High input-output power factor high skin depth inductive heating power supply

Abstract

The application provides a high input and output power factor high skin depth induction heating power supply, comprising: a power input end connected with an IGBT rectifier unit circuit, an output end of the IGBT rectifier unit connected with a DC filter unit circuit; an output end of the DC filter unit connected with an input end of an IGBT inverter unit circuit, an output end of the IGBT inverter unit connected with a transformer filter output unit circuit, the transformer filter output unit connected with a power output end circuit, the IGBT rectifier unit and the IGBT inverter unit connected with a control module through an SVPWM control circuit, and the control module connected with an upper computer signal. The application has the beneficial effects that: while being energy-efficient, the voltage, current, power, frequency, temperature and efficiency of the whole machine are closed-loop controlled; any independent control in the calibration range of the voltage, current, power, frequency, temperature and efficiency can be performed respectively; different devices can be selected according to the power in the later period, and master-slave parallel machines can be used to reduce the secondary investment of customers.

Description

Technical Field

[0001] This invention relates to the field of heating technology for metal pipes, and more specifically to a high input / output power factor and high skin depth induction heating power supply. Background Technology

[0002] Currently, induction heating technology on the market is mainly used for high-temperature rapid heating in metallurgical quenching. However, its circuit function is limited and its controllability is poor. Voltage and current cannot be controlled simultaneously. In application, the magnitude of voltage and current depends on the load size, which is passive heating. The metal resistance varies greatly with temperature, meaning that voltage and current are uncontrollable. This can cause overload during precision heating, making it impossible to guarantee the load power and thus easily causing overload of the power supply circuit itself, posing a significant safety hazard. Furthermore, it cannot meet the needs of uniform and precise heating. Utility Model Content

[0003] This invention overcomes the shortcomings of the prior art and provides a high input-output power factor and high skin depth induction heating power supply.

[0004] A high input / output power factor and high skin depth induction heating power supply includes: a power input terminal connected to an IGBT rectifier unit circuit; an output terminal of the IGBT rectifier unit connected to a DC filter unit circuit; an output terminal of the DC filter unit connected to an input terminal circuit of an IGBT inverter unit; an output terminal of the IGBT inverter unit connected to a transformer filter output unit circuit; a transformer filter output unit connected to a power output terminal circuit; the IGBT rectifier unit and the IGBT inverter unit connected to a control module via an SVPWM control circuit; and the control module connected to a host computer signal.

[0005] The control module is connected to the phase angle adjustment circuit, temperature acquisition circuit, and power factor acquisition circuit respectively. The phase angle adjustment circuit and temperature acquisition circuit are connected to the transformer filter output unit circuit respectively. The power factor acquisition circuit is connected to the downstream load circuit at the power output terminal.

[0006] A circuit breaker QA1 is provided between the power input terminal and the IGBT rectifier unit circuit. The circuit breaker QA1 is connected to the first contactor KM1 circuit. The first contactor KM1 is connected to the second contactor KM2 and the IGBT rectifier unit circuit respectively. A resistor is provided between the first contactor KM1 and the second contactor KM2. The second contactor KM2 is connected to the midpoint of the circuit of the circuit breaker QA1 and the contactor KM1 to form a pre-charging circuit.

[0007] Current transformers are installed on each phase circuit connected to the second contactor KM2 and the circuit breaker QA1.

[0008] A three-phase filter capacitor C21 is installed on the circuit connecting the first contactor KM1 and the IGBT rectifier unit.

[0009] An input reactor L1 is provided in the circuit between the three-phase filter capacitor C21 and the IGBT rectifier unit.

[0010] The transformer filter output unit includes: a filter capacitor C22 and a filter capacitor C23 connected in parallel on the circuit between the transformer T1 and the power output terminal; a sampling interface XS1 and a PCB power output voltage monitoring interface on the circuit between the transformer T1 and the power output terminal; and a current transformer CT4A on the circuit between the transformer T1 and the IGBT inverter unit.

[0011] A circuit breaker QA2 is installed on the circuit between transformer T1 and the power output terminal.

[0012] The DC filter unit is equipped with a DC voltage monitoring unit PCB1 and a DC voltage monitoring unit PCB2.

[0013] The beneficial effects of this invention are as follows: while achieving high efficiency and energy saving, it realizes closed-loop control of the voltage, current, power, frequency, temperature and efficiency of the whole machine; it can independently control any voltage, current, power, frequency, temperature and efficiency within the calibration range; different devices can be selected according to different power levels in the later stage, and master-slave parallel operation can also be performed to reduce the customer's secondary repeated investment and expand different power requirements. Attached Figure Description

[0014] Figure 1 This is a structural framework diagram of the present invention; Figure 2 This is the circuit diagram of the main power switching circuit. In the diagram: 1. Power input terminal; 2. IGBT rectifier unit; 3. DC filter unit; 4. IGBT inverter unit; 5. Power output terminal. Detailed Implementation

[0015] Example A high input / output power factor and high skin depth induction heating power supply includes: a power input terminal 1 connected to an IGBT rectifier unit 2 circuit; the output terminal of the IGBT rectifier unit 2 connected to a DC filter unit 3 circuit; the output terminal of the DC filter unit 3 connected to the input terminal of an IGBT inverter unit 4 circuit; the output terminal of the IGBT inverter unit 4 connected to a transformer filter output unit circuit; the transformer filter output unit connected to a power output terminal 5 circuit; the IGBT rectifier unit 2 and the IGBT inverter unit 4 connected to a control module via an SVPWM control circuit; and the control module connected to a host computer signal.

[0016] The control module is connected to the phase angle adjustment circuit, the temperature acquisition circuit, and the power factor acquisition circuit, respectively. The phase angle adjustment circuit and the temperature acquisition circuit are connected to the transformer filter output unit circuit, respectively. The power factor acquisition circuit is connected to the downstream load circuit of the power output terminal 5.

[0017] A circuit breaker QA1 is provided between the power input terminal 1 and the IGBT rectifier unit 2 circuit. The circuit breaker QA1 is connected to the first contactor KM1 circuit. The first contactor KM1 is connected to the second contactor KM2 and the IGBT rectifier unit 2 circuit respectively. A resistor is provided between the first contactor KM1 and the second contactor KM2. The second contactor KM2 is connected to the midpoint of the circuit breaker QA1 and the contactor KM1 circuit to form a pre-charging circuit.

[0018] Current transformers are installed on each phase circuit connected to the second contactor KM2 and the circuit breaker QA1.

[0019] A three-phase filter capacitor C21 is provided on the circuit connecting the first contactor KM1 and the IGBT rectifier unit 2.

[0020] An input reactor L1 is provided in the circuit between the three-phase filter capacitor C21 and the IGBT rectifier unit 2.

[0021] The transformer filter output unit includes: a filter capacitor C22 and a filter capacitor C23 connected in parallel on the circuit between the transformer T1 and the power output terminal 5; a sampling interface XS1 and a PCB power output voltage monitoring interface on the circuit between the transformer T1 and the power output terminal 5; and a current transformer CT4A on the circuit between the transformer T1 and the IGBT inverter unit 4.

[0022] A circuit breaker QA2 is installed on the circuit between transformer T1 and power output terminal 5.

[0023] DC filter unit 3 is equipped with DC voltage monitoring unit PCB1 and DC voltage monitoring unit PCB2 respectively.

[0024] The working principle of this utility model is as follows: Figure 1 and Figure 2 As shown.

[0025] The power input terminal 1 of this scheme includes both AC power input and generator input, which are selected by a switch. Power input terminal 1 is connected to IGBT rectifier unit 2, which converts AC power to DC power. The output terminal of IGBT rectifier unit 2 is connected to DC filter unit 3, which filters and regulates the DC power. The filtered DC power is then sent by DC filter unit 3 to IGBT inverter unit 4, which inverts the DC power into controllable AC power. The output of IGBT inverter unit 4 is connected to transformer T1 filter output unit, which adjusts the voltage and filters out harmonics before finally supplying power to the downstream load.

[0026] This solution connects to a host computer via a control module, allowing the entire circuit to be monitored by the host computer.

[0027] The SVPWM control circuit receives instructions from the control module, generates PWM signals, and controls the switching actions of IGBT rectifier unit 2 and IGBT inverter unit 4 respectively.

[0028] The phase angle adjustment circuit adjusts the phase of the inverter output according to requirements, such as grid synchronization.

[0029] The power factor acquisition circuit and temperature acquisition module monitor system parameters in real time and feed back the data to the control module for dynamic adjustment of the operating status, such as power factor correction or overheat protection.

[0030] The control module uses a host computer to control the human-machine interface to set parameters, monitor status, and trigger fault alarms.

[0031] In this embodiment, the SVPWM control circuit, phase angle adjustment circuit, temperature acquisition circuit, and power factor acquisition circuit are all implemented using a control circuit board.

[0032] This invention achieves power conversion through a two-stage rectification-inverter conversion. The core control system consists of a drive SVPWM control circuit and control module, combined with sensor feedback and a human-machine interface, to complete the full-process management of power input, power conversion, and load output.

[0033] In this embodiment, the high skin depth induction heating power supply of this utility model can be divided into two main parts: a power conversion main circuit and a control circuit.

[0034] The main power conversion circuit adopts an AC-DC-AC structure, in which the AC-DC section is an IGBT rectifier unit 2; the inverter uses IGBTs as switching elements and adopts sinusoidal pulse width modulation (SVPWM) to control the inverter, converting stable DC into pulse width modulated AC output, the fundamental frequency of which is the required power output frequency; the pulse width modulated wave output by the inverter is filtered by the output LC filter circuit to output sinusoidal AC power.

[0035] The control unit mainly consists of six units: signal generation unit, SVPWM wave generation unit, feedback control unit, display unit, logic control unit, and protection unit.

[0036] Each unit consists of a circuit function module.

[0037] The signal generation unit includes a reference frequency generation unit and a sine wave generation unit; The SVPWM wave generation unit includes a triangular wave generation unit and an SVPWM wave synthesis unit; The feedback control unit includes a voltage negative feedback unit and a current negative feedback unit; The display unit can display voltage, frequency, current, power, and power factor; The control logic unit includes a soft-start unit, a fault interrupt handling unit, and a RESET unit; The protection unit includes an overload detection unit, an overvoltage detection unit, an undervoltage detection unit, a short circuit detection and protection unit, an overheat detection unit, an overcurrent detection unit, and a phase loss detection unit.

[0038] IGBT rectifiers utilize high-frequency switching pulse width modulation current to achieve sinusoidal input current. IGBT rectifier technology can reduce input harmonic current to extremely low levels while remaining unaffected by load, overcoming the problem of filter efficiency varying with power. The filter achieves true sinusoidal input with no input current. The single input power factor of IGBT rectifier power supplies is >0.99, making them behave as approximately purely resistive loads to the power grid.

[0039] like Figure 2 As shown, the high input / output power factor and high skin depth induction heating power supply in this embodiment includes a power input terminal 1, an IGBT rectifier unit 2, a DC filter unit 3, an IGBT inverter unit 4, and a detection circuit.

[0040] In this embodiment, the input power supply adopts a three-phase four-wire system, including three phase lines (A, B, C), one neutral line N, and one protective grounding line, to provide AC power for the entire circuit.

[0041] The input power first passes through circuit breaker QA1, and then connects to first contactor KM1 and second contactor KM2; first contactor KM1 and second contactor KM2 are used to control the on and off of the circuit, realizing remote or automatic control of the circuit.

[0042] The rectifier unit consists of multiple IGBT modules, including Q1, Q2, Q6, Q5, Q4, and Q3 in this embodiment. The rectifier unit converts three-phase AC power into DC power.

[0043] The three-phase alternating current is input to the three input terminals of the rectifier unit, and after rectification, direct current is obtained at the output terminal.

[0044] DC filter unit 3 includes multiple capacitors, including C1, C2, ..., C20 in this embodiment, which are used to smooth DC power, reduce ripple, and improve the quality of DC power. The multiple capacitors are connected in parallel in the DC circuit. The capacitors are mainly used to filter out high-frequency ripple.

[0045] The IGBT inverter unit 4 consists of multiple IGBT modules, which in this embodiment are Q1 and Q2. This IGBT module is the core of the inverter circuit and is responsible for converting DC power into AC power.

[0046] IGBT modules are connected according to a specific topology, such as a three-phase bridge inverter circuit. By controlling the switching state of the IGBTs, DC to AC conversion is achieved, and the required AC power is output.

[0047] DC voltage is detected by PCB1 and PCB2, and the status of DC current is monitored in real time, providing a basis for circuit protection and control.

[0048] The power supply output voltage is monitored by connecting to the PCB via the PCB power supply output voltage monitoring interface, ensuring the stability and accuracy of the output voltage.

[0049] The detection circuit is connected to the main circuit through a sampling resistor or a voltage divider circuit. As shown in the figure, in this embodiment, the monitoring function is achieved by setting current transformers CT1, CT2, CT3 and CT4A, and the detected voltage signal is transmitted to the control unit for processing.

[0050] The inverted AC power is directly connected to the output terminal QA2 to supply the load, forming a complete power electronic conversion system.

[0051] This utility model provides a 200KW power supply circuit, realizing closed-loop control of the voltage, current, power, frequency, temperature and efficiency of the whole machine; the control circuit performs high-frequency switching pulse width modulation current on the input and output of the main circuit; and uses SVPWM chopping in conjunction with the main control strategy algorithm to make the input and output power factors close to 1.

[0052] The embodiments of the present invention have been described in detail above, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made in accordance with the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A high input / output power factor and high skin depth induction heating power supply, characterized in that, include: The power input terminal is connected to the IGBT rectifier unit circuit. The output terminal of the IGBT rectifier unit is connected to the DC filter unit circuit. The output terminal of the DC filter unit is connected to the input terminal circuit of the IGBT inverter unit. The output terminal of the IGBT inverter unit is connected to the transformer filter output unit circuit. The transformer filter output unit is connected to the power output terminal circuit. The IGBT rectifier unit and the IGBT inverter unit are connected to the control module through the SVPWM control circuit. The control module is connected to the host computer signal.

2. The high input / output power factor and high skin depth induction heating power supply according to claim 1, characterized in that: The control module is connected to the phase angle adjustment circuit, temperature acquisition circuit, and power factor acquisition circuit respectively. The phase angle adjustment circuit and temperature acquisition circuit are connected to the transformer filter output unit circuit respectively. The power factor acquisition circuit is connected to the downstream load circuit at the power output terminal.

3. The high input / output power factor and high skin depth induction heating power supply according to claim 1, characterized in that: A circuit breaker QA1 is provided between the power input terminal and the IGBT rectifier unit circuit. The circuit breaker QA1 is connected to the first contactor KM1 circuit. The first contactor KM1 is connected to the second contactor KM2 and the IGBT rectifier unit circuit respectively. A resistor is provided between the first contactor KM1 and the second contactor KM2. The second contactor KM2 is connected to the midpoint of the circuit of the circuit breaker QA1 and the contactor KM1 to form a pre-charging circuit.

4. The high input / output power factor and high skin depth induction heating power supply according to claim 3, characterized in that: Current transformers are installed on each phase circuit connected to the second contactor KM2 and the circuit breaker QA1.

5. A high input / output power factor and high skin depth induction heating power supply according to claim 3, characterized in that: A three-phase filter capacitor C21 is provided on the circuit connecting the first contactor KM1 and the IGBT rectifier unit.

6. A high input / output power factor and high skin depth induction heating power supply according to claim 5, characterized in that: An input reactor L1 is provided in the circuit between the three-phase filter capacitor C21 and the IGBT rectifier unit.

7. A high input / output power factor and high skin depth induction heating power supply according to claim 1, characterized in that, The transformer filter output unit includes: a filter capacitor C22 and a filter capacitor C23 connected in parallel on the circuit between the transformer T1 and the power output terminal; a sampling interface XS1 and a PCB power output voltage monitoring interface on the circuit between the transformer T1 and the power output terminal; and a current transformer CT4A on the circuit between the transformer T1 and the IGBT inverter unit.

8. A high input / output power factor and high skin depth induction heating power supply according to claim 7, characterized in that: A circuit breaker QA2 is installed on the circuit between transformer T1 and the power output terminal.

9. A high input / output power factor and high skin depth induction heating power supply according to claim 1, characterized in that: The DC filter unit is equipped with a DC voltage monitoring unit PCB1 and a DC voltage monitoring unit PCB2.

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