Solenoid valve system based on CAN bus and constant current PWM control

Abstract

The invention relates to the technical field of automatic control, in particular to an electromagnetic valve system based on a CAN bus and constant-current PWM control. The system comprises an electromagnetic valve executing mechanism, a CAN bus communication module, a constant-current PWM control circuit, an MCU and an electromagnetic valve system. According to the technical scheme, square wave signals with different duty ratios are generated as reference voltage signals according to needs, the detection voltage Vi is monitored to monitor the load current ILoad, the requirement of an upper computer is received through the CAN communication module, the square wave signals with the needed duty ratio are generated, whether the fly-wheel diode is connected to a loop or not is selected, and the control over the load current ILoad is achieved. The MCU feeds back state information such as load current ILoad and the like to an upper computer through a CAN communication module, so that accurate control is realized.

Description

Technical Field

[0001] The invention relates to the technical field of automatic control, and in particular to a solenoid valve system based on CAN bus and constant current PWM control. Background Art

[0002] In industrial automation control systems, solenoid valves are important actuators, and their control accuracy, stability and energy efficiency directly affect the performance of the entire system.

[0003] The prior art, CN2018109421659, is a solenoid valve control system and method, which can only realize switching by impact through remote control of the needle valve assembly. However, when used in conjunction with the CAN bus and constant current PWM control, there are deficiencies in signal transmission, control accuracy and energy efficiency.

[0004] Therefore, it is necessary to design a solenoid valve system based on CAN bus and constant current PWM control to solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to provide a solenoid valve system based on CAN bus and constant current PWM control to overcome the above-mentioned deficiencies in the current prior art.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A solenoid valve system based on CAN bus and constant current PWM control, characterized in that it includes a solenoid valve actuator, a CAN bus communication module, a constant current PWM control circuit and an MCU, and a solenoid valve system;

[0008] Solenoid valve actuator: It includes valve body, valve core, moving iron block, magnetic limit device and ceramic wear-resistant layer, which is responsible for switching the medium on and off according to the control signal;

[0009] CAN bus communication module: responsible for the remote communication between the solenoid valve system and the MCU, realizing the sending of control instructions and the receiving of status feedback;

[0010] Constant current PWM control circuit: Generates constant current PWM control signal to accurately control the current of the solenoid valve coil and realize accurate opening and closing of the valve core;

[0011] MCU: responsible for the control and monitoring of the entire system, receiving instructions from sensors or user interfaces, sending control signals to the solenoid valve system through the CAN bus, and receiving status feedback for real-time monitoring;

[0012] The solenoid valve system includes a switch circuit, one end of the switch circuit is connected to a current detection circuit, the other end of the switch circuit is connected to a hysteresis comparison circuit, the current detection circuit is externally connected to a solenoid valve coil L1, a freewheeling circuit 3 interconnected with the current detection circuit, the hysteresis comparison circuit is externally connected to a filter circuit, an MCU interconnected with the filter circuit, the freewheeling circuit, the current detection circuit and the hysteresis comparison circuit, and a CAN communication module interconnected with the MCU;

[0013] The switch circuit is connected to the solenoid valve coil L1, and the on and off of the switch circuit is controlled by the output duty cycle signal VD of the hysteresis comparison circuit;

[0014] The current detection circuit is used to detect the load current ILoad passing through the solenoid valve coil L1, and output a detection voltage Vi proportional to the load current ILoad;

[0015] The freewheeling circuit is used to provide a current path for the solenoid valve coil L1 and the current detection circuit when the switch circuit is disconnected;

[0016] The first input end of the hysteresis comparison circuit is connected to the output end of the current detection circuit, the second input end of the hysteresis comparison circuit is connected to the reference voltage vREF, and the output end of the hysteresis comparison circuit is connected to the control end of the switch circuit to control the on and off of the switch circuit;

[0017] The filter circuit is a low-pass filter circuit composed of resistors and capacitors. The filter circuit filters the square wave signal generated by the MCU into a stable DC reference voltage.

[0018] Preferably, the switch circuit is a high-side switch, a first conduction end of the high-side switch is connected to a power source vin, a second conduction end of the high-side switch is connected to a current detection circuit, and the switch circuit 1 is an internal integrated power switch device provided with an integrated circuit chip.

[0019] Preferably, the current detection circuit includes a current sampling resistor R1 and an amplifier circuit U1, the current sampling resistor R1 is connected in series with the solenoid valve coil L1, the input end of the amplifier circuit U1 is respectively connected to the two ends of the current sampling resistor R1, and the output end of the amplifier circuit U1 is connected to the first input end of the hysteresis comparator circuit.

[0020] Preferably, the freewheeling circuit includes a freewheeling diode and an integrated circuit chip U4 that integrates a power switching device; the cathode of the freewheeling diode is respectively connected to the solenoid valve coil and one end of the current sampling resistor R1, the anode of the freewheeling diode D1 is connected to the second conduction end of the freewheeling switch U4, the first conduction end of the freewheeling switch U4 is connected to the ground end of the solenoid valve coil, and the conduction and shutdown of the freewheeling switch U4 are controlled by the MCU freewheeling loop control signal Vfc.

[0021] Preferably, the first input terminal and the second input terminal of the hysteresis comparison circuit are an inverting input terminal and a non-inverting input terminal respectively.

[0022] Preferably, the MCU is responsible for the control and monitoring of the system, generates square wave signals with different duty cycles as reference voltage signals as needed, monitors the detection voltage to monitor the load current, receives the needs of the host computer through the CAN communication module, generates a square wave signal with the required duty cycle, and selects whether to connect the freewheeling diode to the loop. The MCU also feeds back status information such as the load current to the host computer through the CAN communication module.

[0023] The beneficial effects of the present invention are as follows: the technical solution generates square wave signals with different duty cycles as reference voltage signals as needed, monitors the detection voltage Vi to monitor the load current ILoad, receives the needs of the host computer through the CAN communication module, generates a square wave signal with the required duty cycle, and selects whether to connect the freewheeling diode to the loop. At the same time, the MCU feeds back status information such as the load current ILoad to the host computer through the CAN communication module, thereby achieving precise control. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of a solenoid valve system based on CAN bus and constant current PWM control of the present invention;

[0025] Figure 2 It is a schematic diagram of a regulating component of a solenoid valve system based on CAN bus and constant current PWM control of the present invention;

[0026] In the figure: 1. Switching circuit; 2. Current detection circuit; 4. Hysteresis comparison circuit; 3. Freewheeling circuit; 5. Filter circuit. DETAILED DESCRIPTION

[0027] Reference Figure 1 to Figure 2 , a solenoid valve system based on CAN bus and constant current PWM control, which includes a solenoid valve actuator, a CAN bus communication module, a constant current PWM control circuit and an MCU, and a solenoid valve system;

[0028] Solenoid valve actuator: It includes valve body, valve core, moving iron block, magnetic limit device and ceramic wear-resistant layer, which is responsible for switching the medium on and off according to the control signal;

[0029] CAN bus communication module: responsible for the remote communication between the solenoid valve system and the MCU, realizing the sending of control instructions and the receiving of status feedback;

[0030] Constant current PWM control circuit: Generates constant current PWM control signal to accurately control the current of the solenoid valve coil and realize accurate opening and closing of the valve core;

[0031] MCU: responsible for the control and monitoring of the entire system, receiving instructions from sensors or user interfaces, sending control signals to the solenoid valve system through the CAN bus, and receiving status feedback for real-time monitoring;

[0032] The solenoid valve system includes a switch circuit 1, one end of the switch circuit 1 is connected to a current detection circuit 2, the other end of the switch circuit 1 is connected to a hysteresis comparison circuit 4, the current detection circuit 2 is externally connected to a solenoid valve coil L1, a freewheeling circuit 3 interconnected with the current detection circuit, the hysteresis comparison circuit 4 is externally connected to a filter circuit 5, an MCU interconnected with the filter circuit 5, the freewheeling circuit 3, the current detection circuit 2 and the hysteresis comparison circuit 4, and a CAN communication module interconnected with the MCU;

[0033] The switch circuit 1 is connected to the solenoid valve coil L1 , and the on and off of the switch circuit 1 is controlled by the output duty cycle signal VD of the hysteresis comparison circuit 4 .

[0034] The current detection circuit 2 is used to detect the load current ILoad passing through the solenoid valve coil L1 and output a detection voltage Vi proportional to the load current ILoad.

[0035] The freewheeling circuit 3 is used to provide a current path for the solenoid valve coil L1 and the current detection circuit 2 when the switch circuit 1 is disconnected.

[0036] The first input terminal and the second input terminal of the hysteresis comparison circuit 4 are respectively an inverting input terminal and a non-inverting input terminal;

[0037] The freewheeling circuit includes a freewheeling diode D1 and an integrated circuit chip U4 integrating a power switch device.

[0038] In the specific connection mode of this embodiment, the switch circuit 1 is a high-side switch, the first conduction end of the high-side switch is connected to the power supply vin, and the second conduction end of the high-side switch is connected to the current detection circuit 2. In a specific embodiment, the switch circuit 1 is an integrated circuit chip U3 with a power switch device integrated inside; the current detection circuit 2 includes a current sampling resistor R1 and an amplifier circuit U1, the current sampling resistor R1 is connected in series with the solenoid valve coil L1, the input end of the amplifier circuit U1 is respectively connected to the two ends of the current sampling resistor R1, and the output end of the amplifier circuit U1 is connected to the first input end of the hysteresis comparison circuit 4; The cathode of the freewheeling diode D1 is connected to the solenoid valve coil and one end of the current sampling resistor R1 respectively, the anode of the freewheeling diode D1 is connected to the second conduction end of the freewheeling switch U4, the first conduction end of the freewheeling switch U4 is connected to the ground end of the solenoid valve coil, and the on and off of the freewheeling switch U4 is controlled by the MCU freewheeling loop control signal Vfc; the first input end of the hysteresis comparison circuit 4 is connected to the output end of the current detection circuit 2, the second input end of the hysteresis comparison circuit 4 is connected to the reference voltage vREF, and the output end of the hysteresis comparison circuit 4 is connected to the control end of the switch circuit 1 to control the on and off of the switch circuit 1. The filter circuit 5 is an RC low-pass filter circuit composed of a resistor R4 and a capacitor C1, and the filter circuit 5 filters the square wave signal generated by the MCU into a stable DC reference voltage VREF.

[0039] The benefits of the present invention are that the technical solution generates square wave signals with different duty cycles as reference voltage signals as needed, monitors the detection voltage Vi to monitor the load current ILoad, receives the needs of the host computer through the CAN communication module, generates a square wave signal with the required duty cycle, and selects whether to connect the freewheeling diode to the loop. At the same time, the MCU feeds back status information such as the load current ILoad to the host computer through the CAN communication module, thereby achieving precise control.

[0040] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A solenoid valve system based on CAN bus and constant current PWM control, characterized in that: It includes a solenoid valve actuator, a CAN bus communication module, a constant current PWM control circuit and an MCU, and a solenoid valve system; Solenoid valve actuator: It includes valve body, valve core, moving iron block, magnetic limit device and ceramic wear-resistant layer, which is responsible for switching the medium on and off according to the control signal; CAN bus communication module: responsible for the remote communication between the solenoid valve system and the MCU, realizing the sending of control instructions and the receiving of status feedback; Constant current PWM control circuit: Generates constant current PWM control signal to accurately control the current of the solenoid valve coil and realize accurate opening and closing of the valve core; MCU: responsible for the control and monitoring of the entire system, receiving instructions from sensors or user interfaces, sending control signals to the solenoid valve system through the CAN bus, and receiving status feedback for real-time monitoring; The solenoid valve system includes a switch circuit, one end of the switch circuit is connected to a current detection circuit, the other end of the switch circuit is connected to a hysteresis comparison circuit, the current detection circuit is externally connected to a solenoid valve coil L1, a freewheeling circuit 3 interconnected with the current detection circuit, the hysteresis comparison circuit is externally connected to a filter circuit, an MCU interconnected with the filter circuit, the freewheeling circuit, the current detection circuit and the hysteresis comparison circuit, and a CAN communication module interconnected with the MCU; The switch circuit is connected to the solenoid valve coil L1, and the on and off of the switch circuit is controlled by the output duty cycle signal VD of the hysteresis comparison circuit; The current detection circuit is used to detect the load current ILoad passing through the solenoid valve coil L1, and output a detection voltage Vi proportional to the load current ILoad; The freewheeling circuit is used to provide a current path for the solenoid valve coil L1 and the current detection circuit when the switch circuit is disconnected; The first input end of the hysteresis comparison circuit is connected to the output end of the current detection circuit, the second input end of the hysteresis comparison circuit is connected to the reference voltage vREF, and the output end of the hysteresis comparison circuit is connected to the control end of the switch circuit to control the on and off of the switch circuit; The filter circuit is a low-pass filter circuit composed of resistors and capacitors. The filter circuit filters the square wave signal generated by the MCU into a stable DC reference voltage.

2. The solenoid valve system based on CAN bus and constant current PWM control according to claim 1 is characterized in that: The switch circuit is a high-side switch, a first conduction end of the high-side switch is connected to a power source vin, a second conduction end of the high-side switch is connected to a current detection circuit, and the switch circuit 1 is an internal integrated power switch device provided with an integrated circuit chip.

3. The solenoid valve system based on CAN bus and constant current PWM control according to claim 1 is characterized in that: The current detection circuit includes a current sampling resistor R1 and an amplifier circuit U1. The current sampling resistor R1 is connected in series with the solenoid valve coil L1. The input end of the amplifier circuit U1 is respectively connected to the two ends of the current sampling resistor R1. The output end of the amplifier circuit U1 is connected to the first input end of the hysteresis comparison circuit.

4. The solenoid valve system based on CAN bus and constant current PWM control according to claim 1 is characterized in that: The freewheeling circuit includes a freewheeling diode and an integrated circuit chip U4 that integrates a power switching device; the cathode of the freewheeling diode is respectively connected to the solenoid valve coil and one end of the current sampling resistor R1, the anode of the freewheeling diode D1 is connected to the second conduction end of the freewheeling switch U4, the first conduction end of the freewheeling switch U4 is connected to the ground end of the solenoid valve coil, and the conduction and shutdown of the freewheeling switch U4 are controlled by the MCU freewheeling loop control signal Vfc.

5. The solenoid valve system based on CAN bus and constant current PWM control according to claim 1, characterized in that: The first input terminal and the second input terminal of the hysteresis comparison circuit are an inverting input terminal and a non-inverting input terminal respectively.

6. The solenoid valve system based on CAN bus and constant current PWM control according to claim 1, characterized in that: The MCU is responsible for the control and monitoring of the system. It generates square wave signals with different duty cycles as reference voltage signals as needed, monitors the detection voltage to monitor the load current, receives the needs of the host computer through the CAN communication module, generates a square wave signal with the required duty cycle, and chooses whether to connect the freewheeling diode to the loop. The MCU also feeds back status information such as load current to the host computer through the CAN communication module.

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