A control method of a multi-output inductive heating power supply

Abstract

The application discloses a control method of a multi-output induction heating power supply, and belongs to the technical field of induction heating power supplies, and comprises the following steps: S1, receiving the time-sharing sequence control instruction, and turning on an arbitrary output loop; S2, receiving the closed-loop adjustment amount of the output loop, and adjusting the on time and the pulse cycle number according to the feedback value within the start-stop time of the output loop; when the feedback value reaches a set value, the output loop stops running, after a dead time, an arbitrary output loop different from the current running loop is turned on, and the same loop cannot be turned on repeatedly in the same total adjustment cycle; and S3, circulating S2 until an end instruction is received. Through the time-sharing sequence control on the output loop, the problems of the simultaneous output of power of each coil, the electromagnetic coupling between the coils and the increased coil loss in specific occasions, such as crystal growth, epitaxy and single crystal directional solidification, which need stable and uniform temperature fields or temperature gradient temperature fields, are solved, and the control method has a good energy-saving effect.

Description

Technical Field

[0001] This invention relates to the field of induction heating power supply technology, and in particular to a control method for a multi-output induction heating power supply. Background Technology

[0002] In specific applications such as crystal growth, epitaxy, and single-crystal directional solidification, a stable and uniform temperature field or a temperature gradient is required. This is often achieved using dual-coil heating. However, the mutual inductance between the two coils makes phase-locking difficult. Currently, methods such as synchronous inverter voltage and current at the same frequency and phase, or LLC series-parallel resonance, are used to ensure normal power supply operation. However, in these methods, the induced electromotive forces of the two coils wound in the same direction are opposite, leading to increased coil energy consumption. According to field measurements, at the same temperature, dual-coil heating consumes 30% to 80% more energy than single-coil heating. Research has found that enabling the two coils to output power in a time-sequential manner can meet heating requirements while simultaneously addressing the high energy consumption issue. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies where coil energy consumption increases in dual-coil or multi-coil heating applications, and to provide a control method for a multi-output induction heating power supply.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] A control method for a multi-output induction heating power supply, the multi-output induction heating power supply comprising: a control unit, a main circuit, a switching unit, and a plurality of output circuits, wherein the main circuit and the output circuits are both electrically connected to the control unit, and the main circuit is electrically connected to the output circuits via the switching unit;

[0006] The control unit is used to output a drive signal and track the resonant frequency of the output circuit in real time, and to isolate and amplify the drive signal output by the control unit before outputting it; adjust the turn-on time and pulse cycle number of the corresponding output circuit according to the feedback value; control the switching unit to turn on and off according to the output time-sequence control command, and perform time-sequence switching on the output circuit.

[0007] The control method for the multi-output induction heating power supply includes the following steps:

[0008] S1: Upon receiving the time-sequence control command, activate any one of the output loops;

[0009] S2: Upon receiving the closed-loop regulation amount of the output circuit, during the start-stop time of the output circuit, adjust the turn-on time and pulse cycle number of the output circuit according to the feedback value. When the feedback value reaches the set value, the output circuit stops running. After the dead time, any output circuit different from the current operation is turned on, and the same circuit cannot be turned on repeatedly within the same total adjustment cycle.

[0010] S3: Repeat S2 until an end command is received.

[0011] By adopting the above technical solution and performing time-sequence control on the output circuit, the problem of electromagnetic coupling between coils, which increases coil losses, is solved in specific situations such as crystal growth, epitaxy, and single crystal directional solidification, where a stable and uniform temperature field or a temperature gradient temperature field is required. It also has a good energy-saving effect.

[0012] As a preferred embodiment of the present invention, the time-sequential control instruction is: controlling the output circuit to perform time-sequential output, setting a total adjustment cycle, the total adjustment cycle including the start-stop time and dead time of several output circuits, the start-stop time including the turn-on time and the turn-off time, and the calculation formula for the start-stop time is:

[0013]

[0014] Among them, T n T is the start / stop time of the nth output loop. 总 The total regulation period is n, m is the number of output loops, n≤m, m≥2; P n P is the rated output power of the nth output circuit. m T is the rated output power of the m-th output circuit. 死区 When it is a dead zone.

[0015] As a preferred embodiment of the present invention, the activation time is T. i T i ≤T n , among which, T n Let be the start / stop time of the nth output loop.

[0016] As a preferred embodiment of the present invention, the activation sequence of the plurality of output circuits is sequential.

[0017] As a preferred embodiment of the present invention, the control unit performs closed-loop control through a DSP (Digital Signal Processor), the DSP transmits the closed-loop adjustment amount to the FPGA, and the FPGA performs driving and phase-locked control according to the closed-loop adjustment amount.

[0018] As a preferred embodiment of the present invention, the main circuit includes an AC / DC conversion unit and an inverter unit that are electrically connected in sequence;

[0019] The AC / DC conversion unit is used to convert AC to DC.

[0020] The inverter unit is used to invert the DC to AC.

[0021] In a preferred embodiment of the present invention, the switching unit includes a plurality of electronic switches, the number of which is consistent with the number of output circuits, and the inverter unit is connected to the output circuits via the electronic switches.

[0022] As a preferred embodiment of the present invention, the AC / DC conversion unit includes a rectifier unit and an LC filter unit connected in sequence.

[0023] As a preferred embodiment of the present invention

[0024] The output circuit includes a matching unit and an induction coil unit that are electrically connected in sequence.

[0025] The matching unit is used to match the induction coil unit to its inherent resonant frequency and simultaneously match the rated output power.

[0026] The induction coil unit includes an equivalent inductance and an equivalent resistance.

[0027] As a preferred embodiment of the present invention, the matching unit includes a transformer and a capacitor, wherein the transformer and the capacitor are connected in series or in parallel.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows: by performing time-sequence control on the output circuit, the problem of electromagnetic coupling between coils and increased coil losses is solved in specific situations such as crystal growth, epitaxy, and single crystal directional solidification, where a stable and uniform temperature field or a temperature gradient temperature field is required. This results in better energy-saving effect. Attached Figure Description

[0029] Figure 1 This is a structural block diagram of a multi-output heating power supply, which is a control method for a multi-output induction heating power supply according to Embodiment 1 of the present invention.

[0030] Figure 2 This is a flowchart of a control method for a multi-output induction heating power supply according to Embodiment 1 of the present invention;

[0031] Figure 3 This is a control timing diagram of a control method for a multi-output induction heating power supply according to Embodiment 1 of the present invention;

[0032] Figure 4This is a structural block diagram of a control method for a multi-output induction heating power supply according to Embodiment 2 of the present invention;

[0033] Figure 5 This is a schematic diagram of a multi-output induction heating power supply as described in Embodiments 2-3 of the present invention. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to experimental examples and specific embodiments. However, this should not be construed as limiting the scope of the above-mentioned subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0035] Example 1

[0036] A control method for a multi-output induction heating power supply, such as Figure 1 As shown, the multi-output induction heating power supply includes: a control unit, a main circuit, a switching unit, and several output circuits. The main circuit and the output circuits are both electrically connected to the control unit, and the main circuit is electrically connected to the output circuits through the switching unit.

[0037] The control unit is used to output drive signals and track the resonant frequency of the output circuit in real time. It also isolates and amplifies the drive signals output by the control unit before outputting them. The control unit adjusts the on-time and pulse cycle number of the corresponding output circuit based on feedback values. It controls the switching unit's on / off state according to the output time-sequence control command, performing time-sequence switching on the output circuit. The drive signals include closed-loop regulation, drive pulses, and time-sequence control commands. The setpoints are configured according to actual conditions. The main circuit is used for current conversion.

[0038] The output circuit is used to generate an alternating electromagnetic field to heat the load.

[0039] like Figure 2 As shown, the control method for the multi-output induction heating power supply includes the following steps:

[0040] S1: Upon receiving the time-sequence control command, activate any one of the output loops;

[0041] S2: Upon receiving the closed-loop adjustment amount of the output circuit, during the start-stop time of the output circuit, adjust the turn-on time and pulse cycle number of the output circuit according to the feedback value. When the feedback value reaches the set value, the output circuit stops running. After the dead time, open any output circuit different from the current operation. The same circuit cannot be opened repeatedly within the same total adjustment cycle.

[0042] S3: Repeat S2 until an end command is received.

[0043] The time-sequential control command is as follows: control the output circuit to perform time-sequential output, set a total adjustment cycle, the total adjustment cycle includes the start-stop time and dead time of several output circuits, the start-stop time includes the turn-on time and the turn-off time, and the calculation formula for the start-stop time is:

[0044]

[0045] Among them, T n T is the start / stop time of the nth output loop. 总 The total regulation period is n, m is the number of output loops, n≤m, m≥2; P n P is the rated output power of the nth output circuit. m T is the rated output power of the m-th output circuit. 死区 This refers to the dead zone time.

[0046] The activation time is T. i T i ≤T n , among which, T n Let be the start / stop time of the nth output loop.

[0047] Dead time is related to the energy release time on the load side and also to the resonant frequency; it is generally 3 resonant cycles. Both the total adjustment cycle and dead time can be set online.

[0048] Control timing diagram as follows Figure 3 As shown, it can also quickly recover during intermittent output, ensuring stable power for each segment.

[0049] By implementing time-sequence control of the output circuit, the problem of electromagnetic coupling between coils, which increases coil losses, is solved in specific situations requiring a stable and uniform temperature field or a temperature gradient field, such as crystal growth, epitaxy, and single crystal directional solidification. This results in better energy-saving performance. At the same time, a dead time is set to ensure that the energy on the load side can be completely released, achieving zero mutual electromagnetic coupling.

[0050] Example 2

[0051] The difference between this embodiment and Embodiment 1 is that;

[0052] The control unit performs closed-loop control through a DSP, which transmits the closed-loop adjustment to the FPGA. The FPGA then performs driving and phase-locked control based on the driving signal.

[0053] Specifically, the control unit is composed of core components such as DSP and FPGA, which realizes constant power and constant current closed-loop control, synchronous signal processing, controls the drive pulse of the inverter unit, and controls the switching switch.

[0054] like Figure 5 As shown, the main circuit includes an AC / DC conversion unit and an inverter unit that are electrically connected in sequence;

[0055] The AC / DC conversion unit is used to convert AC to DC.

[0056] The inverter unit is used to invert the DC to AC.

[0057] The switching unit includes a number of electronic switches, the number of which is consistent with the number of output circuits, and the inverter unit is connected to the output circuits via the electronic switches.

[0058] The AC / DC conversion unit includes a rectifier unit and an LC filter unit that are connected in sequence.

[0059] Specifically, such as Figure 5 As shown, the LC filter unit includes an inductor L1 and a capacitor C1. The first port of the inductor L1 is electrically connected to the first port of the rectifier unit, the second port of the inductor L1 is electrically connected to the first port of the capacitor C1, and the second port of the capacitor C1 is electrically connected to the second port of the rectifier unit.

[0060] like Figure 4 As shown, the output circuit includes a matching unit and an induction coil unit connected in sequence, and also includes a synchronization unit and a data acquisition unit connected thereto.

[0061] The synchronization unit is a current transformer, used to feed back the inverter current output by the inverter unit to the control unit, and to track the LC resonant frequency formed by the matching unit and the induction coil unit in real time.

[0062] The acquisition unit is used to acquire the voltage signal and current signal of the induction coil unit. The voltage signal and the current signal are fed back to the control unit as feedback values. The control unit drives the switching unit to switch the on and off of the output circuit according to the time-sequence control command.

[0063] The matching unit is used to match the induction coil unit to its inherent resonant frequency and simultaneously match its rated output power.

[0064] Specifically, since the resonant frequency of induction heating shifts with the temperature of the load, simple fixed-frequency alternating operation cannot achieve good output power matching. The acquisition unit collects the feedback closed-loop regulation, realizing power closed-loop, and the synchronization signal fed back by the synchronization unit realizes phase locking. Therefore, energy saving and load matching are achieved.

[0065] like Figure 5 As shown, the matching unit includes a transformer and a capacitor, wherein the transformer and the capacitor are connected in series or in parallel;

[0066] The induction coil unit includes an equivalent inductance and an equivalent resistance.

[0067] Example 3

[0068] This embodiment is a specific implementation of embodiment 2;

[0069] like Figure 5 As shown, the inverter unit uses one H-bridge to achieve two inverter outputs, or two outputs simultaneously.

[0070] For example, the switching unit consists of electronic switch S1 and electronic switch S2, which switch the output circuit according to the time-sequence control command.

[0071] The synchronization unit consists of current transformers CT1 and CT2. It collects the inverter current and feeds it back to the control unit. It tracks the LC resonant frequency formed by the matching unit and the induction coil unit in real time, so that the power output frequency is consistent with its system's natural frequency, ensuring that the inverter unit operates in a soft-switching state and achieving energy saving.

[0072] Specifically, the output timing control command is to make coil 1 run. The control unit sends a drive signal to close electronic switch S1 and open electronic switch S2. During the start-stop time of coil 1, the synchronization unit feeds back a frequency synchronization signal to the control unit for phase locking. The acquisition unit collects voltage and current as feedback quantities and feeds them back to the control unit for closed-loop regulation. After receiving the feedback quantity from coil 1, the turn-on time is adjusted to T according to the feedback value. i T i ≤T n The number of pulse cycles for the control output is i, where i*T≤T n T is the resonant period of the nth output; the coil 1 is made to run according to the number of output pulse cycles. When the feedback value reaches the set value, the coil 1 stops running. After the dead time, the control unit sends a drive signal to drive the electronic switch S1 to open and the electronic switch S2 to close, so that the coil 2 runs; the cycle is repeated.

[0073] Example 4

[0074] The difference between this embodiment and embodiment 3 is that;

[0075] The system includes three output circuits. When these three circuits are randomly activated, a time-sequential control command is output, causing coil 1 to operate randomly. The control unit sends a drive signal to close electronic switch S1 and open electronic switches S2 and S3. During the start-stop time of coil 1, the synchronization unit feeds back a frequency synchronization signal to the control unit for phase locking. The acquisition unit collects voltage and current as feedback values ​​and feeds them back to the control unit for closed-loop regulation. Upon receiving the feedback value from coil 1, the control unit adjusts the activation time to T based on the feedback value. i The number of pulse cycles for the control output is i. When the feedback value reaches the set value, coil 1 stops running. After the dead time, the control unit sends a drive signal to drive electronic switch S1 to open and electronic switch S2 or electronic switch S3 to close, so that the corresponding coil runs. The operation is cycled in sequence.

[0076] Example 5

[0077] The difference between this embodiment and embodiment 3 is that;

[0078] When the three output circuits are turned on sequentially, the output timing control command causes coil 1 to run. The control unit sends a drive signal to close electronic switch S1 and open electronic switches S2 and S3. During the start-stop time of coil 1, the synchronization unit feeds back a frequency synchronization signal to the control unit for phase locking. The acquisition unit collects voltage and current as feedback values ​​and sends them to the control unit for closed-loop regulation. Upon receiving the feedback value from coil 1, the control unit adjusts the turn-on time to T based on the feedback value. i The number of pulse cycles for the control output is i. When the feedback value reaches the set value, coil 1 stops running. After the dead time, the control unit sends a drive signal to drive electronic switch S1 to open and electronic switch S2 to close, so that coil 2 runs. This cycle is repeated.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A control method for a multi-output induction heating power supply, wherein the multi-output induction heating power supply comprises: A control unit, a main circuit, a switching unit, and several output circuits, characterized in that the main circuit and the output circuits are both electrically connected to the control unit, and the main circuit is electrically connected to the output circuits via the switching unit; The control unit is used to output isolated and amplified drive signals, and to track the resonant frequency of the output circuit in real time; to control the switching unit to turn on and off according to the output time-sequence control command, and to switch the output circuit in a time-sequence manner; and to adjust the turn-on time and pulse cycle number of the corresponding output circuit according to the feedback value. The control method for the multi-output induction heating power supply includes the following steps: S1: Upon receiving the time-sequence control command, activate any one of the output loops; S2: Upon receiving the closed-loop regulation amount of the output circuit, during the start-stop time of the output circuit, adjust the turn-on time and pulse cycle number of the output circuit according to the feedback value. When the feedback value reaches the set value, the output circuit stops running. After the dead time, any output circuit different from the current operation is turned on, and the same circuit cannot be turned on repeatedly within the same total adjustment cycle. S3: Repeat S2 until an end command is received; The time-sequential control command is as follows: control the output circuit to perform time-sequential output, set a total adjustment cycle, the total adjustment cycle includes the start-stop time and dead time of several output circuits, the start-stop time includes the turn-on time and the turn-off time, and the calculation formula for the start-stop time is: ， in, Let be the start / stop time of the nth output loop. The total adjustment period is n, m is the number of output loops, n≤m, m≥2; The rated output power of the nth output circuit. The rated output power of the m-th output circuit is... This refers to the dead zone time.

2. The control method for a multi-output induction heating power supply according to claim 1, characterized in that, The opening time is T i , T i ≤ T n ,in, Let be the start / stop time of the nth output loop.

3. The control method for a multi-output induction heating power supply according to claim 1, characterized in that, The output circuits are turned on sequentially.

4. The control method for a multi-output induction heating power supply according to claim 1, characterized in that, The control unit performs closed-loop control through a DSP. The DSP transmits the closed-loop adjustment amount to the FPGA, and the FPGA performs driving and phase-locked control based on the closed-loop adjustment amount.

5. The control method for a multi-output induction heating power supply according to claim 1, characterized in that, The main circuit includes an AC / DC conversion unit and an inverter unit that are electrically connected in sequence. The AC / DC conversion unit is used to convert AC to DC. The inverter unit is used to invert the DC to AC.

6. The control method for a multi-output induction heating power supply according to claim 5, characterized in that, The switching unit includes a number of electronic switches, the number of which is consistent with the number of output circuits, and the inverter unit is connected to the output circuits via the electronic switches.

7. The control method for a multi-output induction heating power supply according to claim 5, characterized in that, The AC / DC conversion unit includes a rectifier unit and an LC filter unit that are connected in sequence.

8. The control method for a multi-output induction heating power supply according to claim 5, characterized in that, The output circuit includes a matching unit and an induction coil unit that are electrically connected in sequence. The matching unit is used to match the induction coil unit to its inherent resonant frequency and simultaneously match the rated output power. The induction coil unit includes an equivalent inductance and an equivalent resistance.

9. The control method for a multi-output induction heating power supply according to claim 8, characterized in that, The matching unit includes a transformer and a capacitor, wherein the transformer and the capacitor are connected in series or in parallel.

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