Lecture 5 - AC Power, Analog to Digital Conversion PDF

ECOR1044: Boolean Logic and ADC AC Power Analog to Digital Conversion 1 History › Edison was a prolific inventor holding more than 1000 US patents. › His first patent was for the electric vote recorder, granted in 1869. › Edison's major innovation was the establi...

ECOR1044: Boolean Logic and ADC AC Power Analog to Digital Conversion 1 History › Edison was a prolific inventor holding more than 1000 US patents. › His first patent was for the electric vote recorder, granted in 1869. › Edison's major innovation was the establishment of an industrial research lab in 1876. › After many experiments, the first Thomas Edison successful light bulb was in 1879. 1847-1931 › This bulb lasted 13.5 hours. › In 1880, first commercially practical incandescent light bulb and Edison Illuminating Company was founded to develop an electric "utility" to compete with the existing gas light utilities. 2 History › Tesla was a Serbian-American inventor best known for AC power. › In 1884, Tesla emigrated to United States to work for Edison. › Tesla resigned after 6 months because of a $50K bonus. › Soon after leaving the Edison company, Tesla started working on patenting an arc lighting system. Nikola Tesla 1856-1943 › Two investors financed the idea and after it was up and running in 1886, they formed a new utility company, leaving Tesla's company and the inventor penniless. › In 1887, Tesla developed an induction motor that ran on alternating current. 3 History: War of Currents › In 1888, Tesla’s AC patents were licensed. › As Edison expanded his DC power delivery system, he received stiff competition from companies installing AC systems. › DC supply was limited to about one mile distance from the plant. Nikola Tesla Thomas Edison 1856-1943 1847-1931 › With transformers (1885–1886), it became possible to transmit AC long distances over thinner and cheaper wires, and "step down" the voltage at the destination for users. › Power electronics and semiconductor devices emerged in 1950s. 4 AC Sources AC sources are periodic in time (same amplitude). The angular frequency is defined as, After an initial “transient time,” an AC current will flow in the circuit as, 5 Resistive load 6 Inductive load 7 Capacitive load 8 Summary 9 Power (Active, Reactive, Apparent) Active Power (KW) is the power that actually powers the equipment and performs useful work. Reactive Power (KVAR) is the power that a magnetic equipment (transformer, motor, relay) needs to produce the magnetizing flux. Apparent Power (KVA) is the “vector summation” of KW and KVAR. 10 Power Factor P.F. should be close to unity 11 Analog versus Digital Signals As mentioned earlier analog signals have an infinite number of increments, therefore when we plot a voltage signal for example we get a smooth curve: Analog As digital signals have a limited number of values, we instead see something similar to the following: Digital 12 Analog to Digital Converter (ADC) ✓ An Analog-to-Digital Converter (ADC) is an essential device to convert continuous analog signals to discrete digital values. ✓ ADCs allow digital systems, such as microcontrollers and computers, to process real-world analog data like temperature, voltage, or pressure, which are inherently analog in nature. ✓ Signal Conversion: ADCs convert an analog input (e.g., voltage) into a corresponding digital output. This is done by sampling the analog signal at regular intervals and quantizing the sampled values into a finite set of digital codes. ✓ Digitization Process: The analog signal is divided into discrete steps based on the resolution of the ADC. The more bits the ADC has, the finer the resolution, allowing for a more accurate representation of the original signal. 13 Key Parameters of ADCs Resolution: The resolution of an ADC is determined by the number of bits it uses to represent the digital output. Common resolutions include 8-bit, 10-bit, 12-bit, or 16-bit. Higher resolution provides greater precision. Sampling Rate: This refers to how frequently the ADC samples the analog signal, usually measured in samples per second (SPS). Input Range: The input voltage range of the ADC defines the minimum and maximum voltages that the ADC can measure. Any voltage outside this range may result in incorrect conversion. 14 Challenges of ADCs Noise Sensitivity: ADCs are sensitive to noise, which can degrade the accuracy of the conversion. Proper shielding, filtering, and careful design can minimize this effect. Power Consumption: Some types of ADCs, especially high-speed variants like flash ADCs, consume considerable power, making them unsuitable for low-power or portable applications. Trade-off Between Speed and Accuracy: High-precision ADCs may operate at slower speeds and high-speed ADCs may have less precision. So, Designers must choose the appropriate ADC type and configuration based on the application's needs. 15 Applications of ADCs Sensors: ADCs are used to convert analog sensor data (e.g., from temperature, pressure, or light sensors) into digital form for further processing by microcontrollers or computers. Data Acquisition Systems: ADCs are a core component in systems that gather and process data from the physical world, such as in environmental monitoring, industrial automation, and biomedical devices. Communication Systems: ADCs are used in digital signal processing (DSP) for converting analog signals, such as audio and radio waves, into digital form for encoding, transmission, or analysis. Control Systems: In control applications, ADCs help digitize real-time sensor data, which is then used by digital controllers (e.g., PID controllers) to regulate actuators and systems. 16 Applications of ADCs Audio and Music: Converting sound waves into digital form (e.g., MP3 encoding). https://cecm.indiana.edu/361/digitalaudio1.html Sensors: Temperature, pressure, and light sensors convert analog signals for microcontroller use. https://www.researchgate.net/figure/Typical-diagram-of-AI-system-with-sensors-ADC-and-processing_fig1_337630402 17 ADCs Working Principle Sampling: The continuous analog signal is sampled at discrete intervals (sample rate). The higher the sample rate, the more accurate the representation. Encoding/Quantizing: The sampled signal is approximated to the nearest value within a defined range. Key Parameters: Sampling Rate: Determines how often the signal is measured. Resolution: The number of bits used to represent each sample. 18 ADCs: Old vs. New Models Resolution Old model: New model: ✓ Typically, 8-bit or 10-bit resolution. ✓ ADCs now have 12-bit, 16-bit, 18-bit, and even 24-bit resolution. ✓ Limited precision, sufficient for ✓ Higher resolution provides greater simpler applications like early audio precision, enabling use in applications systems or low-end microcontrollers. requiring detailed measurements like medical imaging. 19 ADCs: Old vs. New Models Conversion Speed Old model: New model: ✓ Conversion speeds were relatively ✓ Modern ADCs are much faster, slow, typically in the range of capable of reaching speeds in the kilosamples per second (kSps). megahertz (MHz) and even gigahertz (GHz) range. ✓ Used in applications where speed was ✓ Fast enough for high-speed data not critical, such as temperature acquisition in communication sensing or low-frequency signals. systems, radar, or video applications. 20 ADCs: Old vs. New Models Power Consumption Old model: New model: ✓ They are less power-efficient due to ✓ Modern ADCs are much more power- older transistor technology. efficient, due to improvements in semiconductor technology. ✓ Power consumption was a concern in ✓ Low-power ADCs are now available for portable and battery-powered portable and embedded systems, applications. consuming significantly less power, making them ideal for IoT and mobile devices. 21 Choosing the Right ADC Resolution: How precise do your measurements need to be? Sampling Rate: How fast does the signal change, and how often do you need to sample it? Power Consumption: Important for battery-powered systems. Cost: Higher performance ADCs are generally more expensive. 22 Resolutions of ADCs Error 23 Time (s) Analog to Digital Converter If we start with the analog signal, how do we convert it to the digital ‘equivalent’? We use a ‘sample and hold’ system 24 What does the ADC do? Converts analog signals into binary words. These binary words can be in different length 2, 4, 8, 10-bit. The more bits the binary number has, the higher the resolution of the analog to digital converter (ADC , A/D, or A to D). 25 Analog to Digital Conversion - 3 Steps A 3-Step Process – Sampling – Conversion of a continuous signal to a discrete-time (DT) signal – Quantizing – Conversion of a DT signal to discrete amplitude signal – Encoding – Conversion of a discrete signal to binary word 26 Analog to Digital Conversion Exp. 1: Convert a time varying signal of 0-7V to a digital using a 3-bit ADC. 27 Quantization Details Resolution/Quantization Step-Size (Q) – The smallest voltage that can be encoded digitally, in other words the voltage represented by the least significant bit. – It describes the general performance of an ADC, how finely it can convert signals. – The quantization step size (Q) can be calculated as follows: 𝑽𝑴𝑨𝑿 − 𝑽𝑴𝑰𝑵 𝑸= 𝑵𝑺𝑻𝑨𝑻𝑬𝑺 28 Quantization Details Exp. 2: Output Discrete Voltage - You have a 0-10V signal. Separate the States Ranges (V) voltage range such that it fits into a 3-bit 0 0.00≤V≤1.25 number. 1 1.25