#The 4th LiChuang Competition# Intelligent rapid cooling and heating cup based on high-power H-bridge design

Brief introduction of the work:
Intelligent rapid cooling and heating cup based on high-power H-bridge design, made with ESP8285+IR8726+RZ7886+74 logic circuit.
1. Work details:
Most of the cooling cups or heating cups currently sold can only operate in a single mode, that is, they can only cool or only heat, and few can switch modes. This time, the cooling and heating cup we designed introduced the concept of intelligent Internet of Things. Through ESP8285, it is connected to the Internet of Things platform, and can be remotely controlled for cooling or heating, and can also be started and set the running time. Using this cooling and heating cup is a good choice when colleges and universities prohibit the use of high-power electric heaters. The cooling and heating cup uses 12V power supply, and the power consumption of the whole machine is only 78W, which is safe and reliable.
2. Describe the challenges faced by the work and the problems solved:
Challenges faced:
1. The PCB antenna WIFI signal is weak.
2. The cooling sheet purchased online does not achieve the expected effect.
3. The ESP8285 GPIO is directly connected to the high-power H-bridge, which leads to unstable operation due to excessive power ripple.
4. The fan speed is slow and the wind pressure is small, resulting in unsatisfactory heat dissipation.

Problems solved:
1. Redesign the RF circuit, change it to a π-shaped network, and replace it with a Huaxinke 2.4G ceramic antenna. The modified signal can pass through two walls.
2. We redesigned a special cooling plate, changed the previous arrangement structure of PN particles, modified the thickness of the ceramic plate, and the temperature difference between the front and back sides can reach 65 degrees, which greatly improved the efficiency of the cooling plate.
3. Redesigned PCB using two 74 logic chips, and controlled the high and low levels of the OUT pins of the 74 logic chips by operating the ESP8285 GPIO level, thereby controlling the switching of cooling and heating. The ESP8285 GPIO is directly connected to the high-power H bridge through the 74 logic chip isolation.
4. In order to achieve the best effect, we contacted the fan manufacturer and customized a 5500-rpm high-speed double ball bearing fan. Generally, fans use oil-containing bearings. This type of fan has a short life, low speed, and low cost, while double ball bearings have a long life, high speed, and high wind pressure. But the cost is also relatively high.
3. Describe the key points involved in the hardware and software parts of the work:
Software:
Internet of Things We use TCP client and server to exchange data. After ESP8285 connects to the server, it reports the IO port level status to the server. The mobile phone connects to the server to receive the IO status of ESP8285. The mobile phone sends data to the server and forwards it to ESP8285 to control the device. In this way, relays, temperature sensors, etc. can be controlled, and smart IoT devices such as smart sockets and thermostats can be extended.
Hardware:
We use Espressif ESP8285 as the IoT chip for development. ESP8285 has a built-in 1MB Flash, eliminating the need for an external Flash chip and saving PCB space. Through the GPIO of ESP8285, two 74 logic chips, AND gates and inverters are controlled to control the polarity switching of the RZ7786 high-power H-bridge chip to achieve the switching of cooling or heating mode. At the same time, the H-bridge and ESP8285 GPIO are isolated, making the operation of ESP8285 more stable. Use hardware switches to control the conduction and shutdown of N-MOS tubes to control the switching of cooling plates and fans. In the absence of a network, another hardware switch is used to control the ESP8285 GPIO pull-up and pull-down to control the switching of heating and cooling.
4. List of materials for the work:
The schematic diagram is as follows, and the PCB manufacturing file is in the attachment.
5. Upload pictures of the work:
It takes about 3 minutes, the red light on the left heats up to 102.2 degrees, and the blue light on the right cools down to 5.5 degrees.
Photos of the work:
Exploded view:
Empty PCB photo:
Photo of the patch welding completion:
Use CAD to model the shell:
3D print colorful shell:
6. Open source documents:
See the attachment for open source documents
7. The IoT function demonstration and performance test video is as follows: