Abstract: This paper introduces a discharge system that employs IGBT power devices, PWM control, and Constantan resistance alloy as the discharge resistor. The discharge current can be continuously adjusted within a wide range of 4 to 20A, offering high constant current precision. It is designed for checking the load capacity and capacity of large-capacity batteries. The results demonstrate that the development of this system has significantly improved the precision and reliability of battery monitoring equipment.
Keywords: IGBT, PWM discharge system
As a critical backup power source, the battery plays an indispensable role in the DC system and is widely utilized across industries such as power, telecommunications, finance, and transportation. Typically, the battery pack remains in a floating charge standby mode, with the load being powered by AC sources. However, when the AC power fails, the battery pack takes over and provides energy to the load. To ensure the battery pack's actual capacity and the system's stable operation, it is standard practice to conduct a verification discharge test annually. Currently, most discharge devices on the domestic market rely on variable resistors, resistance plates, or carbon rods, requiring manual adjustments to the discharge current. These methods suffer from low control precision and cumbersome operations. In response to these limitations, our team has developed an automatic constant current discharge system. This system incorporates advanced IGBT high-power electronic components, PWM pulse-width modulation control technology, and Constantan resistance alloy as the discharge resistor. The discharge current can be continuously adjusted within a wide range while maintaining high constant current precision. The high-power electronic load and constant current control technology enable the system to handle inrush currents of up to 100A and maintain a long-term constant current load of 20A, facilitating effective battery load capacity detection and capacity verification.
The key technical specifications are detailed in Table 1 below:
| Specifications | HL-48 | HL-110 | HL-220 |
|---|---|---|---|
| Use Voltage/V | 40~60 | 90~145 | 180~275 |
| Discharge Current/A | 4~40 | 4~20 | 4~15 |
| Constant Current Accuracy | 1% | 1% | 1% |
| Voltage Accuracy (%) | 0.5% (with smart battery monitoring system) | 0.5% | 0.5% |
| Size/mm | 540 × 400 × 130 | 540 × 400 × 130 | 540 × 400 × 130 |
| Weight/kg | 8.5 | 8.5 | 8.5 |
1. Discharge System Operation
The discharge system comprises three main parts: the IGBT power device section, the PWM integrated drive circuit section, and the sampling, amplification, comparison, and feedback section. The system block diagram is illustrated in Figure 1 below:
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