The low-temperature starting performance of a car electric wireless charging stand directly impacts its reliability in cold environments, and optimizing circuit design is the key to overcoming this low-temperature bottleneck. Under low-temperature conditions, problems such as increased battery internal resistance, increased electrolyte viscosity, and shifting semiconductor device threshold voltages can cause difficulties in starting conventional circuits. This requires the coordinated use of multiple technologies to achieve stable operation in low-temperature environments.
Supercapacitor-assisted starting technology is a key solution to addressing low-temperature input voltage drops. At -40°C, the internal resistance of traditional on-board power supplies can increase several times, causing a sudden drop in input voltage during startup. Supercapacitors maintain their high capacitance at low temperatures, and when connected in parallel, they can provide high instantaneous current to power devices, compensating for insufficient battery output capacity. For example, integrating multiple supercapacitors at the input can release stored energy during low-temperature startup, minimizing voltage drops and ensuring stable operation of the control chip. This design not only avoids energy loss caused by battery preheating but also improves the system's adaptability to extreme temperatures.
Selecting wide-temperature semiconductor devices is fundamental to optimizing low-temperature performance. Traditional silicon-based MOSFETs experience a significant increase in on-resistance at low temperatures. Gallium nitride (GaN) devices, however, offer a lower on-resistance temperature coefficient and smaller threshold voltage drift, making them more suitable for low-temperature scenarios. Replacing silicon-based devices with GaN HEMTs can significantly improve low-temperature startup success rates and enhance efficiency. Some high-end models have already adopted all-GaN power module designs, enabling direct startup at -45°C without preheating.
Adaptive soft-start control algorithms effectively mitigate circuit delays at low temperatures by dynamically adjusting startup parameters. This algorithm monitors the input voltage and battery internal resistance in real time, dynamically extending the soft-start time and adjusting the initial duty cycle. For example, when the ambient temperature sensor detects low temperatures, the microcontroller automatically optimizes the PWM parameters for a smoother startup process, preventing device damage caused by sudden voltage changes. The XMC™ microcontrollers used in some models feature a built-in low-temperature compensation module that adjusts control strategies in real time based on temperature data, significantly reducing low-temperature startup times.
Optimizing circuit topology is another key approach to improving low-temperature performance. Traditional hard-switching circuits produce steep voltage and current fluctuations at low temperatures, exacerbating EMI. Soft-switching technologies such as LLC resonant or phase-shifted full-bridge circuits can reduce switching losses through zero-voltage turn-on and zero-current turn-off, distributing EMI spectrum energy over a wider bandwidth. For example, the wireless charging module of a certain vehicle model utilizes an LLC resonant topology, maintaining high efficiency even at -30°C while meeting radiated emission limits.
Low-temperature filtering and anti-interference design must balance performance and reliability. A three-stage filter structure (common-mode inductor + X/Y capacitor + differential-mode inductor) at the input effectively suppresses the deterioration of battery ripple noise at low temperatures. For example, integrating a high-inductance common-mode inductor and a low-temperature-resistant Y capacitor at the input attenuates common-mode noise, ensuring stable operation of the control circuit. Furthermore, the PCB layout adheres to the principle of "strong current-weak current separation," eliminating ground loop interference through single-point grounding, further enhancing the system's anti-interference capabilities.
Redundant design is the last line of defense for ensuring low-temperature reliability. Some models utilize a dual-channel independent control architecture. When the primary channel shuts down due to a low-temperature fault, the backup channel automatically takes over and sends a fault code to the vehicle controller via the CAN bus. Furthermore, a low-temperature redundancy mechanism switches to "battery preheating mode" when the supercapacitor voltage is insufficient, continuously heating the battery with a low current before resuming main power conversion. This design improves system fault tolerance while preventing startup failures caused by a single fault.
Optimizing the low-temperature startup performance of a car electric wireless charging stand requires collaborative innovation across multiple dimensions, including device selection, circuit topology, control algorithms, filter design, and redundancy mechanisms. With the decreasing cost of wide-temperature semiconductor devices and the penetration of AI control algorithms, future in-vehicle wireless charging systems will evolve towards a wider operating temperature range and higher power density, providing solid support for the adaptability of smart electric vehicles to extreme environments.
