CN209435471U - A kind of sampling and protection circuit for induction heating power - Google Patents

Abstract

The utility model discloses a kind of sampling for induction heating power and protection circuits; it is related to power protection field; including the voltage sampling circuit, current sampling circuit and protection circuit being connect with dsp chip; protecting circuit includes current foldback circuit, overvoltage crowbar, overheating protection circuit, further includes the load zero passage conversion circuit connecting with voltage sampling circuit and current sampling circuit.The utility model has the advantages that: by protecting circuit to avoid that component is caused to generate failure because of reasons such as overcurrent, over-voltage, overheats, it ensure that system effectiveness.The signal for avoiding high-speed figure processing chip from receiving by voltage sampling circuit is too high or too low, and high-speed figure is caused to handle wafer damage phenomenon；Avoiding high-speed figure from handling chip by current sampling circuit influences the working efficiency that high-speed figure handles chip because receiving invalid value signal.

Description

A kind of sampling and protection circuit for induction heating power

Technical field

The utility model relates to power protection fields, and in particular to a kind of sampling and guarantor for induction heating power Protection circuit.

Background technique

Traditional induction heating power system mostly uses analog control mode, due to the complex circuit of analog circuit, element The disadvantages of easy to aging, drift, along with the development of digital technology and the extensive use of EDA technology, Digital Control is incuding Application in heating has become a kind of trend, has many advantages, such as intelligent control, reliable and stable.

There is the support of high-speed figure processing chip, not only can preferably solve to simulate using digitized control strategy Relevant issues in control, and some control functions relatively difficult to achieve in simulation control are also added, major advantage has: control System is flexible, system upgrade is convenient, only corresponding control algolithm need to be modified, without being changed well to hardware circuit.Separately Outside, the control program of numerical control system is embodied in control program, once associated hardware resource obtains reasonability configuration, is only needed Pass through modification control software or instruction, so that it may improve the control performance of original system, reliability control system improves, is easy to mark Standardization.However, being easy that component is caused to generate failure because of reasons such as overcurrent, over-voltage, overheats in system operation, making system Low efficiency.Also, the signal that high-speed figure processing chip receives may be too high or too low, leads to high-speed figure processing chip damage It is bad, it is also possible to the working efficiency of high-speed figure processing chip is influenced because receiving invalid value signal.

Utility model content

The purpose of this utility model is that: to solve the above problems, guaranteeing system reliability service, provide a kind of for feeling Answer sampling and the protection circuit of heating power supply.

The technical solution adopted in the utility model is as follows:

A kind of sampling and protection circuit for induction heating power, including dsp chip, further include connecting with dsp chip Voltage sampling circuit, current sampling circuit and protection circuit, the protection circuit includes that current foldback circuit, overvoltage protection are electric Road, overheating protection circuit.

It further, further include load zero passage conversion circuit, the load zero passage conversion circuit connects voltage sampling circuit And current sampling circuit, including voltage comparator U1, voltage comparator U1 pin 1 connects resistance R1A, pin 2 connects resistance R2A, 3 connection -12V power supply of pin, pin 4 are separately connected resistance R3A and R4A, pin 5 and the resistance R3A other end and connect jointly Connection+12V power supply afterwards, the resistance R4A other end are separately connected capacitor C1A, NAND gate U2.

Further, the voltage sampling circuit includes resistance R1B, and the resistance R1B other end is separately connected resistance R2B, can Variohm R3B, variable resistance R3B other end ground connection, the resistance R2B other end connect operational amplifier U3 pin 2；Operation is put Big 1 connection resistance R4B of device U3 pin, pin 3 is separately connected resistance C1B and+12V power supply, pin 4 is separately connected operational amplifier U4 pin 1 and the resistance R4B other end, pin 5 are separately connected capacitor C2B and -12V power supply, and capacitor C1B, C2B other end connects Ground；Operational amplifier U4 pin 2,3 connects resistance R5B after connecting jointly, and the resistance R5B other end is separately connected capacitor C3B and two Pole pipe D1B, capacitor C3B, diode D1B are grounded after connecting jointly.

Further, the current sampling circuit includes resistance R6C, and resistance R6C other end connection operational amplifier U5 draws Foot 2, the connection of operational amplifier U5 pin 1 resistance R7C, pin 3 is separately connected resistance C5C and+12V power supply, pin 4 is separately connected Operational amplifier U6 pin 1 and the resistance R7C other end, pin 5 are separately connected capacitor C4C and -12V power supply, and capacitor C5C, C4C are another One end is grounded；Operational amplifier U6 pin 2,3 connects diode D1C after connecting jointly, and diode D1C is separately connected capacitor C6C, resistance R8C, operational amplifier U7 pin 1, capacitor C6C, the resistance R8C other end are grounded after connecting jointly, operational amplifier U7 pin 2,3 connects resistance R9C after connecting jointly, and the resistance R9C other end is separately connected capacitor C7C, diode D2C, capacitor C7C, the diode D2C other end are grounded after connecting jointly.

Further, the current foldback circuit includes voltage comparator U8, and voltage comparator U8 pin 1 connects resistance Variable resistance R1D, diode D1D, capacitor C1D are connected after R2D and are grounded, variable resistance R1D, diode D1D, capacitor The C1D other end connects resistance R8D after connecting jointly；Voltage comparator U8 pin 2 is separately connected resistance R4D, capacitor C2D, two poles Pipe D2D, resistance R4D, the capacitor C2D other end are grounded after connecting jointly, and the diode D2D other end connects capacitor R3D；Voltage compares Device U8 pin 4 is separately connected resistance R5D, R6D, resistance R5D other end connection+12V power supply, and the resistance R6D other end connects optocoupler OP1 pin 1, optocoupler OP1 pin 2,3 are grounded, and optocoupler OP1 pin 4 is grounded after connecting resistance R7D.

Further, the overvoltage crowbar includes voltage comparator U9, and voltage comparator U9 pin 1 connects resistance Variable resistance R1E, diode D1E, capacitor C1E are connected after R2E and are grounded, variable resistance R1E, diode D1E, capacitor The C1E other end connects resistance R9E, resistance R9E other end connection+12V power supply after connecting jointly；Voltage comparator U9 pin 2 connects Resistance R3E, R4E, resistance R4E other end ground connection are separately connected after connecting resistance R5E；Voltage comparator U9 pin 4 is separately connected electricity R6E, R7E, resistance R6E other end connection+12V power supply are hindered, the resistance R7E other end connects optocoupler OP2 pin 1, optocoupler OP2 pin 2, it 3 is grounded, optocoupler OP2 pin 4 is grounded after connecting resistance R8E.

Further, the overheating protection circuit includes operational amplifier U10, and operational amplifier U10 pin 1 is separately connected Resistance R2F, variable resistance R1F, resistance R2F other end ground connection；Operational amplifier U10 pin 2 be separately connected thermistor Rt, Resistance R3F, thermistor Rt other end ground connection；Operational amplifier U10 pin 3 is grounded；Operational amplifier U10 pin 4 connects electricity R4F is hindered, operational amplifier U10 pin 5, resistance R4F, resistance R3F, the variable resistance R1F other end are all connected with+12V power supply.

In conclusion by adopting the above-described technical solution, the beneficial effects of the utility model are:

1, in the utility model, load current sine wave is converted to by square wave by load zero passage conversion circuit, is then sent Enter in dsp chip, burr phenomena is generated due to shake when avoiding waveform pass zero point, improves the stability of system and reliable Property.

2, in the utility model, because the operating voltage of high-speed figure processing chip is generally definite value, so into high speed number The sampled signal amplitude of word processing chip in a certain range, while must add amplitude limiter circuit, in order to avoid too high or too low signal Chip port is handled into high-speed figure, damages chip.

3, in the utility model, the ac current signal that will test by current sensor is by being isolated, following, rectifying filter After wave, obtained signal is become by the smooth effective value signal of direct current by resistance-capacitance circuit in current sampling circuit, is then sent again Chip processing is handled to high-speed figure, improves the working efficiency of high-speed figure processing chip.

4, in the utility model, protection work is executed by protection circuit.When the voltage for being input to voltage comparator U8 is believed Number be more than reference voltage when, voltage comparator U8 export high level, optocoupler OP1 conducting, export low level OIout, indicated Stream occurs, and guarantees the rapidity of overcurrent protection by filter circuit.

5, in the utility model, when the voltage signal for being input to voltage comparator U9 is more than reference voltage, it is input to electricity It presses comparator U9 to export high level, the primary side of optocoupler OP2 is connected, secondary side exports low level OVout, indicates pressure It is raw.

6, in the utility model, radiator is detected as temperature sensor using the thermistor Rt of negative temperature coefficient Temperature, with the rising of temperature, the resistance value of thermistor Rt constantly declines, then the voltage of anode also becomes smaller therewith, when the end OH is defeated Out when low level, ceiling temperature is represented more than, is overheated.When IGBT surface temperature is more than a threshold value, overheating protection circuit is enabled Complete machine is protected.

Detailed description of the invention

It, below will be to use required in embodiment in order to illustrate more clearly of the technical solution of the utility model embodiment Attached drawing be briefly described, it should be understood that the following drawings illustrates only some embodiments of the utility model, therefore should not be by Regard the restriction to range as, for those of ordinary skill in the art, without creative efforts, may be used also To obtain other relevant attached drawings according to these attached drawings.

Fig. 1 is the voltage sampling circuit figure of the utility model；

Fig. 2 is the current sampling circuit figure of the utility model；

Fig. 3 is the current foldback circuit figure of the utility model；

Fig. 4 is the overvoltage crowbar figure of the utility model；

Fig. 5 is the overheating protection circuit figure of the utility model；

Fig. 6 is the load zero passage conversion circuit figure of the utility model.

Specific embodiment

In order to make the purpose of the utility model, technical solutions and advantages more clearly understood, below in conjunction with attached drawing and implementation Example, the present invention will be further described in detail.It should be appreciated that specific embodiment described herein is only to explain this Utility model is not used to limit the utility model, i.e., the described embodiments are only a part of the embodiments of the utility model, Instead of all the embodiments.The component of the utility model embodiment being usually described and illustrated herein in the accompanying drawings can be with each Different configurations is planted to arrange and design.Therefore, the detailed of the embodiments of the present invention provided in the accompanying drawings is retouched below The range for being not intended to limit claimed invention is stated, but is merely representative of the selected embodiment of the utility model. Based on the embodiments of the present invention, those skilled in the art are obtained all without making creative work Other embodiments are fallen within the protection scope of the utility model.

It should be noted that the relational terms of term " first " and " second " or the like be used merely to an entity or Operation is distinguished with another entity or operation, and without necessarily requiring or implying between these entities or operation, there are any This actual relationship or sequence.Moreover, the terms "include", "comprise" or its any other variant be intended to it is non-exclusive Property include so that include a series of elements process, method, article or equipment not only include those elements, but also Further include other elements that are not explicitly listed, or further include for this process, method, article or equipment it is intrinsic Element.In the absence of more restrictions, the element limited by sentence " including one ... ", it is not excluded that including institute State in the process, method, article or equipment of element that there is also other identical elements.

The feature of the utility model and performance are described in further detail with reference to embodiments.

Embodiment 1

A kind of sampling and protection circuit for induction heating power that the utility model preferred embodiment provides, including Dsp chip further includes the voltage sampling circuit connecting with dsp chip, current sampling circuit, protection circuit and load zero passage conversion Circuit, protection circuit include current foldback circuit, overvoltage crowbar, overheating protection circuit, and dsp chip connects transformer.

Wherein:

Load zero passage conversion circuit connection voltage sampling circuit and current sampling circuit, including voltage comparator U1, voltage Comparator U1 pin 1 connects resistance R1A, pin 2 connects resistance R2A, 3 connection -12V power supply of pin, pin 4 and is separately connected resistance Connection+12V power supply after R3A and R4A, pin 5 and the resistance R3A other end connect jointly, the resistance R4A other end are separately connected capacitor C1A, NAND gate U2.

Voltage sampling circuit includes resistance R1B, and the resistance R1B other end is separately connected resistance R2B, variable resistance R3B, can Variohm R3B other end ground connection, the resistance R2B other end connect operational amplifier U3 pin 2；Operational amplifier U3 pin 1 connects Connecting resistance R4B, pin 3 are separately connected resistance C1B and+12V power supply, pin 4 is separately connected operational amplifier U4 pin 1 and resistance The R4B other end, pin 5 are separately connected capacitor C2B and -12V power supply, and capacitor C1B, C2B other end is grounded；Operational amplifier U4 Pin 2,3 connects resistance R5B after connection jointly, and the resistance R5B other end is separately connected capacitor C3B and diode D1B, capacitor C3B, Diode D1B is grounded after connecting jointly.

Current sampling circuit includes resistance R6C, and the resistance R6C other end connects operational amplifier U5 pin 2, operational amplifier The connection of U5 pin 1 resistance R7C, pin 3 is separately connected resistance C5C and+12V power supply, pin 4 is separately connected operational amplifier U6 and draws Foot 1 and the resistance R7C other end, pin 5 are separately connected capacitor C4C and -12V power supply, and capacitor C5C, C4C other end is grounded；Fortune It calculates and connects diode D1C after amplifier U6 pin 2,3 connects jointly, diode D1C is separately connected capacitor C6C, resistance R8C, fortune Amplifier U7 pin 1 is calculated, capacitor C6C, the resistance R8C other end are grounded after connecting jointly, and operational amplifier U7 pin 2,3 connects jointly Resistance R9C is connected after connecing, the resistance R9C other end is separately connected capacitor C7C, diode D2C, and capacitor C7C, diode D2C are another It is grounded after the common connection in end.

Current foldback circuit includes voltage comparator U8, and connection can power transformation after voltage comparator U8 pin 1 connects resistance R2D Resistance device R1D, diode D1D, capacitor C1D are simultaneously grounded, and variable resistance R1D, diode D1D, the capacitor C1D other end connect jointly Resistance R8D is connected afterwards；Voltage comparator U8 pin 2 is separately connected resistance R4D, capacitor C2D, diode D2D, resistance R4D, capacitor The C2D other end is grounded after connecting jointly, and the diode D2D other end connects capacitor R3D；Voltage comparator U8 pin 4 is separately connected Resistance R5D, R6D, resistance R5D other end connection+12V power supply, the resistance R6D other end connect optocoupler OP1 pin 1, and optocoupler OP1 draws Foot 2,3 is grounded, and optocoupler OP1 pin 4 is grounded after connecting resistance R7D.

Overvoltage crowbar includes voltage comparator U9, and connection can power transformation after voltage comparator U9 pin 1 connects resistance R2E Resistance device R1E, diode D1E, capacitor C1E are simultaneously grounded, and variable resistance R1E, diode D1E, the capacitor C1E other end connect jointly Resistance R9E, resistance R9E other end connection+12V power supply are connected afterwards；Voltage comparator U9 pin 2 connects respectively after connecting resistance R5E Connecting resistance R3E, R4E, resistance R4E other end ground connection；Voltage comparator U9 pin 4 is separately connected resistance R6E, R7E, resistance R6E Other end connection+12V power supply, the resistance R7E other end connect optocoupler OP2 pin 1, and optocoupler OP2 pin 2,3 is grounded, optocoupler OP2 Pin 4 is grounded after connecting resistance R8E.

Overheating protection circuit includes operational amplifier U10, and operational amplifier U10 pin 1 is separately connected resistance R2F, can be changed Resistor R1F, resistance R2F other end ground connection；Operational amplifier U10 pin 2 is separately connected thermistor Rt, resistance R3F, temperature-sensitive Resistance Rt other end ground connection；Operational amplifier U10 pin 3 is grounded；Operational amplifier U10 pin 4 connects resistance R4F, and operation is put Big device U10 pin 5, resistance R4F, resistance R3F, the variable resistance R1F other end are all connected with+12V power supply.

Load voltage electric current need to could be captured after waveform convertion circuit conversion is square wave by dsp chip, pass through load Its sine wave is converted to square wave by zero passage conversion circuit, is then fed into dsp chip.As shown in fig. 6, load current is through voltage ratio Compared with square wave is obtained after device LM339, subsequent filtering and the addition of schmidt trigger NAND gate 74LS14 can prevent waveform pass zero point When due to shake generate burr phenomena.The sample circuit of DC output voltage as shown in Figure 1, voltage sensor (LV25-P) every The linear ratio relation for first having to adjust input with output from the signal to come with detection, because the operating voltage of dsp chip is 3.3V so the sampled signal amplitude into dsp chip must be between 0~3.3V, while adding amplitude limiter circuit, so as not to it is excessively high Or cross low signal and enter the port DSP, damage chip.Voltage signal is input to an A/ of dsp chip after following filtering processing The port D is sampled.Inverter output current is sine wave, and sample circuit is as shown in Figure 2.By current sensor (LA305- S by being isolated, following, after rectifying and wave-filtering, become smooth direct current by resistance-capacitance circuit has the ac current signal that) will test Then valid value signal gives dsp chip processing again.

Complete machine is high level, when a failure occurs it, becomes low level when operating normally.When for low level, pass through Circuit is protected to execute protection work.Specifically: current foldback circuit as shown in figure 3, by Hall sensor detect DC side electric current, And current signal is converted into voltage signal OIin, voltage comparator LM339 is sent into compared with reference voltage.When more than benchmark electricity When pressure, voltage comparator LM339 exports high level, and optocoupler OP1 conducting exports low level OIout, indicates overcurrent, leads to Filter circuit is crossed to guarantee the rapidity of overcurrent protection.

Start overvoltage crowbar when inverter input terminal voltage is more than setting value, physical circuit is as shown in Figure 4.From inverse The input terminal for becoming device obtains voltage signal OVin, compared with the reference voltage signal of voltage comparator LM339 input terminal.When super When crossing reference voltage, high level is exported, the primary side of optocoupler OP2 is connected, secondary side exports low level OVout, indicates Pressure is raw.

Switching tube is during turning on and off in inverter and its conducting resistance exists, and IGBT is made to generate power loss, These power consumptions are distributed with form of thermal energy, increase IGBT temperature, to influence its current-carrying capability.The overheat of device in order to prevent, Overheating protection circuit is designed, when IGBT surface temperature is more than a threshold value, enabling overheating protection circuit.As shown in figure 5, using negative The thermistor Rt of temperature coefficient (NTC) detects the temperature of radiator as temperature sensor, with the rising of temperature, temperature-sensitive The resistance value of resistance Rt constantly declines, then the voltage of anode also becomes smaller therewith, and when U+ is less than U-, the end OH exports low level, indicates More than ceiling temperature, overheat.Wherein, ceiling temperature is set by adjusting R1F.

The above is only the preferred embodiment of the utility model only, is not intended to limit the utility model, all at this Made any modifications, equivalent replacements, and improvements etc., should be included in the utility model within the spirit and principle of utility model Protection scope within.

Claims (7)

1. a kind of sampling and protection circuit for induction heating power, including dsp chip, it is characterised in that: further include and DSP Voltage sampling circuit, current sampling circuit and the protection circuit of chip connection, the protection circuit includes current foldback circuit, mistake Voltage protection circuit, overheating protection circuit.

2. a kind of sampling and protection circuit for induction heating power according to claim 1, it is characterised in that: also wrap Include load zero passage conversion circuit, the load zero passage conversion circuit connection voltage sampling circuit and current sampling circuit, including electricity Comparator U1 is pressed, voltage comparator U1 pin 1 connects resistance R1A, pin 2 connects resistance R2A, 3 connection -12V power supply of pin, draws Connection+12V power supply after foot 4 is separately connected resistance R3A and R4A, pin 5 and the resistance R3A other end connect jointly, resistance R4A are another One end is separately connected capacitor C1A, NAND gate U2.

3. a kind of sampling and protection circuit for induction heating power according to claim 1 or 2, it is characterised in that: The voltage sampling circuit includes resistance R1B, and the resistance R1B other end is separately connected resistance R2B, variable resistance R3B, can power transformation Device R3B other end ground connection is hindered, the resistance R2B other end connects operational amplifier U3 pin 2；Operational amplifier U3 pin 1 connects electricity Resistance R4B, pin 3 is separately connected resistance C1B and+12V power supply, pin 4 is separately connected operational amplifier U4 pin 1 and resistance R4B The other end, pin 5 are separately connected capacitor C2B and -12V power supply, and capacitor C1B, C2B other end is grounded；Operational amplifier U4 draws Foot 2,3 connects resistance R5B after connecting jointly, and the resistance R5B other end is separately connected capacitor C3B and diode D1B, capacitor C3B, two Pole pipe D1B is grounded after connecting jointly.

4. a kind of sampling and protection circuit for induction heating power according to claim 1 or 2, it is characterised in that: The current sampling circuit includes resistance R6C, and the resistance R6C other end connects operational amplifier U5 pin 2, and operational amplifier U5 draws The connection of foot 1 resistance R7C, pin 3 is separately connected resistance C5C and+12V power supply, pin 4 is separately connected operational amplifier U6 pin 1 It is separately connected capacitor C4C and -12V power supply with the resistance R7C other end, pin 5, capacitor C5C, C4C other end is grounded；Operation is put Big device U6 pin 2,3 connects diode D1C after connection jointly, and diode D1C is separately connected capacitor C6C, resistance RSC, operation are put Big device U7 pin 1, capacitor C6C, the resistance R8C other end are grounded after connecting jointly, and operational amplifier U7 pin 2,3 is jointly after connection Resistance R9C is connected, the resistance R9C other end is separately connected capacitor C7C, diode D2C, and capacitor C7C, the diode D2C other end are total It is grounded after same connection.

5. a kind of sampling and protection circuit for induction heating power according to claim 1, it is characterised in that: described Current foldback circuit includes voltage comparator U8, voltage comparator U8 pin 1 connect connect after resistance R2D variable resistance R1D, Diode D1D, capacitor C1D are simultaneously grounded, and variable resistance R1D, diode D1D, the capacitor C1D other end connect electricity after connecting jointly Hinder R8D；Voltage comparator U8 pin 2 is separately connected resistance R4D, capacitor C2D, diode D2D, and resistance R4D, capacitor C2D are another It is grounded after the common connection in end, the diode D2D other end connects capacitor R3D；Voltage comparator U8 pin 4 be separately connected resistance R5D, R6D, resistance R5D other end connection+12V power supply, the resistance R6D other end connect optocoupler OP1 pin 1, and optocoupler OP1 pin 2,3 is equal Ground connection, optocoupler OP1 pin 4 are grounded after connecting resistance R7D.

6. a kind of sampling and protection circuit for induction heating power according to claim 1, it is characterised in that: described Overvoltage crowbar includes voltage comparator U9, voltage comparator U9 pin 1 connect connect after resistance R2E variable resistance R1E, Diode D1E, capacitor C1E are simultaneously grounded, and variable resistance R1E, diode D1E, the capacitor C1E other end connect electricity after connecting jointly Hinder R9E, resistance R9E other end connection+12V power supply；Voltage comparator U9 pin 2 is separately connected resistance after connecting resistance R5E R3E, R4E, resistance R4E other end ground connection；Voltage comparator U9 pin 4 is separately connected resistance R6E, R7E, the resistance R6E other end Connection+12V power supply, the resistance R7E other end connect optocoupler OP2 pin 1, and optocoupler OP2 pin 2,3 is grounded, optocoupler OP2 pin 4 It is grounded after connection resistance R8E.

7. a kind of sampling and protection circuit for induction heating power according to claim 1, it is characterised in that: described Overheating protection circuit includes operational amplifier U10, and operational amplifier U10 pin 1 is separately connected resistance R2F, variable resistance R1F, resistance R2F other end ground connection；Operational amplifier U10 pin 2 is separately connected thermistor Rt, resistance R3F, thermistor Rt Other end ground connection；Operational amplifier U10 pin 3 is grounded；Operational amplifier U10 pin 4 connects resistance R4F, operational amplifier U10 Pin 5, resistance R4F, resistance R3F, the variable resistance R1F other end are all connected with+12V power supply.