Summary
The UCD3138 is the latest generation of digital power controllers from Texas Instruments and was officially released in the first quarter of 2012. Compared with the previous generation digital power controller UCD30xx, it has important improvements in many aspects, more features and more powerful performance. This paper is based on a switching power supply with a hard-switched full-bridge (full-wave rectification on the secondary side) topology. The hardware design, software configuration, and measured data of the cycle-by-cycle protection function (cycle by cycle limitaTIon) of the UCD3138 are described in detail. While understanding the above functions, you can clearly understand the advantages of UCD3138. References are given at the end of this article.
1. Design and implementation of cycle-by-cycle protection
The cycle by cycle protection function is an important improvement of the UCD3138 compared to the UCD30xx. It is designed to achieve cycle-by-cycle protection on the primary side, enabling fast response and protection in situations such as input voltage surges and output short circuits.
1.1 Description of the cycle-by-cycle function
Each DPWM module inside the UCD3138 chip has one and only one cycle by cycle (CBC) hardware module, as shown in Figure 3 below. When the CBC module receives the trigger signal (FAULT), the CBC module responds immediately to limit the duty cycle of the current DPWM A and DPWM B, which implements the cycle by cycle protection.
Figure 1: CBC module inside UCD3138
1.2 Hardware design of cycle-by-cycle function
As shown in Figure 2 below, this circuit is the primary current detection circuit. With a current transformer (ratio 100:1), the voltage obtained at the AD04 network reflects the magnitude of the primary current. The relationship is: 
. The voltage at this network will be transferred to the UCD3138 chip via an analog comparator.
Figure 2: Primary current detection circuit
A rice cooker or rice steamer is an automated kitchen appliance designed to boil or steam rice. It consists of a heat source, a cooking bowl, and a thermostat. The thermostat measures the temperature of the cooking bowl and controls the heat. Complex rice cookers may have many more sensors and other components, and may be multipurpose. Cooking rice has traditionally required constant attention to ensure the rice was cooked properly, and not burnt. Electric rice cookers automate the process by mechanically or electronically controlling heat and timing, thus freeing up a heating element on the cooking range that had to be otherwise occupied for rice cooking. Although the rice cooker does not necessarily speed up the cooking process, with an electric rice cooker the cook's involvement in cooking rice is reduced to simply measuring the rice, preparing the rice properly and using the correct amount of water. Once the rice cooker is set to cook, the rice will be cooked with no further attention.
Features:
For modern home rice cookers, the smallest single-person model cooks 1 rice cup (180 ml), whereas large models can cook 10 cups. Commercial models can cook 20 or more cups. As a possible source of confusion, model specifications and names may list either cooked or uncooked capacity. Rice roughly doubles in size during cooking; therefore, a 10 cup (uncooked) rice cooker can produce up to 20 cups of cooked rice. The prices vary greatly, depending on the capacity, features, materials used, and the country of origin.
The majority of modern electric rice cookers are equipped with a stay-warm or keep-warm feature, which keeps the rice at an optimal temperature for serving without over-cooking it. Some gas cookers also have electric stay-warm mechanism. However, the usefulness of this feature degrades over time, a microwave may be more energy efficient or better suited to reheat rice that will sit longer than four hours.
Some rice cookers use induction heating, with one or more induction heaters directly warming the pot. This can improve energy efficiency.
Most modern rice cookers use aluminium for the inner cooking bowl. There are some models that use stainless steel instead of aluminium. Various other materials, such as copper, pure carbon, ceramic, and diamond powder coating, may be used for higher heat conductivity or better taste.
The pressure-cooking models can raise the water's boiling point higher, e.g., from 100 °C at 1.0 atm up to about 110 °C at 1.4 atm, which speeds cooking. The pressure-cooking models can also be used in high altitude areas, where the boiling temperature is below 100 Celsius. Pressure cookers are also suitable for cooking brown rice (which contains oils and bran fiber that cook differently from pure white rice starch). Some pressure rice cookers have a varying pressure control mechanism (named the "dual-pressure" method) that creates repeated pressure/release cycles during the cooking.
There also exist mechanisms to collect and return the boiled over liquid to the inner rice bowl.
Many cookers now have microprocessor-controlled cooking cycles, which are often used to adjust for rice and cooking type.
Applications
Rice cookers are typically used for the preparation of plain or lightly seasoned rice. Each rice cooker model may be optimized to cook a certain type of rice best. For example, most Japanese rice cookers are optimized for cooking Japanese rice and may not be the best for other types of rice[citation needed], although cooking time can be lengthened simply by more water.
The typical method of cooking long grain rice is boil-and-strain and/or steaming method. The absorption method used in Japanese rice cookers will produce slightly different texture and taste, usually stickier rice.
Brown rice generally needs longer cooking times than white rice, unless it is broken or flourblasted (which perforates the bran).
Different varieties of rice need different cooking times, depending on their grain size, grain shape, and grain composition. There are three main types of Asian rice: Oryza sativa subsp. indica, i.e., Indian rice (long grain rice, e.g., basmati rice and Thai jasmine rice), O. sativa subsp. javanica, i.e., Java rice (large grain rice) and O. sativa subsp. japonica, i.e., Japanese rice (medium grain rice, e.g., Calrose rice, short grain rice, e.g., most Japanese rice and risotto rice).
African rice, Oryza glaberrima, is an entirely separate species, but can be cooked in the same way. Zizania is not even in the same genus, although it is often called a rice (or "water oats"); it, too, can also be cooked in a rice cooker.
A rice cooker can be used to cook many boiled or steamed granular foods, such as pot barley, bulgar wheat, and dal. Provided the ingredients have similar cooking times, a rice cooker can cook mixtures such as khichdi. Some rice cookers can be used as automated couscoussiers, cooking couscous and a stew simultaneously.
Rice Cooker
Rice Cooker,Drum Rice Cooker,Deluxe Rice Cooker,Straight Rice Cooker
Guangzhou Taipeng Electrical Appliances Technology CO., LTD. , https://www.taipengelectric.com