Temperature Uniformity Control in Microwave Heating Systems via High-Voltage Power Supply Regulation

Microwave heating is widely used in industrial processing (e.g., food sterilization, material drying) and household appliances due to its fast heating rate. However, uneven microwave field distribution, often caused by unstable output power of the high-voltage power supply driving the magnetron, leads to significant temperature variations (up to ±15°C) in the heated material. This not only affects product quality (e.g., overcooking or undercooking of food) but also reduces energy efficiency.
To improve temperature uniformity, a dynamic power regulation strategy for the microwave heating system’s high-voltage power supply is developed. First, a power feedback loop is established using a high-speed power sensor that measures the magnetron’s output power every 1 ms. The power supply adjusts its output voltage (ranging from 3 kV to 5 kV) based on the feedback signal to maintain the magnetron’s power stability within ±2%. Second, a spatial power distribution control algorithm is integrated. The algorithm uses temperature data from a 16-point infrared temperature sensor array placed in the heating chamber to identify hotspots and cold spots. It then adjusts the power supply’s pulse duty cycle (from 30% to 70%) in different regions of the microwave field by controlling multiple magnetrons (in multi-magnetron systems) or a rotating mode stirrer (in single-magnetron systems). For example, if a hotspot is detected at 80°C (target temperature: 65°C), the power supply reduces the duty cycle for the corresponding magnetron by 20% to lower the local power density.
Experimental tests on a 2.45 GHz microwave oven show that the optimized power supply reduces the temperature variation in a 1 kg batch of food from ±12°C to ±3°C. The energy efficiency of the heating system is improved by 18% due to reduced power waste in overheated regions. This control strategy not only enhances product quality but also makes microwave heating more suitable for industrial applications requiring precise temperature control, such as the production of pharmaceutical intermediates.