlling the MOS tube Q2 to work in the variable resistance region and controlling the MOS tube Q1 to work in the saturation region when the solid-state relay performs a pre-charge function.

2. The high reliability solid state relay with pre-charge function according to claim 1, characterized in that, The current detection circuit comprises a variable resistor R137, resistors R38, R39, R118, R138, R139, R140, R142, R144, R145, R146, R147, R149, operational amplifiers U5A, U5B, an isolator U1 and an isolator U14, wherein, A first end of the variable resistor R137 is connected with a source of the MOS tube Q1, and a second end of the variable resistor R137 is connected with a source of the MOS tube Q2; The first end of the variable resistor R137 is connected with a non-inverting input end of the operational amplifier U5A through the resistor R139 and grounded through the resistor R39, and the second end of the variable resistor R137 is connected with an inverting input end of the operational amplifier U5A through the resistor R138 and grounded through the resistor R38.

3. The high reliability solid state relay with pre-charge function according to claim 2, characterized in that, The first end of the variable resistor R137 is further connected with the inverting input end of the operational amplifier U5B through the resistor R144, and the second end of the variable resistor R137 is further connected with the non-inverting input end of the operational amplifier U5B through the resistor R145; An output end of the operational amplifier U5A is connected with one end of a resistor R142 and one end of a resistor R149, the other end of the resistor R142 is connected with the inverting input end of the operational amplifier U5A, the other end of the resistor R149 is connected with an input end of the isolator U1 and the pre-charge control circuit, and an output end of the isolator U1 is connected with the MCU; An output end of the operational amplifier U5B is connected with one end of a resistor R146 and one end of a resistor R118, the other end of the resistor R146 is connected with the inverting input end of the operational amplifier U5B, the other end of the resistor R118 is connected with an input end of the isolator U14 and the pre-charge control circuit, and an output end of the isolator U14 is connected with the MCU.

4. The high reliability solid state relay with pre-charge function according to claim 3, characterized in that, The pre-charge control circuit comprises a photoelectric coupler U18, an operational amplifier U2A, a resistor R4, a resistor R23, a resistor R24, a resistor R25, a resistor R26, a resistor R153, a capacitor C23 and a capacitor C11, wherein, The MCU is connected with the anode of the primary light emitting diode of the photoelectric coupler U18 through the resistor R4, the cathode of the primary light emitting diode of the photoelectric coupler U18 is grounded through the resistor R23, the collector of the secondary light sensitive triode of the photoelectric coupler U18 is connected with the power supply voltage VSB1 and grounded through the capacitor C23; the emitter of the secondary light sensitive triode of the photoelectric coupler U18 is grounded through the resistor R24, and is connected with one end of the capacitor C11, one end of the resistor R26 and the non-inverting input terminal of the operational amplifier U2A through the resistor R25, the other end of the capacitor C11 and the other end of the resistor R26 are grounded; The inverting input terminal of the operational amplifier U2A is connected with the output terminal of the operational amplifier U5A through the resistor R149, and the output terminal of the operational amplifier U2A is connected with the gate of the MOS tube Q1 through the resistor R153 and the resistor R2.

5. The high reliability solid state relay with pre-charge function according to claim 4, characterized in that, The pre-charge control circuit further comprises a resistor R5, a resistor R151, a resistor R152, a resistor R153, a resistor R187, a triode U13, a capacitor C8 and a photoelectric coupler U3, wherein, The inverting input terminal of the operational amplifier U2A is connected with the power supply voltage VSB1 through the resistor R151, and is connected with one end of the resistor R152 through the capacitor C8, the other end of the resistor R152 is connected with the output terminal of the operational amplifier U2A and one end of the resistor R5; The other end of the resistor R5 is connected with the cathode of the primary light emitting diode of the photoelectric coupler U3, the anode of the primary light emitting diode of the photoelectric coupler U3 is connected with the base of the triode U13, the emitter of the triode U13 is connected with one end of the resistor R153 and one end of the resistor R187, the other end of the resistor R187 is grounded; The collector of the triode U13 is connected with the negative power supply voltage VSB2, the emitter of the secondary light sensitive triode of the photoelectric coupler U3 is connected with the negative power supply voltage VSB2, and the collector of the secondary light sensitive triode of the photoelectric coupler U3 is connected with the driving circuit.

6. The high reliability solid state relay with pre-charge function according to claim 5, characterized in that, The pre-charge control circuit further comprises an operational amplifier U2D, a resistor R8, a resistor R165, a resistor R166, a resistor R154, a resistor R188, a triode U12, a capacitor C10 and a photoelectric coupler U6, wherein, The inverting input terminal of the operational amplifier U2D is connected with the output terminal of the operational amplifier U5B through the resistor R118, the non-inverting input terminal of the operational amplifier U2D is connected with the emitter of the secondary light sensitive triode of the photoelectric coupler U18 through the resistor R25, and the output terminal of the operational amplifier U2D is connected with the gate of the MOS tube Q2 through the resistor R154 and the resistor R41; The inverting input terminal of the operational amplifier U2D is connected to the power supply voltage VSB1 through the resistor R165, and is connected to the resistor R166 through the capacitor C10, one end of the resistor R166 is connected to the output terminal of the operational amplifier U2D and one end of the resistor R8; The other end of the resistor R8 is connected to the cathode of the primary light emitting diode of the photoelectric coupler U6, the anode of the primary light emitting diode of the photoelectric coupler U6 is connected to the base of the triode U12, the emitter of the triode U12 is connected to one end of the resistor R154 and one end of the resistor R188, the other end of the resistor R188 is grounded; The collector of the triode U12 is connected to the negative power supply voltage VSB2, the emitter of the secondary light sensitive triode of the photoelectric coupler U6 is connected to the negative power supply voltage VSB2, and the collector of the secondary light sensitive triode of the photoelectric coupler U6 is connected to the driving circuit.

7. The high reliability solid state relay with pre-charge function according to claim 6, characterized in that, The driving circuit includes the photoelectric coupler U16, the driving chip U17, the resistor R16, the resistor R17, the resistor R27, the resistor R28, the resistor R206 and the resistor R207, wherein, The MCU is connected to the anode of the primary light emitting diode of the photoelectric coupler U16 through the resistor R16, the cathode of the primary light emitting diode of the photoelectric coupler U16 is grounded, and the output terminal of the photoelectric coupler U16 is connected to the first input pin and the second input pin of the driving chip U17; The first enable terminal of the driving chip U17 is connected to the collector of the secondary light sensitive triode of the photoelectric coupler U3, the second enable terminal of the driving chip U17 is connected to the collector of the secondary light sensitive triode of the photoelectric coupler U6, the first enable terminal is connected to one end of the resistor R27 through the resistor R28, and the other end of the resistor R27 is connected to the second enable terminal; The first output terminal of the driving chip U17 is connected to the gate of the MOS tube Q1 through the resistor R206 and the resistor R2, and the second output terminal of the driving chip U17 is connected to the gate of the MOS tube Q2 through the resistor R207 and the resistor R41.

8. The high reliability solid state relay with pre-charge function of claim 6, wherein, It also includes a voltage detection circuit, the voltage detection circuit includes capacitors C38, C15, C16, C17, C18, C19, C20, C21, photoelectric coupler U10, photoelectric coupler U11, resistor R15, resistor R10, resistor R12, resistor R20, resistor R6, resistor R9, resistor R7, resistor R13, diode D3, diode D12, operational amplifier U2B and operational amplifier U2C, wherein The capacitors C38, C15, C18, C16, C19, C21, C20 and C17 are connected in series between the first connection end and the second connection end of the output circuit, one end of the capacitor C18 and one end of the capacitor C16 are connected to the non-inverting input terminal of the operational amplifier U2B through the resistor R6, and the non-inverting input terminal of the operational amplifier U2B is also grounded through the resistor R9; The inverting input end of the operational amplifier U2B is connected to the power supply voltage VSB1, the output end of the operational amplifier U2B is connected to the cathode of the diode D3 and one end of the resistor R15, the anode of the diode D3 and the other end of the resistor R15 are connected to the anode of the primary light emitting diode of the photoelectric coupler U11, and the cathode of the primary light emitting diode of the photoelectric coupler U11 is connected to the negative power supply voltage VBS2; The collector of the secondary light sensitive triode of the photoelectric coupler U11 is connected to the MCU and connected to the power supply voltage VCC through the resistor R20, and the emitter of the secondary light sensitive triode of the photoelectric coupler U11 is grounded.

9. The high reliability solid state relay with pre-charge function according to claim 8, characterized in that, One end of the capacitor C19 and one end of the capacitor C21 are connected to the non-inverting input end of the operational amplifier U2C through the resistor R7, and the non-inverting input end of the operational amplifier U2C is also grounded through the resistor R13; The inverting input end of the operational amplifier U2C is connected to the power supply voltage VSB1, the output end of the operational amplifier U2C is connected to the cathode of the diode D12 and one end of the resistor R10, the anode of the diode D12 and the other end of the resistor R10 are connected to the anode of the primary light emitting diode of the photoelectric coupler U10, and the cathode of the primary light emitting diode of the photoelectric coupler U10 is connected to the negative power supply voltage VBS2; The collector of the secondary light sensitive triode of the photoelectric coupler U10 is connected to the MCU and connected to the power supply voltage VCC through the resistor R12, and the emitter of the secondary light sensitive triode of the photoelectric coupler U10 is grounded.

10. The high reliability solid state relay with pre-charge function of claim 9, wherein, It also includes a temperature detection circuit, the temperature detection circuit includes a thermistor R31, a photoelectric coupler U9, a resistor R14, a resistor R18, a resistor R19, a resistor R22, a resistor R77, a capacitor C44 and a voltage comparator U8, wherein One end of the thermistor R31 is connected to the power supply voltage VSB1, and the other end of the thermistor R31 is connected to the non-inverting input end of the voltage comparator U8, and the non-inverting input end of the voltage comparator U8 is grounded through the resistor R77; The inverting input end of the voltage comparator U8 is connected to the positive power supply end through the resistor R14, the positive power supply end of the voltage comparator U8 is connected to the power supply voltage VSB1, the negative power supply end of the voltage comparator U8 is grounded, the inverting input end of the voltage comparator U8 is also grounded through the resistor R18, one end of the capacitor C44 is connected to the positive power supply end of the voltage comparator U8, and the other end of the capacitor C44 is grounded; The output end of the voltage comparator U8 is connected to the cathode of the primary light emitting diode of the photoelectric coupler U9, the anode of the primary light emitting diode of the photoelectric coupler U9 is connected to the power supply voltage VSB1 through the resistor R19, the collector of the secondary light sensitive triode of the photoelectric coupler U9 is connected to the MCU and connected to the power supply voltage VCC through the resistor R22, and the emitter of the secondary light sensitive triode of the photoelectric coupler U9 is grounded.

Images