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What are the principles for selecting the frequency of induction heating equipment?

2020-10-28

The selection of frequency for induction heating equipment is very important because current frequency plays a very important role. The rated current frequency and heating power are the basic parameters of induction heating equipment. What are the principles for selecting frequency for induction heating equipment? Let's take a look together.
(1) The frequency principle of induction heating equipment is that when the penetrating heating steel is heated by induction quenching, when the power supply frequency is determined, the current current Penetration depth is also determined, that is, the eddy current depth is within a certain range. In fact, due to the different requirements for the depth of the hardened layer of the workpiece, there are two heating states at a certain current depth: one is that the current Penetration depth is greater than the depth of the hardened layer. It is called penetration heating; The other is that the current Penetration depth is less than the depth of the hardened layer, which is called heat conduction heating.
From the comparison of the two heating methods, it can be seen that under mass production conditions, whether it is energy-saving, labor productivity, surface overheating, etc., penetration heating method, also known as deep heating, should be chosen. It is defined as the depth of current in the hot state of the workpiece, which is greater than the required depth of the hardened layer of the workpiece.
(2) The second principle for selecting current frequency is that the current frequency cannot be too low. When the current frequency is too low, that is, when the ratio of the Penetration depth of the current to the depth of the hardened layer is too large, it is inevitable to use very high power density. When using the sensor, the current carrying density is very high (some companies specify a value not exceeding 1200A/mm2), and even under excellent water flow cooling, the sensor is easily damaged.
(3) The third principle of current frequency selection is the high Electrical efficiency of the inductor. The Electrical efficiency of the inductor depends on the ratio of the diameter (thickness) of the component to the Penetration depth of the current in the thermal state. This value is also known as the electrical dimension.
(4) The selection of current frequency is also related to noise, oscillation system power factor, and electromagnetic force. When the current frequency increases, the electromagnetic force, vibration, and noise levels on the inductor decrease at the same power; When the current frequency increases, the system power factor decreases.