外文資料翻譯--基于c51兼容微處理器單片機的pwm控制器設(shè)計-單片機-資料下載頁
2025-05-12 04:38本頁面
【導(dǎo)讀】率來調(diào)整兩端負荷電壓。這種技術(shù)能用于各種應(yīng)用包括電機、溫度、和壓力的控制，這樣當(dāng)電機的電源打開時，它的速度加快，相反，當(dāng)電源關(guān)閉時，速度下降。種方法需要CPU持續(xù)操作代碼來控制I/O口，以致于CPU不能做其他任何事。在本文中，我們建議在8051單片機里嵌入一個PWM模塊。三種方法調(diào)整占空比和幾個操作模式，以增加用戶彈性。以下這部分解釋PWM模塊和基本功能模塊的結(jié)構(gòu)。這部分還講述了實驗和仿真的結(jié)果驗證了合適的系統(tǒng)操作。通過操作模式，PWM模。塊產(chǎn)生一個或更多的脈寬模塊信號，它們的比率可以自主調(diào)整。PWM模塊初始化，從而啟動其功能。在PWMCON中的其它位的定義，詳見表1. 通過在PWMCON寄存器中設(shè)。獨立PWM輸出模塊對于驅(qū)動負荷很有用，如圖6所示。PWM1電機的信號是沒用的，而當(dāng)PSEL設(shè)置為1時，PWMH和PWML將來自PWM1電機，PWM模塊的互補輸出對已有一個用于產(chǎn)生死區(qū)時間插入的8位計數(shù)器。這種在EDA平臺的仿真結(jié)果已證明了它的和諧性和有用性。
【正文】 mode is used to drive inverter loads similar to the one shown in Figure 7. This inverter topology is typical for DC applications. In Complementary Output Mode, the pair of PWM outputs cannot be active simultaneously. The PWM channel and output pin pair are internally configured through channelselect logic as shown in Figure7. A deadtime may be optionally inserted during device switching where both outputs are inactive for a short period. Fig 7 : Typical Load for Complementary PWM Outputs The Complementary mode is selected for PWM I/O pin pair by setting the appropriate CPWM bit in PWMCON. In this case, PSEL is in effect. PWMH and PWML will e from PWM0 generator when PSEL is set to zero, when the signals from PWM1 generator is useless, whereas PWMH and PWML will e from PWM1 generator when PSEL is set to 1, when the signals from PWM0 generator is useless. In the process of producing the PWM outputs in Complementary Mode, the deadtime will be inserted to be discussed in the following section. Deadtime Control Deadtime generation is automatically enabled when PWM I/O pin pair is operating in the Complementary Output mode. Because the power output devices cannot switch instantaneously, some amount of time must be provided between the turnoff event of one PWM output in a plementary pair and the turnon event of the other transistor. The 2output PWM module has one programmable deadtime with 8bit plementary output pair for the PWM module has an 8bit down counter that is used to produce the deadtime insertion. As shown in Figure 8, the dead time unit has a rising and falling edge detector connected to PWM signal from one of PWM generator. The dead times is loaded into the timer on the detected PWM edge event. Depending on whether the edge is rising or falling, one of the transitions on the plementary outputs is delayed until the timer counts down to zero. A timing diagram indicating the dead time insertion for the pair of PWM outputs is shown in Figure 8a. Fig 8a Deadtime Unit Block Diagram Fig. 8b the Waveforms of PWM Outputs in Complementary Mode Conclusions In this paper, we have designed PWM module based on an 8bit MCU patible with 8051 family. The design can generate 2channel programmable periodic PWM signals with two operation mode, Independent Mode and Complementary Mode in which deadtime will be inserted. The simulation results on the EDA platform have proven its correctness and usefulness.
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