Analysis of Common Defects of IGBT Induction Heating Power Supply

At present, most domestic manufacturers have adopted the induction heating power supply of IGBT structure. The heating power supply of this structure can maintain long-term efficient operation and has high safety, so it is more popular among manufacturers and consumers.however. Although domestic IGBTs have been used to replace thyristors and tubes, great progress has been made. However, there are still some common problems and defects in the induction heating power supply equipment developed by most manufacturers.

In the process of practical application, the defects and problems of common domestic IGBT heating power supply are mainly as follows:

Reduced work efficiency, large consumption of electric energy and cooling water after long-term application;

The power component IGBT is very susceptible to damage;

Reactor or output transformer is easily damaged;

The cooling water circuit is prone to failure;

The heating power supply has a low power factor and a large harmonic pollution;

The equipment has reliable and continuous running performance.

The above problems occur in the course of operation, and the main reason is that there are defects in the design. Now we will further explore the reasons for these problems. The first is the problem of large consumption of electric energy and cooling water. Since the IGBT, reactor, output transformer and resonant capacitor are all water-cooled, not only the loss is large, the efficiency is low, the cooling water consumption is large, and it is easy to occur because of copper tube scaling. Blockage causes the device to burn out, and it is also prone to problems such as water leakage and widening of the fault range (contacting the solution provided by the company). And because there are many parallel branches in the waterway, the system cannot guarantee that each branch has the function of water cut protection.

The IGBT power component is prone to damage, because the analog control circuit can not adapt to various changing conditions, so that the power component IGBT is out of the zero-cross soft-switching state, so the switching loss increases and the power component IGBT isdamaged. The pulse width modulation type (chopperless voltage regulation) uses a soft-on, hard-off or buffered hard-off circuit, so the IGBT loss is large, and this method is easy to break away from the soft-switching state and cause IGBT damage.

During operation of the IGBT heating power, the output transformer and a reactor are very susceptible to damage. The reason for the failure or damage of the two is due to the fact that the control circuit cannot effectively limit and protect the device under the conditions of overvoltage, overload, short circuit or partial short circuit of the induction coil, overheating of the power component, etc. Under such conditions, the reactance is easily caused. The output transformer or output transformer is susceptible to damage. A device with parallel resonance mode is prone to overvoltage of the inverter unit and damage the device. After rectification, large-capacity power capacitor filtering is adopted directly, and there is no filter inductor or DC side IGBT chopper circuit, so the power factor is low and the input current harmonic is large.

The above is the shortcomings and brief analysis of the IGBT -type induction heating power supply used in China . It is hoped that it will help engineers to complete the system design and avoid design defects in the process of R&D.