(C-Wireless Charging Electric Car) Shaanxi Province First Prize_Topic C_Xi'an University of Electronic Science and Technology

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(C-Wireless Charging Electric Car) Shaanxi Province First Prize_Topic C_Xi'an University of Electronic Science and Technology [Copy link]

Description of the work and experience in participating in the competition:

The wireless charging electric car design completed by this team has two major parts, circuit design and body design.

The circuit part consists of five parts. The first is the boost circuit based on the DC-DC boost chip XL6009, which boosts the 5V source voltage to 12V to increase the charging rate. The second is the radio transmitter based on XKT-412 and XKT-335, which converts DC power into AC power and transmits energy to the receiving coil through the electromagnetic induction of the coil. The third is to form a rectifier bridge circuit through four diodes to perform full-wave rectification to charge the farad capacitor. Fourth, PMOS (AO3401) is used as the control circuit of the electronic switch to achieve self-starting. Fifth, the motor drive circuit based on TI's buck-boost, DC-DC chip TPS63020 makes the motor drive voltage stable and maximizes the use of the power in the farad capacitor. The body design uses lightweight PLA material, the core frame is made by 3D printing, and the reduction hollow cup motor is selected to cooperate with the gear transmission to increase the torque and improve the climbing ability.

This competition tested our abilities in all aspects. 1. Understanding and use of chip parameters. 2. Skillful and accurate reading of data manuals. 3. Connection and debugging of the entire circuit. 4. Engineering ability and hands-on ability, the use of 3D printers, the use of PCB plate making machines, and the use of various engineering machines. 5. Unity and cooperation among groups. This competition has sublimated our theory into real life, opened the door to the electronic world, improved professional ability, and had a deeper understanding of our profession.

Actual pictures of the works:

Wireless Charging Electric Car

Abstract

Our team designed and produced a wireless charging electric car. The system is based on DC-DC conversion circuit and wireless charging device, with farad capacitor as energy storage device, hollow cup motor to drive the car, and PMOS control, so that the car automatically starts when the wireless charging transmitter stops charging.

The reasonable bridge rectifier circuit of the receiving device effectively reduces energy loss, and the DC-DC conversion circuit adopts the energy-saving mode of TPS63020 to further reduce power consumption. Based on theoretical analysis and actual experiments, the optimal capacitance and series-parallel connection mode of the farad capacitor are obtained. The car body uses lightweight PLA material as much as possible, and the core frame of the load-bearing part is 3D printed by itself. The gear transmission structure is designed to reduce the friction of the transmission and reduce energy loss. The motor selection is optimized in combination with the torque and power requirements, and a single motor rear-drive drive mode is adopted, which is both energy-saving and improves the climbing ability.

After cascading and debugging, the system meets all the requirements of the topic and optimizes the efficiency as much as possible.

Keywords: Wireless charging DC-DC conversion Low power consumption

1. Scheme demonstration

The main parts of the system are shown in Figure 1, including wireless charging device, rectifier circuit, automatic control circuit for detecting charging status and starting the car, and the car.

Wireless Charging Solution

Electromagnetic induction wireless charging. The electromagnetic induction wireless charging device is similar to a transformer. An alternating current is passed through the transmitting coil, and an electromotive force is induced in the receiving coil to transmit energy.

Self-starting solution selection

Use PMOS. The alternating current received by wireless transmission is rectified and connected to PMOS. When charging is completed, the PMOS control circuit disconnects the enabling drive circuit to achieve self-starting.

2. Circuit and Program Design

The system uses a DC regulated power supply that automatically switches between constant current and constant voltage modes to obtain a 5V, no more than 1A power supply. After the input voltage is boosted to 12V, it powers the transmitter of the wireless charging device. The DC-AC converter and inverter of the transmitter work to generate an alternating current. The alternating current in the receiving coil is input into the farad capacitor for charging through the bridge rectifier circuit, and is also input into the charging status judgment circuit through the half-wave rectifier circuit. When charging is completed, the PMOS of the charging status judgment circuit enables the DC-DC conversion circuit with TPS63020 as the core, and the car starts to move.

The wireless charging device of this system adopts the principle of electromagnetic induction and uses the XKT412 chip to assist in improving the efficiency of wireless transmission. The receiving device is composed of a bridge rectifier circuit and a start-up control circuit. The bridge rectifier circuit effectively reduces energy loss. The capacitor releases energy to the DC-DC conversion circuit with TPS63020 as the core, outputting a stable 3.3V voltage. The DC-DC conversion circuit adopts the energy-saving mode of TPS63020 to further reduce power consumption. The car body uses lightweight KT board and PLA as much as possible, and the core frame of the load-bearing part is 3D printed by itself. The transmission structure is reasonably designed to reduce the friction of the transmission and reduce energy loss. The motor adopts rear-drive drive mode to improve the climbing ability.

The system frame is shown in the figure:

The transmitter is divided into a voltage stabilization circuit and a wireless charging transmission circuit. The voltage regulator circuit is shown in the figure.

After voltage regulation, the DC is output to the modulation chip, and an alternating current is obtained through the L2 coil, as shown in the figure.

The receiving circuit rectifies the alternating current and uses PMOS to detect the charging status. When charging stops, the PMOS is turned on and the TPS63020 chip is enabled, as shown in the figure.

After the rectification circuit and the automatic control circuit, the motor is driven through the DC-DC conversion circuit with TPS63020 as the core. As shown in the figure.

In order to increase the climbing height of the car, we designed a lightweight body structure, modified the rubber tires to increase grip, and 3D printed the transmitter support structure to reduce the distance between the transmitting coil and the receiving coil. Align the axis of the transmitting and receiving coils, and reasonably adjust the coil wire diameter and number of turns. After several experiments, the motor with a reasonable speed was obtained, and the corresponding gear transmission structure was designed based on the motor parameters. The frequency of the alternating current in the transmitter was increased to improve the efficiency of wireless charging, and the DC-DC conversion circuit and charging status detection circuit after the receiving coil were optimized to reduce power consumption and reduce vehicle weight.

3. Summary

This system is based on a wireless charging device and a DC-DC conversion circuit, and is designed with a lightweight and efficient mechanical structure. In particular, the control circuit design and the wireless charging device are optimized many times, and the best inclination angle is obtained through repeated tests. After the final cascade and debugging, the electric vehicle finally climbs to a height h=lsinθ as large as possible after each 1 minute of charging.

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The receiving circuit rectifies the alternating current and uses PMOS to detect the charging status. When charging stops, the PMOS turns on and enables the TPS63020 chip, as shown in the figure.

After the rectification circuit and the automatic control circuit, the motor is driven by the DC-DC conversion circuit with TPS63020 as the core. As shown in the figure.

In order to increase the climbing height of the car, we designed a lightweight body structure, modified the rubber tires to increase grip, and 3D printed the transmitter support structure to reduce the distance between the transmitting coil and the receiving coil. Align the axis of the transmitting and receiving coils, and reasonably adjust the coil wire diameter and number of turns. After several experiments, the motor with a reasonable speed was obtained, and the corresponding gear transmission structure was designed based on the motor parameters. The frequency of the alternating current in the transmitter was increased to improve the efficiency of wireless charging, and the DC-DC conversion circuit and charging status detection circuit after the receiving coil were optimized to reduce power consumption and reduce vehicle weight.

3. Summary

This system is based on a wireless charging device and a DC-DC conversion circuit, and is designed with a lightweight and efficient mechanical structure. In particular, the control circuit design and the wireless charging device are optimized many times, and the best inclination angle is obtained through repeated tests. After the final cascade and debugging, the electric vehicle finally climbs to a height h=lsinθ as large as possible after each 1 minute of charging.

cn/data/attachment/forum/201809/12/174949u48w40glgslc8rwy.png.thumb.jpg[/img]

The receiving circuit rectifies the alternating current and uses PMOS to detect the charging status. When charging stops, the PMOS turns on and enables the TPS63020 chip, as shown in the figure.

After the rectification circuit and the automatic control circuit, the motor is driven by the DC-DC conversion circuit with TPS63020 as the core. As shown in the figure.

In order to increase the climbing height of the car, we designed a lightweight body structure, modified the rubber tires to increase grip, and 3D printed the transmitter support structure to reduce the distance between the transmitting coil and the receiving coil. Align the axis of the transmitting and receiving coils, and reasonably adjust the coil wire diameter and number of turns. After several experiments, the motor with a reasonable speed was obtained, and the corresponding gear transmission structure was designed based on the motor parameters. The frequency of the alternating current in the transmitter was increased to improve the efficiency of wireless charging, and the DC-DC conversion circuit and charging status detection circuit after the receiving coil were optimized to reduce power consumption and reduce vehicle weight.

3. Summary

This system is based on a wireless charging device and a DC-DC conversion circuit, and is designed with a lightweight and efficient mechanical structure. In particular, the control circuit design and the wireless charging device are optimized many times, and the best inclination angle is obtained through repeated tests. After the final cascade and debugging, the electric vehicle finally climbs to a height h=lsinθ as large as possible after each 1 minute of charging.

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