中文
含义
老板电磁灶检测到直流母线电压（VDC）过低，E7 错误代码表示整流滤波后的直流母线电压低于安全工作阈值（通常低于 180V DC）。充足的母线电压是 IGBT 逆变电路正常工作的基础：电压过低时，IGBT 需要更大的占空比才能输出额定功率，导致开关损耗剧增且加热效率严重下降。控制系统检测到欠压后主动停机，避免 IGBT 在大电流低电压的恶劣工况下损坏。
常见原因
- 市电输入电压过低（低于 170V AC），常见于用电高峰时段或离变压器较远的线路末端用户。
- 电磁灶电源线或家中供电线路过长、线径过细，线路压降过大导致灶具端电压不足。
- 整流桥堆中某只二极管开路损坏，使全桥整流变为半波整流，直流输出电压降低近一半。
- 主滤波电容开路或容量严重衰减，直流母线滤波不足导致电压纹波过大，平均电压降低。
- 电源输入端的共模扼流圈或保险管接触电阻异常增大，造成输入电压在灶具内部额外跌落。
- 电磁灶同时开启多个烹饪区全功率加热，总功率需求超过家中供电线路容量，导致电压被拉低。
自助排查
- 检查家中其他电器是否同时变暗或运行无力，如空调制冷不足、灯光偏暗等，说明家中电压普遍偏低。
- 使用万用表交流电压档测量电磁灶所接插座电压。若实测低于 170V AC，则 E7 为电网欠压引起，待电网电压恢复后故障自动消除。
- 避免在同一回路上同时运行大功率电器（如空调、烤箱、电磁灶全部开启），关闭其他大功率电器后观察 E7 是否消失。
- 检查电磁灶电源线与插座接触是否良好。插头过热或插座簧片老化松驰会导致接触电阻增大产生额外压降。
- 检查家中配电箱电磁灶回路断路器（空开）额定电流是否足够。空开容量不足（如 10A 以下）会导致供电瓶颈。
- 如果电网电压正常（220V 左右）但 E7 依然出现，则为电磁灶内部整流或滤波电路故障，需联系老板售后服务检修。
English
Meaning
The Robam induction cooktop has detected an excessively low DC bus voltage (VDC). The E7 error code indicates that the DC bus voltage after rectification and filtering has fallen below the safe operating threshold (typically below 180V DC). Sufficient bus voltage is essential for the IGBT inverter circuit: at low voltage, the IGBT requires a larger duty cycle to deliver rated power, causing sharply increased switching losses and severely degraded heating efficiency. The control system shuts down proactively to prevent IGBT damage under high-current, low-voltage operating conditions.
Common Causes
- The AC mains input voltage is too low (below 170V AC), common during peak electricity usage hours or for users at the far end of a long distribution line from the transformer.
- The cooktop’s power cord or the household wiring is too long or undersized, causing excessive voltage drop at the cooktop terminals.
- One of the diodes in the rectifier bridge has failed open, reducing the full-wave rectifier to half-wave operation and cutting the DC output voltage by nearly half.
- The main filter capacitor is open-circuited or has severely degraded capacitance, resulting in inadequate DC bus filtering, excessive voltage ripple, and reduced average voltage.
- Abnormally high contact resistance in the common-mode choke or fuse holder on the power input side causes additional voltage drop inside the cooktop.
- Multiple cooking zones are operating at full power simultaneously, with total power demand exceeding the capacity of the household supply circuit, pulling the voltage down.
Self-Check Steps
- Check whether other household appliances are also dimming or running weakly (e.g., reduced air conditioning output, dimmer lights), suggesting a general low-voltage condition.
- Use a multimeter set to AC voltage to measure the voltage at the outlet the cooktop is plugged into. If the reading is below 170V AC, E7 is caused by grid undervoltage and will clear when the mains voltage recovers.
- Avoid running other high-power appliances (air conditioner, oven, cooktop) on the same circuit simultaneously. Turn off other high-power devices and observe whether E7 clears.
- Check whether the cooktop’s power cord is making good contact with the outlet. A hot plug or worn socket contacts increase contact resistance and cause additional voltage drop.
- Check whether the circuit breaker (MCB) for the cooktop in your distribution panel has sufficient current rating. An undersized breaker (e.g., 10A or less) creates a supply bottleneck.
- If the mains voltage is normal (around 220V) but E7 still appears, there is likely a rectifier or filter circuit fault inside the cooktop. Contact Robam after-sales service for diagnosis.