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Pulse width modulator system

A technology of pulse width modulation and signal modulation, applied in the field of pulse width modulator system, can solve the problems of incompatibility and high cost

Inactive Publication Date: 2006-02-15
FREESCALE SEMICON INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the solution to this problem is also expensive due to the use of current sensors and this technology is not suitable for many low cost motor installations

Method used

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Embodiment Construction

[0023] image 3 A pulse width modulator (PWM) system 100 according to the present invention is shown in part block diagram, part logic diagram and part schematic diagram. It is to be noted that the PWM system 100 does not include all parts of the motor system such as the motor itself, these parts are left out for a better understanding of the invention. PWM system 100 generally includes MCU 120 and voltage sensor 140 . and image 3 Transistors 51 and 52, diodes 61 and 62 are shown having the same reference numerals as corresponding parts in FIG. Transistors 51 and 52 and diodes 61 and 62 are connected to motor U as described in detail in FIG. 1 for connection and operation, which will not be described again here. Note that, for discussion purposes, image 3 The currents marked "I+" in , establish such a rule that a positive current flowing into the U-phase terminal of the motor is represented as a positive value. In addition, the voltage at terminal U is marked as "load volt...

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Abstract

A pulse width modulator (PWM) system detects several load current conditions to completely correct for the distortion caused by deadtime insertion when driving an inverter-fed inductive load, such as a three-phase AC motor. The system includes an inexpensive voltage sensor which senses the output voltage at the end of each successive dead time interval in which neither a pullup transistor nor a pulldown transistor is driving. The system includes a programmable PWM, two storage elements such as D-type flip flops, and a memory-mapped register. The register indicate a near-zero load current condition. When it detects this condition, the system changes the duty cycle of the PWM output signals to yield output voltages and currents which more closely approximate a sine wave.

Description

technical field [0001] This invention relates generally to electronic circuits, and more particularly to digital circuits for driving inverter-fed inductive loads. Background technique [0002] The revolution in microelectronics has allowed digital circuits to be used in a variety of control devices. For example, microcontrollers (MCUs) have recently been used to control electric motors in such devices as heating, ventilation, and air conditioning (HVAC), factory automation, variable speed drives, and the like. An MCU generally implements a control function by including a peripheral circuit called a pulse width modulator (PWM) controlled by the MCU. PWM can control the speed and operation of an engine by modulating the pulse width of a signal that drives a power inverter. [0003] An example of such a system is shown in Figure 1, which shows an alternating current (AC) three-phase motor system in part block and part schematic form. The system 20 generally includes an MCU ...

Claims

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Application Information

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IPC IPC(8): H03K7/08H02M7/527H02M7/5387H02P6/14H02P23/00H02P27/08
CPCH02P23/0077H02P27/08H02M2001/385H02M7/53873H02M1/385
Inventor 戴维L·威尔森
Owner FREESCALE SEMICON INC
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