Pulse width modulation electromagnetic lock driving circuit with wide voltage input

Abstract

The utility model relates to a pulse width modulation electromagnetic lock driving circuit with wide voltage input. The pulse width modulation electromagnetic lock driving circuit is characterized by comprising a voltage conversion circuit, an MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) driving circuit, a voltage sampling circuit, a current sampling circuit, a sampling hold circuit and an alarm circuit, the voltage conversion circuit comprises an input voltage VIN, capacitors C1-C9, resistors R1-R4, an inductor L1 and a power supply chip U1; the input voltage VIN is used for providing direct current for an electromagnetic lock coil; the capacitors C4-C7 are connected with an input voltage VIN and are used for filtering; the capacitors C1-C3, the resistors R1-R4 and the inductor are connected with the power supply chip U1 to generate direct current voltage D5V; the electromagnetic lock has the advantages of being high in applicability, low in calorific value and adjustable in power, can adapt to wide voltage input, can reduce energy consumption of the electromagnetic lock, reduces the calorific value of the coil, prolongs the service life, and meanwhile achieves fault early warning of the electromagnetic lock.

Description

Technical Field

[0001] The utility model relates to the technical field of electromagnetic locks, in particular to a pulse width modulation electromagnetic lock driving circuit with wide voltage input. Background Art

[0002] Electromagnetic locks are widely used on platform doors. Electromagnetic locks work on the electromagnetic principle, using electromagnetic coils to generate electromagnetic force, causing the armature or iron core to move, driving the lock hook to move synchronously, locking or opening the sliding doors in the platform doors, and achieving synchronous opening and closing of the subway train doors and sliding doors; at the same time, they prevent the sliding doors from opening unexpectedly, ensuring the personal safety of platform passengers.

[0003] When the electromagnetic lock is powered on and begins operating, the air gap is at its maximum distance, requiring a higher voltage to ensure the hook's proper operation. However, during the hold phase, the air gap is at its minimum distance, requiring only a lower voltage to maintain the hook's lift. Due to these characteristics, some platform door electromagnetic locks utilize a dual power supply mode, initially applying a higher voltage to lift the lock. After the lock's operation is complete and in the hold phase, a lower voltage is applied to maintain the lift state. The switching of the power supply voltage from a higher voltage to a lower voltage generates a large reverse electromotive force across the electromagnetic lock coil, affecting the reliability of the lock. Furthermore, when the power supply voltage is high, the electromagnetic lock coil consumes a lot of power and generates significant heat, which is also prone to failure and reduces the lifespan of the electromagnetic lock.

[0004] The platform doors used on different lines have different power supply modes, and the electromagnetic locks between the lines cannot be interchanged. Utility Model Content

[0005] The purpose of the utility model is to provide an electromagnetic lock drive circuit based on pulse width modulation, which has strong applicability, low heat generation, adjustable power, can adapt to a wide voltage input, can reduce the energy consumption of the electromagnetic lock, reduce the heat generation of the coil, extend the service life, and at the same time realize early warning of electromagnetic lock failure.

[0006] To achieve the above object, the utility model adopts the technical scheme, relates to a wide voltage input's pulse width modulation electromagnetic lock drive circuit, its characterized by: including voltage conversion circuit, MOSFET drive circuit, voltage sampling circuit, current sampling circuit, sample and hold circuit, alarm circuit, voltage conversion circuit includes input voltage VIN, capacitor C1~C9, resistance R1~R4, inductance L1 and power supply chip U1, input voltage VIN is used to provide direct current for electromagnetic lock coil, capacitor C4~C7 is connected with input voltage VIN, is used for filtering, capacitor C1~C3 resistance R1~R4 and inductance are connected with power supply chip U1 and are used to generate direct current voltage D5V, direct current 5V voltage is the power supply of MOSFET drive circuit, voltage sampling circuit, current sampling circuit, sample and hold circuit, alarm circuit, capacitor C8, C9 are connected with direct current voltage D5V, are used for filtering, MOSFET drive circuit includes CPU U2, capacitor C10, resistance R5~R7, PNP triode Q1, MOSFET Q2, schottky diode D1, capacitor C10 is connected with direct current voltage D5V, the base of PNP triode Q1 is electrically connected with resistance R6, emission set is connected with direct current voltage D5V, the collector is connected with resistance R7, the source of MOSFET Q2 is grounded, the gate is connected with R7 and is grounded through resistance R5, the drain is connected with the OUT2 end of electromagnetic lock coil, the positive pole of schottky diode D1 is connected with the OUT2 end of electromagnetic lock coil, and the negative pole is connected with the OUT1 end of electromagnetic lock coil.

[0007] Voltage sampling circuit includes resistance R8~R10, capacitor C13~C14, one end of resistance R8 is connected with the OUT1 end of electromagnetic lock coil, and the other end is connected with resistance R9, the other end of resistance R9 is connected with resistance R10, the other end of resistance R10 is grounded, the parallel connection of capacitor C13 and C14 is connected with the OUT1 end of electromagnetic lock coil, and the other end is grounded, the electric connection point of resistance R9 and resistance R10 is connected with the 5th pin of sample and hold circuit input end through resistance R13, and the sampling voltage is transmitted to the sample and hold circuit.

[0008] Current sampling circuit includes schottky diode D4, capacitor C12, current detection chip U3, the positive pole of schottky diode D4 is connected with input voltage VIN, and the negative pole is connected with the input of current detection chip U3, direct current voltage D5V is connected with the power supply end of current detection chip U3, the power supply positive end of current detection chip U3 is connected with the electric connection point of direct current voltage D5V, and the negative end of current detection chip U3 is connected with capacitor C12, the parallel connection of the 1st pin and the 2nd pin of the current sampling end of current detection chip U3 is connected with the negative pole of schottky diode D4, the parallel connection of the 3rd pin and the 4th pin is connected with the load loop of MOSFET drive circuit, and is used to obtain the load current of MOSFET drive circuit.

[0009] The sampling and holding circuit comprises resistors R11-R14, capacitors C15-C18, Schottky diodes D2-D3 and an operational amplifier U4; one end of the resistor R13 is connected with the voltage sampling circuit, and the other end is connected with Pin5 of the operational amplifier U4; one end of the capacitor C17 is connected with Pin5 of the operational amplifier U4, and the other end is grounded; one end of the resistor R12 is connected with the current sampling circuit, and the other end is connected with Pin3 of the operational amplifier U4; one end of the capacitor C18 is connected with Pin3 of the operational amplifier U4, and the other end is grounded; one end of the resistor R11 is connected with Pin5 and Pin6 of the operational amplifier U4, and the other end is connected with the ADC_VOLTAGE pin of the CPU U2; one end of the resistor R14 is connected with Pin1 and Pin2 of the operational amplifier U4, and the other end is connected with the ADC_CURRENT pin of the CPU U2; one end of the capacitor C11 is connected with the ADC_CURRENT pin of the CPU U2, and the other end is grounded; one end of the capacitor C16 is connected with the ADC_VOLTAGE pin of the CPU U2, and the other end is grounded; the negative electrode of the Schottky diode D2 is connected with the direct current voltage D5V, and the positive electrode is connected with the ADC_CURRENT pin of the CPU U2; the negative electrode of the Schottky diode D3 is connected with the direct current voltage D5V, and the positive electrode is connected with the ADC_VOLTAGE pin of the CPU U2.

[0010] The alarm circuit comprises a resistor R15 and an LED1; one end of the resistor R15 is connected with the LED pin of the CPU U2, and the other end is connected with the negative electrode of the LED1; the positive electrode of the LED1 is connected with the direct current voltage D5V.

[0011] The working principle of the circuit is as follows: when the input end VIN of the electromagnetic lock is V1, the direct current 5V voltage is obtained through the power supply chip U2 to supply power for the CPU; the CPU collects the value of the input voltage VIN through the voltage sampling circuit, and outputs the PWM signal with the duty ratio of Duty1 within 0-t1, at this time, the input voltage is V1, and the voltage difference of the electromagnetic lock coil is △V1, so that the electromagnetic lock is lifted; the PWM signal with the duty ratio of Duty2 is outputted within t1-t2, at this time, the input voltage is V1, and the voltage difference of the electromagnetic lock coil is △V2, so that the lifted state of the electromagnetic lock is maintained; at the t3 moment, the input end VIN of the electromagnetic lock becomes V2, at this time, the CPU outputs the PWM signal with the duty ratio of Duty3, so that the voltage difference of the electromagnetic lock coil is maintained as △V2, and the lifted state of the electromagnetic lock is maintained. The voltage difference of the electromagnetic lock coil can be changed by adjusting the duty ratio of the PWM pulse outputted by the CPU, the power in the maintaining stage is reduced while the electromagnetic lock is lifted, the function of adjustable power is realized, the heat generation of the coil is reduced, the value of the current sampling is compared with the set value by the CPU, and the alarm circuit works when the fault is detected, and the LED is lighted.

[0012] The utility model discloses the following characteristics and advantages have because adopting above technical method,

[0013] 1, strong applicability

[0014] The utility model discloses can be applicable to wide voltage input, can keep the stability of electromagnetic lock coil voltage when input voltage fluctuation,

[0015] 2, low heat, long service life

[0016] The utility model discloses effectively reduced the heat of electromagnetic lock coil, reduced the power of keeping stage, prolonged the service life of electromagnetic lock,

[0017] 3, power adjustable

[0018] Using PWM technology can change the pressure difference of both ends of electromagnetic lock coil through the duty ratio of CPU output pulse, thereby according to the parameter of electromagnetic lock coil and input voltage adjustment power,

[0019] 4, realize the early warning of electromagnetic lock failure

[0020] Through the sampling of electromagnetic lock current, and with the set domain value comparison, can realize the early warning of door lock common fault, including door lock not to fall to the position, attract to not to the position and card stagnation etc. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is the circuit principle diagram of the utility model,

[0022] Figure 2 It is the pressure difference waveform diagram of both ends of electromagnetic lock coil when input voltage VIN changes.

[0023] In the drawing, 1, voltage conversion circuit, 2, MOS drive circuit, 3, voltage sampling circuit, 4, current sampling circuit, 5, sampling holding circuit, 6, alarm circuit, 7, burning circuit. DETAILED DESCRIPTION

[0024] In order to further elaborate the technical means and effects that the invention achieves predetermined purposes, the specific implementation, structural features and effects of the utility model are described in detail as follows in combination with the drawings and examples.

[0025] For example, Figure 1As shown, the utility model relates to a pulse width modulation electromagnetic lock drive circuit with a wide voltage input, which is characterized by: including a voltage conversion circuit 1, a MOSFET drive circuit 2, a voltage sampling circuit 3, a current sampling circuit 4, a sample and hold circuit 5, an alarm circuit 6, and an alarm circuit 7. The voltage conversion circuit 1 includes an input voltage VIN, capacitors C1-C9, resistors R1-R4, an inductor L1 and a power chip U1. The input voltage VIN is used to provide direct current to the electromagnetic lock wire; capacitors C4-C7 are connected to the input voltage VIN for filtering; capacitors C1-C3, resistors R1-R4 and the inductor are connected to the power chip U1 for generating a direct current voltage D5V, which provides a 5V voltage to the MOSFET drive circuit 2, the voltage sampling circuit 3, the current sampling circuit 4, the sample and hold circuit 5, and the alarm circuit 6; capacitors C8 and C9 are connected to the direct current voltage D5V for filtering.

[0026] The CPU in the MOSFET drive circuit 2 is used to generate PWM pulses, and the duty cycle is determined according to the parameters of the electromagnetic lock coil and the input voltage VIN. The MOSFET drive circuit 2 includes a CPU U2, a capacitor C10, resistors R5~R7, a PNP transistor Q1, a MOSFET Q2, and a Schottky diode D1; the capacitor C10 is connected to the DC voltage D5V; the base of the PNP transistor Q1 is electrically connected to the resistor R6, the emitter is connected to the DC voltage D5V, and the collector is connected to the resistor R7; the source of the MOSFET Q2 is grounded, the gate is connected to R7 and grounded through the resistor R5, and the drain is connected to the OUT2 end of the electromagnetic lock coil; the positive pole of the Schottky diode D1 is connected to the OUT2 end of the electromagnetic lock coil, and the negative pole is connected to the OUT1 end of the electromagnetic lock coil.

[0027] The voltage sampling circuit 3 includes resistors R8~R10 and capacitors C13~C14. One end of resistor R8 is connected to the OUT1 end of the electromagnetic lock coil, and the other end is connected to resistor R9; the other end of resistor R9 is connected to resistor R10; the other end of resistor R10 is grounded; the capacitors C13 and C14 are connected in parallel, and one end is connected to the OUT1 end of the electromagnetic lock coil, and the other end is grounded; the electrical connection point between resistors R9 and R10 is electrically connected to the 5th pin of the input end of the sampling and holding circuit 5 through resistor R13, and the sampled voltage is transmitted to the sampling and holding circuit 5.

[0028] The current sampling circuit 4 includes a Schottky diode D4, a capacitor C12, and a current detection chip U3; the positive electrode of the Schottky diode D4 is connected with the input voltage VIN, and the negative electrode is connected with the input of the current detection chip U3; a direct current voltage D5V is connected with the power supply end of the current detection chip U3, the power supply positive end of the current detection chip U3 is connected with the electric connection point of the direct current voltage D5V, and the negative end of the current detection chip U3 is connected with the capacitor C12; the current sampling end of the current detection chip U3 is connected with the negative electrode of the Schottky diode D4 in parallel through the first pin and the second pin, and the third pin and the fourth pin are connected with the load loop of the MOSFET driving circuit 2 in parallel, so as to obtain the load current of the MOSFET driving circuit 2.

[0029] The sampling and holding circuit 5 includes resistors R11-R14, capacitors C15-C18, Schottky diodes D2-D3, and an operational amplifier U4; one end of the resistor R13 is connected with the voltage sampling circuit 3, and the other end is connected with Pin5 of the operational amplifier U4 of the sampling and holding circuit 5; one end of the capacitor C17 is connected with Pin5 of the operational amplifier U4, and the other end is grounded; one end of the resistor R12 is connected with the current sampling circuit 4, and the other end is connected with Pin3 of the operational amplifier U4; one end of the capacitor C18 is connected with Pin3 of the operational amplifier U4, and the other end is grounded; one end of the resistor R11 is connected with Pin5 and Pin6 of the operational amplifier U4, and the other end is connected with the ADC_VOLTAGE pin of the CPU U2; one end of the resistor R14 is connected with Pin1 and Pin2 of the operational amplifier U4, and the other end is connected with the ADC_CURRENT pin of the CPU U2; one end of the capacitor C11 is connected with the ADC_CURRENT pin of the CPU U2, and the other end is grounded; one end of the capacitor C16 is connected with the ADC_VOLTAGE pin of the CPU U2, and the other end is grounded; the negative electrode of the Schottky diode D2 is connected with the direct current voltage D5V, and the positive electrode is connected with the ADC_CURRENT pin of the CPU U2; the negative electrode of the Schottky diode D3 is connected with the direct current voltage D5V, and the positive electrode is connected with the ADC_VOLTAGE pin of the CPU U2.

[0030] The alarm circuit 6 includes a resistor R15 and an LED1; one end of the resistor R15 is connected with the LED pin of the CPU U2, and the other end is connected with the negative electrode of the LED1; the positive electrode of the LED1 is connected with the direct current voltage D5V.

[0031] The burning circuit 7 includes a needle seat CNT1; Pin1 of the needle seat CNT1 is connected with the TXD of the CPU U2, Pin2 is connected with the RXD of the CPU U2, Pin3 is connected with the direct current voltage D5V, and Pin4 is connected with GND.

[0032] As Figure 1 , Figure 2As shown, the voltage conversion circuit 1 obtains the direct current 5V voltage for the CPU through the power supply chip U2; the CPU collects the value of the input voltage VIN through the voltage sampling circuit 3, and outputs the PWM signal with the duty ratio of Duty1 within 0~t1, at this time, the input voltage is V1, and the voltage difference of the electromagnetic lock coil is △V1, which ensures that the electromagnetic lock is lifted; the PWM signal with the duty ratio of Duty2 is outputted within t1~t2, at this time, the input voltage is V1, and the voltage difference of the electromagnetic lock coil is △V2, which maintains the lifted state of the electromagnetic lock; at t3 moment, the input end VIN of the electromagnetic lock becomes V2, at this time, the CPU outputs the PWM signal with the duty ratio of Duty3, so that the voltage difference of the electromagnetic lock coil is maintained as △V2, and the lifted state of the electromagnetic lock is maintained. The duty ratio of the PWM pulse output by the CPU can be adjusted to change the voltage difference of the electromagnetic lock coil, the power in the maintaining stage is reduced while ensuring that the electromagnetic lock is lifted, the power adjustable function is realized, the heat generation of the coil is reduced, and the alarm circuit 6 works when the CPU compares the sampling value of the current sampling circuit 4 with the setting value and detects the fault, and the LED is lighted.

[0033] The utility model discloses a pulse width modulation (PWM) technology is driven electromagnetic lock through MOSFET drive circuit 2, when electromagnetic lock is in the lifted stage, CPU control output pulse's duty ratio provides higher voltage for coil, makes it complete lifted action, when electromagnetic lock lock pin is lifted, through changing CPU output pulse's duty ratio and reducing the voltage difference of electromagnetic lock coil, maintains the lifted state while effectively reducing the heat generation of coil, prolongs the life of electromagnetic lock. Meanwhile, CPU can adjust the duty ratio of output pulse according to input voltage in real time, and realize the stability of electromagnetic lock coil voltage under the condition of wide input voltage.

[0034] The above content is further detailed description of the utility model in combination with specific preferred embodiments, and cannot be determined that the specific implementation of the utility model is limited to these descriptions.

[0035] For ordinary skilled person in the technical field of the utility model, on the premise of not departing from the concept of the utility model, a plurality of simple deductions or substitutions can be made, and all should be regarded as belonging to the protection scope of the utility model.

Claims

1. A pulse width modulation electromagnetic lock drive circuit with wide voltage input, characterized by: It includes a voltage conversion circuit (1), a MOSFET driving circuit (2), a voltage sampling circuit (3), a current sampling circuit (4), a sampling and holding circuit (5), and an alarm circuit (6); the voltage conversion circuit (1) includes an input voltage VIN, capacitors C1 to C9, resistors R1 to R4, an inductor L1, and a power chip U1; The input voltage VIN is used to provide direct current to the electromagnetic lock coil; capacitors C4~C7 are connected to the input voltage VIN for filtering; capacitors C1~C3 resistors R1~R4 and inductors are connected to the power supply chip U1 to generate a direct current voltage D5V; the direct current 5V voltage supplies power to the MOSFET drive circuit (2), the voltage sampling circuit (3), the current sampling circuit (4), the sample and hold circuit (5), and the alarm circuit (6); capacitors C8 and C9 are connected to the direct current voltage D5V for filtering; the MOSFET drive circuit (2) includes CPUU2, capacitor C10, resistors R5~R7, PNP transistor Q1, MOSFET Q2, and Schottky diode D1, and capacitor C10 is connected to the direct current voltage D5V; the base of the PNP transistor Q1 is electrically connected to the resistor R6, the emitter is connected to the direct current voltage D5V, and the collector is connected to the resistor R7; the MOSFET The source of Q2 is grounded, the gate is connected to R7 and grounded through resistor R5, and the drain is connected to the OUT2 end of the electromagnetic lock coil; the positive pole of the Schottky diode D1 is connected to the OUT2 end of the electromagnetic lock coil, and the negative pole is connected to the OUT1 end of the electromagnetic lock coil.

2. The pulse width modulation electromagnetic lock driving circuit with wide voltage input according to claim 1, characterized in that: The voltage sampling circuit (3) includes resistors R8~R10 and capacitors C13~C14, one end of the resistor R8 is connected to the OUT1 end of the electromagnetic lock coil, and the other end is connected to the resistor R9; the other end of the resistor R9 is connected to the resistor R10; the other end of the resistor R10 is grounded; the capacitors C13 and C14 are connected in parallel, and one end is connected to the OUT1 end of the electromagnetic lock coil, and the other end is grounded; the electrical connection point between the resistors R9 and R10 is electrically connected to the 5th pin of the input end of the sampling and holding circuit (5) through the resistor R13, and the sampling voltage is transmitted to the sampling and holding circuit (5).

3. The pulse width modulation electromagnetic lock driving circuit with wide voltage input according to claim 1, characterized in that: The current sampling circuit (4) includes a Schottky diode D4, a capacitor C12, and a current detection chip U3; the positive electrode of the Schottky diode D4 is connected to the input voltage VIN, and the negative electrode is connected to the input of the current detection chip U3; the DC voltage D5V is electrically connected to the power supply terminal of the current detection chip U3, and the positive power supply terminal of the current detection chip U3 and the DC voltage D5V are electrically connected to the negative terminal of the current detection chip U3 and connected to the capacitor C12; the current sampling terminal pin 1 and pin 2 of the current detection chip U3 are electrically connected in parallel to the negative electrode of the Schottky diode D4, and the pin 3 and pin 4 are electrically connected in parallel to the load circuit of the MOSFET drive circuit (2), for obtaining the load current of the MOSFET drive circuit (2).

4. The pulse width modulation electromagnetic lock driving circuit with wide voltage input according to claim 1, characterized in that: The sampling and holding circuit (5) includes resistors R11~R14, capacitors C15~C18, Schottky diodes D2~D3, and an operational amplifier U4; one end of the resistor R13 is connected to the voltage sampling circuit (3), and the other end is connected to Pin5 of the operational amplifier U4; one end of the capacitor C17 is connected to Pin5 of the operational amplifier U4, and the other end is grounded; one end of the resistor R12 is connected to the current sampling circuit, and the other end is connected to Pin3 of the operational amplifier U4; one end of the capacitor C18 is connected to Pin3 of the operational amplifier U4, and the other end is grounded; one end of the resistor R11 is connected to Pin5 and Pin6 of the operational amplifier U4, and the other end is connected to the ADC_VOLTAGE pin of the CPU U2; one end of the resistor R14 is connected to Pin1 and Pin2 of the operational amplifier U4, and the other end is connected to the ADC_CURRENT pin of the CPU U2; one end of the capacitor C11 is connected to the ADC_CURRENT pin of the CPU U2, and the other end is grounded; one end of the capacitor C16 is connected to the CPU The cathode of Schottky diode D2 is connected to DC voltage D5V, and the anode is connected to ADC_CURRENT pin of CPU U2; the cathode of Schottky diode D3 is connected to DC voltage D5V, and the anode is connected to ADC_VOLTAGE pin of CPU U2.

5. The pulse width modulation electromagnetic lock driving circuit with wide voltage input according to claim 1, characterized in that: The alarm circuit (6) includes a resistor R15 and an LED1. One end of the resistor R15 is connected to the LED pin of the CPU U2, and the other end is connected to the cathode of the LED1. The anode of the LED1 is connected to the DC voltage D5V.

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