Induction heating power supply control system

Abstract

The invention discloses an induction heating power supply control system, and relates to the technical field of power supply control. The system comprises a control unit which is used for collecting the current temperature, determining the duty ratio based on a PI regulator, and generating an inversion pulse driving signal according to the duty ratio and the output frequency of a phase-locked loop; the inverter pulse driving signal is used for controlling an inverter bridge; the heating unit is connected with the control unit and is used for executing corresponding actions according to the inversion pulse driving signal so as to realize induction heating power supply control; the circuit protection device is respectively connected with the control unit and a load and is used for carrying out overcurrent and overvoltage protection according to an external input protection signal and cutting off a power supply to protect the system from being damaged; and the visual equipment is connected with the control unit, and is used for generating a visual chart according to the collected temperature signal and power and frequency signals, and inputting the visual chart into docking equipment of a worker for real-time dynamic display. According to the invention, accurate temperature control can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply control, and in particular to an induction heating power supply control system. Background Art

[0002] As an efficient and environmentally friendly heating method, induction heating technology has been widely used in metal heat treatment, smelting, welding, and other fields. As the core component of induction heating technology, the performance of the induction heating power supply control system is directly related to heating efficiency, temperature control accuracy, and system safety.

[0003] However, existing induction heating power supply control systems still have some shortcomings. Traditional induction heating power supply control systems usually use analog circuits for temperature control and circuit protection, which have defects such as low temperature control accuracy and slow circuit protection response speed. Summary of the Invention

[0004] The object of the present invention is to provide an induction heating power supply control system capable of achieving precise temperature control.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] An induction heating power supply control system, comprising:

[0007] A control unit is used to collect the current temperature, determine the duty cycle based on the PI regulator, and generate an inverter pulse drive signal according to the duty cycle and the phase-locked loop output frequency; the inverter pulse drive signal is used to control the inverter bridge;

[0008] a heating unit connected to the control unit and configured to perform corresponding actions according to the inverter pulse drive signal to realize induction heating power supply control;

[0009] A circuit protection device, connected to the control unit and the load, respectively, for performing overcurrent and overvoltage protection according to an external input protection signal, and cutting off the power supply to protect the system from damage;

[0010] A visual device is connected to the control unit and is used to generate a visual chart based on the collected temperature signal and power and frequency signals, and input the visual chart into the staff's docking device for real-time dynamic display.

[0011] Optionally, the heating unit specifically includes: V1 thyristor, V2 thyristor, V3 thyristor, V4 thyristor, V5 thyristor, V6 thyristor, filter capacitor C ZK , inverter bridge and LLC resonant circuit;

[0012] The V1 thyristor and the V4 thyristor are connected in series to form a first parallel branch, the V3 thyristor and the V6 thyristor form a second parallel branch, and the V5 thyristor and the V2 thyristor form a third parallel branch. The first parallel branch, the second parallel branch, the third parallel branch, and the filter capacitor C ZK The inverter bridge is connected in parallel with the LLC resonant circuit.

[0013] Optionally, the inverter bridge is composed of four IGBTs forming an H bridge.

[0014] Optionally, the LLC resonant circuit specifically includes: a resonant inductor L S , resonant capacitor C L , load inductance L L and the load resistor R L ;

[0015] Wherein, the resonant inductor L S One end of the resonant inductor L is connected to the current output end of the inverter bridge. S The other end of the resonant capacitor C L and the load inductance L L One end of the load inductor L L The other end of the load resistor R L One end of the resonant capacitor C L and the load resistor R L The other end of each is connected to the current input end of the inverter bridge.

[0016] Optionally, the control unit specifically includes:

[0017] A temperature collection device, used to collect current temperature;

[0018] The control element is used for: when the three-phase AC power undergoes uncontrolled full-wave rectification to obtain a rectified voltage, after capacitor filtering to obtain a DC voltage, and then after passing through the IGBT inverter bridge to obtain an inverter voltage applied to the LLC resonant circuit, the inverter voltage square wave signal Ur and the capacitor voltage Uc pass through the zero-crossing circuit. The square wave signal is used in the phase detector to calculate the phase angle, and the phase difference θ is obtained as the input of the phase-locked loop. The phase-locked loop is implemented in the FPGA, compared with the 270° given, and an error signal is generated. After passing through the PI regulator, the control signal is output to the voltage-controlled oscillator to generate a square wave signal of the phase-locked loop output frequency. The power regulation part is completed by the DSP. The input temperature given Tref is compared with the actual temperature Ta on the load, and then Pref is output through the PI regulator. After comparison with the actual power Pa, the duty cycle is obtained after passing through the PI regulator. The duty cycle is transmitted to the FPGA through the IIC. The FPGA generates four inverter pulse drive signals with variable duty cycle and frequency based on the duty cycle and the phase-locked loop output frequency, and applies them to the inverter bridge.

[0019] Optionally, the circuit protection device is a circuit breaker.

[0020] Optionally, the visual device adopts an industrial computer.

[0021] Optionally, the staff's docking device includes at least one of a personal computer, a laptop, a smart phone, a tablet computer and a portable wearable device.

[0022] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0023] The present invention discloses an induction heating power supply control system, which includes a control unit for collecting current temperature, determining a duty cycle based on a PI regulator, and generating an inverter pulse drive signal based on the duty cycle and a phase-locked loop output frequency; the inverter pulse drive signal is used to control an inverter bridge; a heating unit connected to the control unit and configured to perform corresponding actions according to the inverter pulse drive signal to achieve induction heating power supply control; a circuit protection device connected to the control unit and a load, respectively, for performing overcurrent and overvoltage protection according to external input protection signals, and cutting off the power supply to protect the system from damage; and a visual device connected to the control unit for generating a visual chart based on the collected temperature signal, power signal, and frequency signal, and inputting the visual chart into a staff member's docking device for real-time dynamic display. The present invention can achieve precise temperature control. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 : is the LLC circuit topology diagram in this embodiment;

[0026] Figure 2 Schematic diagram of the control process in this embodiment. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] The object of the present invention is to provide an induction heating power supply control system capable of achieving precise temperature control.

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] The present invention provides an induction heating power supply control system, comprising: a control unit, a heating unit, a circuit protection device and a visual device.

[0031] A control unit is used to collect the current temperature, determine the duty cycle based on the PI regulator, and generate an inverter pulse drive signal according to the duty cycle and the phase-locked loop output frequency; the inverter pulse drive signal is used to control the inverter bridge;

[0032] a heating unit connected to the control unit and configured to perform corresponding actions according to the inverter pulse drive signal to realize induction heating power supply control;

[0033] A circuit protection device, connected to the control unit and the load, respectively, for performing overcurrent and overvoltage protection according to an external input protection signal, and cutting off the power supply to protect the system from damage;

[0034] A visual device is connected to the control unit and is used to generate a visual chart based on the collected temperature signal and power and frequency signals, and input the visual chart into the staff's docking device for real-time dynamic display.

[0035] As a specific implementation, the heating unit specifically includes: V1 thyristor, V2 thyristor, V3 thyristor, V4 thyristor, V5 thyristor, V6 thyristor, filter capacitor C ZK , inverter bridge and LLC resonant circuit; wherein, the V1 thyristor and the V4 thyristor are connected in series to form a first parallel branch, the V3 thyristor and the V6 thyristor form a second parallel branch, and the V5 thyristor and the V2 thyristor form a third parallel branch; the first parallel branch, the second parallel branch, the third parallel branch, the filter capacitor C ZK The inverter bridge is connected in parallel with the LLC resonant circuit.

[0036] As a specific implementation, the inverter bridge is composed of four IGBTs forming an H bridge.

[0037] As a specific implementation, the LLC resonant circuit specifically includes: a resonant inductor L S , resonant capacitor C L , load inductance L L and the load resistor R L ; Wherein, the resonant inductor L S One end of the resonant inductor L is connected to the current output end of the inverter bridge. S The other end of the resonant capacitor C L and the load inductance L L One end of the load inductor L L The other end of the load resistor R L One end of the resonant capacitor C L and the load resistor R L The other end of each is connected to the current input end of the inverter bridge.

[0038] As a specific implementation, the control unit specifically includes:

[0039] The temperature collection device is used to collect the current temperature.

[0040] The control element is used for: when the three-phase AC power undergoes uncontrolled full-wave rectification to obtain a rectified voltage, after capacitor filtering to obtain a DC voltage, and then after passing through the IGBT inverter bridge to obtain an inverter voltage applied to the LLC resonant circuit, the inverter voltage square wave signal Ur and the capacitor voltage Uc pass through the square wave signal of the zero-crossing circuit to calculate the phase angle in the phase detector, and obtain the phase difference θ as the input of the phase-locked loop. The phase-locked loop is implemented in the FPGA, compared with the 270° given, and an error signal is generated. After passing through the PI regulator, the control signal is output to the voltage-controlled oscillator to generate a phase-locked loop output frequency square wave signal. The power regulation part is completed by the DSP. The input temperature given Tref is compared with the actual temperature Ta on the load, and the output Pref is passed through the PI regulator. After comparison with the actual power Pa, the duty cycle is obtained after passing through the PI regulator. The duty cycle is transmitted to the FPGA through the IIC. The FPGA generates four inverter pulse drive signals with variable duty cycle and frequency according to the duty cycle and the phase-locked loop output frequency, and applies them to the inverter bridge.

[0041] As a specific implementation, the circuit protection device is a circuit breaker, the visual device is an industrial computer, and the staff's docking device includes at least one of a personal computer, a laptop, a smart phone, a tablet computer, and a portable wearable device.

[0042] Based on the above technical solution, the following embodiments are provided.

[0043] The LLC topology has the characteristics of series and parallel LC, which can replace high-frequency step-down transformers. The traditional voltage-type LC resonant structure has a large parallel circulating current, while the LLC structure resonant circuit has a series resonant inductor L S , the resonant inductor has the function of suppressing the circulating current, and can realize the direct parallel expansion of multiple inverter bridge module units, which is especially suitable for high-power applications such as diathermy;

[0044] LLC topology is as follows Figure 1 As shown, L1, L2, and L3 are three-phase voltages, which are rectified by full-wave rectification through V1 to V6 thyristors and then filtered by capacitor C. ZK The DC voltage is obtained and then output to the inverter bridge. The inverter bridge consists of four IGBTs forming an H bridge. VT1~VT4 are connected in parallel with diodes D1~D4 respectively, and the inverter voltage Ur is output to the LLC resonant circuit. The inverter current Ir flows through the LLC circuit and the resonant capacitor C L The capacitor voltage Uc is obtained on the load resistor R L The load current I and load voltage U are obtained.

[0045] like Figure 2As shown, the three-phase AC power is rectified by uncontrolled full-wave rectification to obtain rectified voltage, filtered by capacitor to obtain DC voltage, and then passed through the IGBT inverter bridge to obtain inverter voltage applied to the LLC resonant circuit. The square wave signal of the inverter voltage Ur and the capacitor voltage Uc pass through the zero-crossing circuit to calculate the phase angle of the square wave signal (the phase of the capacitor voltage zero-crossing signal minus the phase of the inverter voltage square wave signal) in the phase detector, and the phase difference θ is obtained as the input of the phase-locked loop. The phase-locked loop is performed in the FPGA and compared with the 270° given to generate an error signal. After PI adjustment The regulator outputs a control signal to the voltage-controlled oscillator to generate a square wave signal with a phase-locked loop output frequency. The power regulation part is completed by the DSP. The input temperature is given by Tref. After comparison with the actual temperature Ta on the load, the output Pref is passed through the PI regulator. After comparison with the actual power Pa, the duty cycle is obtained after passing through the PI regulator. The duty cycle is transmitted to the FPGA through the IIC. The FPGA generates 4 inverter pulse drive signals C1~C4 with variable duty cycle and frequency according to the duty cycle and the phase-locked loop output frequency, which are applied to the inverter bridges VT1~VT4 respectively.

[0046] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0047] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. An induction heating power supply control system, characterized in that: include: A control unit is used to collect the current temperature, determine the duty cycle based on the PI regulator, and generate an inverter pulse drive signal according to the duty cycle and the phase-locked loop output frequency; The inverter pulse drive signal is used to control the inverter bridge; A heating unit connected to the control unit, configured to perform corresponding actions according to the inverter pulse drive signal to realize induction heating power supply control; A circuit protection device, connected to the control unit and the load, respectively, for performing overcurrent and overvoltage protection according to an external input protection signal, and cutting off the power supply to protect the system from damage; A visual device is connected to the control unit and is used to generate a visual chart based on the collected temperature signal and power and frequency signals, and input the visual chart into the staff's docking device for real-time dynamic display.

2. The induction heating power supply control system according to claim 1, characterized in that: The heating unit specifically includes: V1 thyristor, V2 thyristor, V3 thyristor, V4 thyristor, V5 thyristor, V6 thyristor, filter capacitor C ZK , inverter bridge and LLC resonant circuit; The V1 thyristor and the V4 thyristor are connected in series to form a first parallel branch, the V3 thyristor and the V6 thyristor form a second parallel branch, and the V5 thyristor and the V2 thyristor form a third parallel branch. The first parallel branch, the second parallel branch, the third parallel branch, and the filter capacitor C ZK The inverter bridge is connected in parallel with the LLC resonant circuit.

3. The induction heating power supply control system according to claim 2, characterized in that: The inverter bridge is composed of four IGBTs forming an H bridge.

4. The induction heating power supply control system according to claim 2, characterized in that: The LLC resonant circuit specifically includes: a resonant inductor L S , resonant capacitor C L , load inductance L L and the load resistor R L ; Wherein, the resonant inductor L S One end of the resonant inductor L is connected to the current output end of the inverter bridge. S The other end of the resonant capacitor C L and the load inductance L L One end of the load inductor L L The other end of the load resistor R L One end of the resonant capacitor C L and the load resistor R L The other end of each is connected to the current input end of the inverter bridge.

5. The induction heating power supply control system according to claim 2, characterized in that: The control unit specifically includes: A temperature collection device, used to collect current temperature; The control element is used for: when the three-phase AC power undergoes uncontrolled full-wave rectification to obtain a rectified voltage, after capacitor filtering to obtain a DC voltage, and then after passing through the IGBT inverter bridge to obtain an inverter voltage applied to the LLC resonant circuit, the inverter voltage square wave signal Ur and the capacitor voltage Uc pass through the zero-crossing circuit. The square wave signal is used in the phase detector to calculate the phase angle, and the phase difference θ is obtained as the input of the phase-locked loop. The phase-locked loop is implemented in the FPGA, compared with the 270° given, and an error signal is generated. After passing through the PI regulator, the control signal is output to the voltage-controlled oscillator to generate a square wave signal of the phase-locked loop output frequency. The power regulation part is completed by the DSP. The input temperature given Tref is compared with the actual temperature Ta on the load, and then Pref is output through the PI regulator. After comparison with the actual power Pa, the duty cycle is obtained after passing through the PI regulator. The duty cycle is transmitted to the FPGA through the IIC. The FPGA generates four inverter pulse drive signals with variable duty cycle and frequency based on the duty cycle and the phase-locked loop output frequency, and applies them to the inverter bridge.

6. The induction heating power supply control system according to claim 1, characterized in that: The circuit protection device adopts a circuit breaker.

7. The induction heating power supply control system according to claim 1, characterized in that: The visual device adopts an industrial computer.

8. The induction heating power supply control system according to claim 1, characterized in that: The staff's docking device includes at least one of a personal computer, a laptop, a smart phone, a tablet computer and a portable wearable device.

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