A method for automatic shutdown and quick wake-up of an induction heating power supply under no-load and light-load conditions
By monitoring the active power and current phase difference of the resonant circuit in real time, the induction heating power supply can be automatically shut down and quickly woke up under no-load and light-load conditions. This solves the problems of energy waste and equipment damage in traditional induction heating power supplies under no-load or light-load conditions, and realizes automated energy saving and efficient production.
Patent Information
- Application Number
- CN202611132682.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-29
- Publication Date
- 2026-11-03
AI Technical Summary
Traditional induction heating power supplies cannot automatically shut down when unloaded or lightly loaded, resulting in wasted energy and equipment damage. Furthermore, the restart process relies on manual operation, making it impossible to achieve automated continuous production.
By monitoring the active power and voltage-current phase difference of the resonant circuit in real time, load status identification is achieved using a dual-parameter joint criterion. The system automatically shuts down when under no-load or light-load conditions, adopts an intermittent probe pulse mode during standby, and resumes full power output when quickly woken up.
It achieves high-precision and high-reliability load status identification, avoids energy waste and equipment damage, automates the power start-up and shutdown process, and improves equipment safety and production efficiency.
Smart Images
Figure CN123035573A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of induction heating power supply control technology, specifically a method for automatic shutdown and rapid wake-up of an induction heating power supply under no-load and light-load conditions. Background Technology
[0002] Induction heating power supplies are widely used in industrial fields such as metal heat treatment, smelting and welding. Traditional equipment usually maintains standby operation when the workpiece is not placed, or directly cuts off the power after detecting no load, relying on manual intervention to restart in order to maintain the basic state and responsiveness of the system.
[0003] Existing load status detection methods involve setting a fixed delay time (e.g., 30 seconds to 5 minutes). When no load or light load is detected, the output is cut off after the delay. This method easily leads to continuous no-load heating of the coil during the delay period, wasting electrical energy. Furthermore, the coil may suffer insulation damage due to no-load overheating. Restarting requires manual operation or waiting for a long re-oscillation establishment time, or the operator can manually start and stop the power supply based on experience. However, this method relies on manual judgment, resulting in untimely response; the operator's workload is high; and it cannot achieve automated continuous production, failing to meet the working requirements of induction heating power supply control. Therefore, a method for automatic shutdown and rapid wake-up of induction heating power supply under no-load and light load conditions is proposed. Summary of the Invention
[0004] To address the shortcomings of existing technologies, this invention provides a method for automatic shutdown and rapid wake-up of an induction heating power supply under no-load and light-load conditions, thereby solving the aforementioned technical problems.
[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for automatic shutdown and rapid wake-up of an induction heating power supply under no-load and light-load conditions, comprising the following steps: S1 monitors the resonant circuit status parameters in real time: First, the main control unit is used to collect the voltage U and current I signals of the resonant circuit in real time through voltage transformers and current transformers, and the active power of the resonant circuit is calculated simultaneously. Phase difference between voltage and current Among them, active power ; The phase difference is calculated by measuring the time difference between the zero-crossing of voltage and current using the zero-crossing detection method. ; S2 load status determination: Preset active power threshold and phase difference threshold The active power obtained in step S1 is then... Preset active power threshold Compare and divide the phase difference With respect to the preset phase difference threshold Compare; When satisfied or When the condition is met, the resonant circuit is determined to be in an unloaded or lightly loaded state. S3: Automatic shutdown After the main control unit determines that the inverter is in an unloaded or lightly loaded state according to step S2, it immediately blocks the inverter's drive pulse to cut off the power output. S4 detection pulse mode: After completing the shutdown in step S3, it enters a low-power standby state and operates at a fixed detection cycle. A width of [value] is intermittently applied to the resonant circuit. A short-duration detection pulse with an amplitude lower than the rated output voltage; S5 Quick Wake-Up: During step S4, the equivalent impedance Z of the resonant circuit and the active power during the detection period are monitored in real time. or phase difference during detection ; When the monitored equivalent impedance Z satisfies Or the active power during the detection period Greater than or the phase difference during the detection period Less than When any of the conditions in the above conditions are met, it is determined that the load has been restored, and then it immediately returns to the full power output mode.
[0006] Preferably, in step S1, the formula for calculating active power includes... This represents the total number of sampling points within the sampling window. For sampling sequence number, For the first The instantaneous voltage value of the resonant circuit corresponding to each sampling point For the first The instantaneous current value of the resonant circuit corresponding to each sampling point, and in the formula for calculating the phase difference, The phase difference between voltage and current. The operating frequency of the resonant circuit. It is the time difference between the voltage zero-crossing point and the current zero-crossing point. Pi is the mathematical constant of a circle.
[0007] Preferably, in step S2, the active power threshold is... The phase difference threshold is set to 5% to 15% of the rated active power of the induction heating power supply. The two discrimination thresholds are set to 150% to 200% of the phase difference under rated load conditions. This setting is related to the rated operating conditions of the equipment and can be adapted to induction heating equipment of different power levels. It fits the actual load characteristics and improves the adaptability and accuracy of no-load and light-load condition judgment.
[0008] Preferably, the load status determination in step S2 is completed within a preset determination window time, which is 5 milliseconds to 20 milliseconds. Completing the load status determination within the preset determination window can effectively filter out instantaneous electrical interference and operating condition fluctuations, avoid misjudgment and shutdown, and improve the stability and operational reliability of load status identification.
[0009] Preferably, in step S3, while cutting off the power output, the system also records and stores the operating parameters before shutdown in a register. The operating parameters include at least the resonant frequency and the power setting value. Recording the core operating parameters and storing them in the register at the time of shutdown can provide a reference for subsequent rapid wake-up, eliminating the parameter recalibration step in the restart phase and effectively shortening the response time for load recovery.
[0010] Preferably, in step S4, the width of the detection pulse... The detection period is 1 to 5 milliseconds, with a pulse amplitude of 30% to 50% of the rated output voltage. The pulse width, amplitude, and transmission period can be configured from 0.3 seconds to 1.0 seconds, which can minimize standby power consumption while ensuring load detection sensitivity, thus balancing energy saving and detection response performance.
[0011] Preferably, in step S5, the fast wake-up further includes: when it is determined that the load has recovered, immediately stop sending probe pulses, and read the resonant frequency recorded before the shutdown from the register, and use this as the initial value to start the phase-locked loop to quickly track the current resonant frequency. Using the resonant frequency recorded before the shutdown as the initial tracking value of the phase-locked loop can significantly reduce the frequency locking time, accelerate the recovery speed of full power output, and achieve a smooth and fast start-up after the load has recovered.
[0012] Preferably, in step S5, the preset wake-up condition further includes a power recovery criterion. Phase recovery criterion When any one of the three criteria is met, it is determined that the workpiece has been returned and the load has been restored. The three wake-up criteria of impedance, power and phase complement each other, which can capture load change characteristics from multiple dimensions, improve the sensitivity and comprehensiveness of load recovery detection, and avoid missed detection and delay in wake-up time.
[0013] Compared with the prior art, the present invention provides a method for automatic shutdown and rapid wake-up of an induction heating power supply under no-load and light-load conditions, which has the following beneficial effects: The automatic shutdown and rapid wake-up method for no-load and light-load conditions of this induction heating power supply achieves high-precision and high-reliability identification of load status by real-time monitoring of the active power and voltage-current phase difference of the resonant circuit and using a dual-parameter joint criterion. This effectively avoids malfunctions caused by interference with a single parameter. At the same time, when the system is determined to be in an no-load or light-load state, it immediately executes automatic shutdown, completely cutting off power output and eliminating energy waste at the source. It also effectively reduces the electrical and thermal stress on the power devices and induction coils, thereby improving the safety and service life of the equipment. During standby, the system switches to an extremely low-power intermittent probe pulse mode instead of continuous operation or complete power-off. This eliminates the reliance on manual operation and lengthy restart waits of traditional solutions, making the power supply start-up and shutdown process fully automated. This perfectly matches the high-efficiency, highly automated continuous industrial production rhythm, and comprehensively achieves the goals of energy saving, equipment protection, and production efficiency improvement. Attached Figure Description
[0014] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation
[0015] Please see Figure 1 This invention provides a technical solution: a method for automatic shutdown and rapid wake-up of an induction heating power supply under no-load and light-load conditions, comprising the following steps: S1 monitors the resonant circuit status parameters in real time: First, the main control unit is used to collect the voltage U and current I signals of the resonant circuit in real time through voltage transformers and current transformers, and the active power of the resonant circuit is calculated simultaneously. Phase difference between voltage and current Among them, active power ; The phase difference is calculated by measuring the time difference between the zero-crossing of voltage and current using the zero-crossing detection method. ; In the formula for calculating active power This represents the total number of sampling points within the sampling window. For sampling sequence number, For the first The instantaneous voltage value of the resonant circuit corresponding to each sampling point For the first The instantaneous current value of the resonant circuit corresponding to each sampling point, and in the formula for calculating the phase difference, The phase difference between voltage and current. The operating frequency of the resonant circuit. It is the time difference between the voltage zero-crossing point and the current zero-crossing point. Pi; In practical implementation, the analog voltage and current signals acquired by the transformer are first filtered, denoised, and amplitude adapted by the signal conditioning circuit before being transmitted to the analog-to-digital conversion port of the main control unit. The two sampling channels employ a synchronous triggering mechanism to ensure consistent time references at each sampling point, avoiding deviations in phase calculation. During zero-crossing detection, the sinusoidal voltage and current signals are first converted into square wave signals of the same frequency. The acquisition peripherals of the main control unit record the time difference between the zero-crossing points of the two signals, which is then calculated to obtain the zero-crossing time difference. Active power is calculated iteratively using a sliding sampling window to ensure the real-time and continuous nature of the monitoring results. S2 load status determination: Preset active power threshold and phase difference threshold The active power obtained in step S1 is then... Compared with the preset active power threshold Compare and divide the phase difference With respect to the preset phase difference threshold Compare; When satisfied or When the conditions are met, the resonant circuit is determined to be in an unloaded or lightly loaded state, and the active power threshold is... The phase difference threshold is set to 5% to 15% of the rated active power of the induction heating power supply. Set to 150% to 200% of the phase difference under rated load conditions; Furthermore, the load status is determined within a preset judgment window time, which ranges from 5 milliseconds to 20 milliseconds. The active power threshold and phase difference threshold are calibrated during the equipment factory commissioning stage. They are determined by averaging multiple samples under no-load and rated load conditions, respectively. Multiple sets of threshold parameters can be preset for use according to different workpiece specifications and coil parameters. The judgment window adopts a continuous sampling and counting mechanism. The final state judgment result is only output when all sampling cycles within the window meet the no-load or light-load judgment conditions, so as to suppress misjudgment caused by instantaneous power grid fluctuations and signal interference. S3: Automatic shutdown After the main control unit determines that the inverter is in an unloaded or lightly loaded state according to step S2, it immediately blocks the inverter's drive pulse to cut off the power output. While cutting off the power output, it also includes synchronously recording the operating parameters before shutdown and storing them in a register. The operating parameters include at least the resonant frequency and the power setting value. When the inverter drive pulse is blocked, the main control unit forces the PWM output port to an invalid level, and at the same time triggers the optocoupler-isolated hardware interlock circuit to cut off the drive power supply of the inverter bridge, forming a double shutdown protection; the recorded operating parameters also include the current phase compensation value and the phase-locked loop configuration parameters, all of which are stored in a non-volatile register to ensure that the parameters can still be retained after the device is powered off, and can be directly retrieved without recalibration when the device is woken up; S4 detection pulse mode: After completing the shutdown in step S3, it enters a low-power standby state and operates at a fixed detection cycle. Intermittently apply a width of [value] to the resonant circuit A short-duration detection pulse with an amplitude lower than the rated output voltage; And the width of the detection pulse The pulse duration is 1 to 5 milliseconds, the pulse amplitude is 30% to 50% of the rated output voltage, and the detection period is... The short-time detection pulse is 0.3 to 1.0 seconds. The main control unit generates a narrow-width PWM sequence, which is then converted by the inverter power unit and applied to the resonant circuit. The pulse output frequency is swept in a small range around the resonant frequency recorded before shutdown to ensure that the circuit is in a weak resonance state to improve detection sensitivity. The signal sampling circuit is only turned on during the pulse output phase in each detection cycle, and the power drive and redundant sampling channels are turned off during other periods to further reduce standby power consumption. S5 Quick Wake-Up: During step S4, the equivalent impedance Z of the resonant circuit and the active power during the detection period are monitored in real time. or phase difference during detection ; When the monitored equivalent impedance Z satisfies or active power during detection Greater than or phase difference during detection Less than If any of the conditions in the above conditions are met, it is determined that the load has been restored, and the system immediately returns to full power output mode. The rapid wake-up further includes: when the load is determined to be restored, immediately stop sending probe pulses and read the resonant frequency recorded before the shutdown from the register, and use this as the initial value to start the phase-locked loop to quickly track the current resonant frequency; The preset wake-up conditions also include power recovery criteria. Phase recovery criterion When any one of the three criteria is met, it is determined that the workpiece has been returned and the load has been restored. By real-time monitoring of the active power and voltage-current phase difference of the resonant circuit and using dual-parameter joint criteria, high-precision and high-reliability identification of the load status is achieved, effectively avoiding malfunctions caused by interference with a single parameter. At the same time, when the system is judged to be in an unloaded or light-load state, it immediately performs automatic shutdown, completely cutting off power output, eliminating energy waste at the source, and effectively reducing the electrical and thermal stress on power devices and induction coils, thereby improving the safety and service life of the equipment. During standby, the system switches to an extremely low-power intermittent probe pulse mode instead of continuous operation or complete power-off. This eliminates the reliance on manual operation and lengthy restart waits of traditional solutions, making the power supply start-up and shutdown process fully automated. This perfectly matches the high-efficiency, highly automated continuous industrial production rhythm, and comprehensively achieves the goals of energy saving, equipment protection, and production efficiency improvement.
[0016] This solution achieves high-precision and high-reliability identification of load status by real-time monitoring of the active power and voltage-current phase difference of the resonant circuit and using a dual-parameter joint criterion. It effectively avoids malfunctions caused by interference with a single parameter. At the same time, when the system is judged to be in an unloaded or light-load state, it immediately performs automatic shutdown, completely cutting off power output, eliminating energy waste at the source, and effectively reducing the electrical and thermal stress on power devices and induction coils, thereby improving the safety and service life of the equipment. During standby, the system switches to an extremely low-power intermittent probe pulse mode instead of continuous operation or complete power-off. This eliminates the reliance on manual operation and lengthy restart waits of traditional solutions, making the power supply start-up and shutdown process fully automated. This perfectly matches the high-efficiency, highly automated continuous industrial production rhythm, and comprehensively achieves the goals of energy saving, equipment protection, and production efficiency improvement.
Claims
1. A method for automatic shutdown and rapid wake-up of an induction heating power supply under no-load and light-load conditions, characterized in that, Includes the following steps: S1 monitors the resonant circuit status parameters in real time: First, the main control unit is used to collect the voltage U and current I signals of the resonant circuit in real time through voltage transformers and current transformers, and the active power of the resonant circuit is calculated simultaneously. Phase difference between voltage and current Among them, active power ; The phase difference is calculated by measuring the time difference between the zero-crossing of voltage and current using the zero-crossing detection method. ; S2 load status determination: Preset active power threshold and phase difference threshold The active power obtained in step S1 is then... Compared with the preset active power threshold Compare and divide the phase difference With respect to the preset phase difference threshold Compare; When satisfied or When the condition is met, the resonant circuit is determined to be in an unloaded or lightly loaded state. S3 Automatic Shutdown: After the main control unit determines that the inverter is in an unloaded or lightly loaded state according to step S2, it immediately blocks the inverter's drive pulse to cut off the power output. S4 detection pulse mode: After completing the shutdown in step S3, it enters a low-power standby state and operates at a fixed detection cycle. A width of [value] is intermittently applied to the resonant circuit. A short-duration detection pulse with an amplitude lower than the rated output voltage; S5 Quick Wake-Up: During step S4, the equivalent impedance Z of the resonant circuit and the active power during the detection period are monitored in real time. or phase difference during detection ; When the monitored equivalent impedance Z satisfies Or the active power during the detection period Greater than or the phase difference during the detection period Less than When any of the conditions in the above conditions are met, it is determined that the load has been restored, and then it immediately returns to the full power output mode.
2. The method for automatic shutdown and rapid wake-up of an induction heating power supply under no-load and light-load conditions according to claim 1, characterized in that: In step S1, the formula for calculating active power is as follows: This represents the total number of sampling points within the sampling window. For sampling sequence number, For the first The instantaneous voltage value of the resonant circuit corresponding to each sampling point. For the first The instantaneous current value of the resonant circuit corresponding to each sampling point, and in the formula for calculating the phase difference, The phase difference between voltage and current. The operating frequency of the resonant circuit It is the time difference between the voltage zero-crossing point and the current zero-crossing point. Pi is the mathematical constant of a circle.
3. The method for automatic shutdown and rapid wake-up of an induction heating power supply under no-load and light-load conditions according to claim 1, characterized in that: In step S2, the active power threshold The phase difference threshold is set to 5% to 15% of the rated active power of the induction heating power supply. Set to 150% to 200% of the phase difference under rated load conditions.
4. The method for automatic shutdown and rapid wake-up of an induction heating power supply under no-load and light-load conditions according to claim 1, characterized in that: The determination of the load status in step S2 is completed within a preset judgment window time, which is 5 milliseconds to 20 milliseconds.
5. The method for automatic shutdown and rapid wake-up of an induction heating power supply under no-load and light-load conditions according to claim 1, characterized in that: In step S3, while cutting off the power output, the method also includes synchronously recording the operating parameters before shutdown and storing them in a register. The operating parameters include at least the resonant frequency and the power setting value.
6. The method for automatic shutdown and rapid wake-up of an induction heating power supply under no-load and light-load conditions according to claim 1, characterized in that: In step S4, the width of the detection pulse The detection period is 1 to 5 milliseconds, with a pulse amplitude of 30% to 50% of the rated output voltage. The duration is between 0.3 seconds and 1.0 seconds.
7. The method for automatic shutdown and rapid wake-up of an induction heating power supply under no-load and light-load conditions according to claim 1, characterized in that: In step S5, the fast wake-up further includes: when it is determined that the load has recovered, immediately stop sending probe pulses, and read the resonant frequency recorded before the shutdown from the register, and use this as the initial value to start the phase-locked loop to quickly track the current resonant frequency.
8. The method for automatic shutdown and rapid wake-up of an induction heating power supply under no-load and light-load conditions according to claim 1, characterized in that: In step S5, the preset wake-up condition also includes a power recovery criterion. Phase recovery criterion When any one of the three criteria is met, it is determined that the workpiece has been returned and the load has been restored.