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During the 2022 Electrical Competition, Darwen invited four students from the previous national first team with rich competition experience to compare and analyze the component lists for the power supply, signal, and control topics of the 2022 Electrical Competition, provide directions for the questions, and share predicted questions for everyone to train with in the final time. The power supply topic was shared by ltyridium and Jupiter, the signal topic was shared by Four-armed Watermelon, and the control topic was shared by Kirov.
Guessing the questions is not the goal, but to tell everyone what components to prepare, what knowledge to learn, and to assist everyone in the competition. If you happen to guess correctly, feel free to leave a mark!
Add my WeChat: 459888529 (Note: Electrical Competition), join the Darwen Electrical Competition group chat.
1
Power Supply Topic
☞ List Comparison
Horizontal comparison of the requirements for the lists over the past three years and the questions that were asked at the end:
From the list, the 2020 single-phase UPS power requirement was 30W, the 2021 B and C topics required 72W and 60W respectively, and the 2022 requirement for the regulator is above 150VA. The power requirements have increased compared to 2020, so this year the output power is likely required to reach around 50W.
Considering that the DC bus voltage has been increasing in recent years, the switching tube needs to reserve 1.5 to 2 times the withstand voltage. Students need to prepare switching tubes with a withstand voltage of around 100V, preferably around 150V. The most commonly used IRF3205 has insufficient withstand voltage. The auxiliary power supply module also needs high-voltage and high-efficiency chips, such as XL7015, LM5007, LM5164, etc. Generally speaking, two auxiliary power supplies are needed, 12V for gate driving and 5V for circuit driving. Choosing chips with a smaller Iq can further improve efficiency.
☞ Power Supply Preparation Suggestions
The core is to respond to changes with consistency. Everyone can see from past questions that it is actually quite difficult to guess the questions. It can only be said that through the material list, some targeted training questions can be generated. The expression forms of the questions are different, but the actual knowledge used is the same every year.
About Power Level:The core knowledge point in the power supply direction is the half-bridge power level, whether it is boosting or bucking, three-phase or single-phase, the core circuit structure is a half-bridge switch. Once you master the most critical half-bridge switch, you can just piece it together later. Looking at the electrical competition questions over the past ten years, they are all based on the buck circuit. Boosting can be regarded as swapping the input and output positions, and inversion is the conversion of output voltage from DC to AC, while three-phase inversion consists of three half-bridges. Just perfect the most core digital control buck circuit.
About Controllers:Everyone can also familiarize themselves with MSP430/432/C2000 microcontrollers, as the difficulty of traditional single-phase AC-DC has decreased compared to before, and it is possible to limit the processor to improve the distinction. At the same time, it cannot be ruled out that topics requiring Bluetooth host computers may appear in this year’s electrical competition. If everyone has time, they should also familiarize themselves with host computers and similar topics.
About Signal Conditioning Modules:Common voltage and current sampling modules also need to be well prepared, as the accuracy requirement for the electrical competition is relatively high, such as some precision operational amplifiers like INA282, which need to be prepared in advance, including AC voltage and current transformers. Although they are not provided in the list, it is also recommended to prepare them in advance.
About Software Aspects:PWM wave generation, SPWM generation, single-phase power analysis, PID controllers, single-phase phase-locked loops, prepare the code for these parts in advance, and it will be much more efficient when it comes time to debug.
Live Broadcast
Announcement
Tonight and tomorrow night at 8 PM, Darwen will conduct two live broadcasts on power supply topics, inviting former national first-place contestant Chen Jingyang and power supply expert Yu Hao to analyze the component list for power supply topics and the directions for the questions.
In summary, based on past questions and lists, the following practice question was created:
Task: As shown in the figure, create an AC-DC circuit:
Basic Requirements:
1. The input is AC voltage U1 = 18V, the output works in constant voltage mode, and the load resistance is20Ω, Ud = 20±0.1V. (20 points)
2. The input is AC voltage U1 = 18V, the output works in constant current mode. The load resistance is20Ω, and the output current is adjustable from0.1A ~ 2A. (20 points)
3. The input is AC voltage U1 = 14V~21V changes, the output works in constant current mode. The load resistance is25Ω, and the output current is1A, the source adjustment rate<0.5%. (10 points)
4. Measure and display the input frequency, input voltage and current, output voltage and current. (10 points)
5. The input is AC voltage U1 = 18V, the output works in constant voltage mode, Ud = 30V, Id = 1.5A should have an efficiency greater than90%. (10 points)
Extended Requirements:
1. Under the basic requirement5, the AC-DC circuit should have power factor correction function, PF value not less than85%, greater than85% gets1 point, the power factor increases by each 1% gets1 point, more than99% gets full score15 points.
2. Under the basic requirement5, the power factor can be adjusted within100%-85%, with an absolute error no greater than1%. (10 points)
3. Others (5 points)
Note:
1. The work must not use related products for modification.
2. The DC auxiliary power supply of the AC-DC conversion circuit can be purchased power modules(or homemade), powered by the transformer in the figure, and its energy consumption should be included in the efficiency calculation of the AC-DC conversion circuit. No other AC or DC power sources will be provided on-site.
3. The work should be able to operate safely for a sufficient time, and no overheating or other failures should occur during testing.
4. When making, testing convenience should be considered, and reasonable test points should be set as shown in the figure.
5. To ensure operational and testing safety, the work should have necessary over-voltage and over-current protection functions.
6. Power definitions are as follows, where the AC quantity is the effective value:
Where the efficiency calculation formula is:
2
Signal Topic
☞ List Interpretation
This year’s list of signal components is relatively conventional, with no particularly special components. Below is an analysis of each component.
7.FPGA Development System; DSP Development System; Embedded Development System
Equipment List:
1. Wireless Transmitter and Receiver Module
2. Mobile Communication Module
3. A/D, D/A Converter
4. Operational Amplifiers, Voltage Comparators, Multipliers
5. LCD Display
Finally, I wish everyone good results. If I guess part of it correctly, remember to come and kick me.
3
Control Topic
☞ Instrument Equipment and Main Component Analysis
The main components and instrument list for the 2022 Electrical Competition:
This year’s instrument equipment is not much different from previous years. In addition to traditional small cars and drones, two-dimensional gimbals and servos have been added, as well as the relatively mysterious hula hoop.
Based on the equipment, there are several combinations:
1. Gimbal + Servo + Camera + Laser Pointer, using the camera (Raspberry Pi, openmv, etc.) to identify the target, and then using the laser to hit the target, controlling the laser point to move with the target, or making a balance board with a small ball, observing the position of the ball through the camera and controlling the motor to make the ball move along a specified trajectory. Both combinations are relatively basic, mainly testing image processing and proficient application of PID.
2. Regarding the introduction of the hula hoop, we have the following guesses.The first question to consider is whether the hula hoop is in traditional control/measurement questions or in flight control. Based on the question’s wording about having a fixed diameter requirement, we found that the hula hoops on the market can generally be divided into thin-framed, hollow, plastic materials and thick-framed, foam-wrapped, iron materials.
Considering the portability and flexibility of the equipment, we speculate that it should be the former. Another question to consider is whether the hula hoop is static or dynamic. If it is dynamic, is it random oscillation caused by natural suspension, or is it driven by external machinery? Because the hula hoop is relatively light, it can still be driven.
6.6G Control Class Material Download Method: Reply to “Electrical Competition Materials” in “Darwen Says” WeChat
Based on the above guesses, we have made the following judgments: First, it can be made into a smart device similar to a fitness ring, which can calculate the number of rotations, frequency, and other parameters through sensor posture calculations and can reflect in real-time on the host computer. This can use angle and photoelectric sensors from the list, testing posture calculation and wireless communication. We noticed that in the provincial competition years, especially in the last two years, there has been an increased emphasis on the application of neural networks and other artificial intelligence methods in the field of electronic design, such as the epidemic prevention device that appeared a few years ago that detected whether a mask was worn + temperature detection, and the video by Tongji Zihai on posture calculation of the hand, as well as the digital recognition of the medicine delivery car last year.
Second, it can be applied in flight control, allowing drones to pass through hula hoops or perform specified actions related to hula hoops. However, the hula hoop is marked by the outer diameter, and it should be accurately marked by the inner diameter. There are three possibilities here: one is to let the hula hoop serve as a movable landing point. In previous years, there have been tests on whether quadcopters can hover and land, whether they can land in designated areas. The advantage of choosing the hula hoop as a landing area is that compared to the original fixed site, the hula hoop is more convenient to move. Compared to paper that can only be laid flat on the ground, it can also be elevated to three dimensions. It may be set to land at different points in sequence, or it may be required to identify the hula hoop in the designated area and then land. The second situation is that the hula hoop is freely suspended, and the drone needs to identify and choose an appropriate position to pass through, but this situation is very unlikely. The third is that the hula hoop is uniformly rotated by external devices, and identification passes through it, where angular velocity can be an additional scoring point.
Third, combining the hula hoop with measurement questions. Place the gimbal in the center of the hula hoop, the small car follows the track inside and outside the hula hoop, using the camera on the gimbal to detect the movement of the small car, and calculating the angular velocity of the small car based on different radii and identification situations, thereby calculating the linear velocity. It can set requirements for the car to walk at specified angles and other basic requirements within a specified time.
Regarding the equipment list, there has been a significant change this year. Last year, TI’s main control was placed in the components and equipment, while this year it is directly placed in the instruments and meters, which is quite clear. Therefore, it is necessary to consider the possibility that the competition questions may limit the main control. For control questions, the performance of the MSP and C2000 series is sufficient, but compared to the STM32 series, development is not so convenient. Therefore, during preparation, it is necessary to look more at the MSP and C2000 series. In some image processing questions, the requirements for Raspberry Pi, Jetson, and other boards are higher, so preparation should also consider Linux and image-related training.
☞ Prediction Questions
Based on Guess One, the following prediction question was created:
Task:
As shown in the figure, use a two-degree-of-freedom gimbal, motor, disc, magnetic stickers, camera, laser pointer, Hall sensor, and other components to create a laser tracking system. The rotation of the gimbal will cause the laser beam to point in different directions. A metal disc with a diameter of 300mm is placed directly in front of the gimbal. The front of the disc is covered with white paper, and a circle with a diameter of 250mm is drawn. The disc is co-axially connected to the motor, which can drive the disc to rotate. The front of the disc is attached with red, yellow, and blue magnetic stickers (magnetic stickers with a diameter not exceeding 30mm), and the tracking system must make the laser beam land on the corresponding magnetic sticker according to the competition requirements.
Requirements:
1. After powering on the system, the laser beam points to the center of the disc and falls within a circle with a radius of 2.5cm at the center of the disc (the black area in the figure).
2. Place a magnetic sticker on the ring, with the position and color randomly determined. After placing it, trigger it by pressing a button to drive the motor to rotate the disc, moving the magnetic sticker to the 12 o’clock position of the disc.
3. Based on step 2, trigger by pressing a button to drive the gimbal to make the laser beam hit the magnetic sticker.
4. Based on step 3, trigger by pressing a button to make the disc rotate clockwise or counterclockwise at a constant speed of 30 seconds/revolution, while the laser landing point follows the magnetic sticker. After 2 revolutions, the disc stops rotating.
5. Based on step 4, place red, yellow, and blue magnetic stickers on the ring at the same time, trigger by pressing a button to make the disc rotate clockwise or counterclockwise at a constant speed of 30 seconds/revolution, while the laser landing point follows the red, yellow, and blue magnetic stickers in sequence, switching to the next magnetic sticker every 20 seconds. After 2 revolutions, the disc stops.
☞ Preparation Experience
Last year, we focused on “reprogramming” the development boards and various modules during preparation. In the past, every time we encountered a new project during training, we would create a new project, paste the code, and reconfigure the clock, sensors, and other modules. This approach is feasible in regular training, but in the tense environment of the competition, it wastes time and often leads to disagreements during handovers with teammates due to different programming habits.
Therefore, during the summer preparation period, we developed a set of code standards, packaging the code for sensors (angle sensors, encoders, etc.), clock configuration (timers, etc.), communication protocols (UART, IIC, SPI), and other hardware, continuing to encapsulate functions based on the original code, simplifying the configuration process as much as possible, so that we only need to input a few simple parameters.
For the simplest UART protocol, in the MSP series, using UART first requires initialization, including pin selection, register selection, enabling, and interrupt configuration. Just initializing requires copying large sections of code, and many parameters need to be changed when modifying pins. So why not encapsulate all this code into a function? For example, using a switch-case statement, every time you configure, you only need to fill in one parameter. Filling in 0 initializes UART0, and filling in 1 initializes UART1, which can reduce configuration time and make our business code more concise. For example, the UART transmission function provided by MSP can only transmit one character at a time, so we can continue to encapsulate functions for transmitting strings, integers, and floats, and add functions for converting between integers and strings, thus constructing our own communication protocol library. The same applies to other sensors, motor modules, and even commonly used algorithms (PID, Kalman filtering, etc.).
TI’s microcontrollers do not have programming tools as convenient as Cube MX, so it is necessary to prepare your own general library in advance, which can be called at any time during the competition.
END
Recommended Reading for Electrical Competition
List Interpretation + Signal Class Special Session>>>
N Ways to Play with Hula Hoops (Measurement and Control Question Proposition Prediction and Preparation Suggestions)
A Topic National First: How to Do FFT with Low Error Frequency Bandwidth? Sequential Sampling is the Secret
C Topic National First: Can Two DC-DC Conversions Solve C Topic?
D Topic National First: 3 Jetson Nano Makes Node Data Processing Fly, Awesome!
E Topic National Second: Is the High-Frequency Question Complex? AM Modulation Easily Achieves Digital-Analog Mixed Transmission
F Topic National First: Dual K210 + OpenMV Support, Strongest Tracking, Recognition Without Pause
G Topic National Second: Flight Vehicle Program Using Optical Flow is Inferior! This High-Precision Indoor Positioning Program is Worth Having
J Topic TI Cup: 6 Types of Waveform Recognition Measurement, Multiple Fitting Algorithms, Top of TI Cup
K Topic National First: LED Stable Adjustable Table Lamp is Enough with STC8 Microcontroller
Power Supply Topic Special Session, Summary of Key Points of Question Prediction>>>
Control Class Special Session, Summary of Key Points of Question Prediction>>>
Preparation for Electrical Competition: Knowledge Reserve/Training Cases/Question Analysis/Microcontroller Learning
Ultimate Sprint for Electrical Competition: Analysis of Key Points from Previous (Power Supply) Real Questions! What to Do in 4 Days and 3 Nights?
1. 2020 TI Cup Electrical Competition Response Ideas Reference for Each Topic
2. 2020 National Electrical Competition (Provincial Competition) Question Prediction
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We are Nimo, the founder of Darwen, a girl who only talks about technology and does not flirt with men. Darwen is an online education platform aimed at serving professionals in the electronics industry, providing skill training videos that cover popular topics in various subfields, such as embedded systems, FPGA, artificial intelligence, etc. It tailors layered learning content for different groups, such as common knowledge points, disassembly assessments, electrical competitions/intelligent vehicles/postgraduate entrance examinations, etc. Welcome to follow.
