Low-harmonic AC motor controller and control method

A technology of AC motor and control method, applied in the direction of AC motor control, DC motor speed/torque control, control system, etc., can solve problems such as interference, achieve the effect of reducing harmonic and electromagnetic wave radiation, and small harmonic interference

Active Publication Date: 2004-04-07
NINGBO FUJIA IND
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  • Abstract
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Problems solved by technology

However, it still adopts the method of phase-shift control. When the power reaches a certain level, it

Method used

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  • Low-harmonic AC motor controller and control method
  • Low-harmonic AC motor controller and control method
  • Low-harmonic AC motor controller and control method

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Embodiment Construction

[0034] Referring to the accompanying drawings, specific embodiments of the present invention will be described in detail.

[0035] figure 1 The electrical principle block diagram of the present invention is given, the low-harmonic AC motor controller is powered by an AC power supply, and a DC power of +5V is output through the power supply circuit to provide a DC working voltage for the controller. The zero-crossing detection circuit and the control input circuit are respectively It is connected with the corresponding input port of the single-chip microprocessor MCU, and the thyristor drive circuit and the bidirectional thyristor are connected in series with an output port of the MCU in turn. Among them, the zero-crossing detection circuit converts the AC sine wave into a square wave signal and inputs it to the external interrupt port of the MCU. When the AC voltage crosses zero, the MCU is interrupted; the control input circuit transmits the received motor output power setti...

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Abstract

The low-harmonic AC motor controller includes monochip microprocessor MCU, zero-crossing detection circuit, control input circuit, SCR drive circuit, bi-directional SCR and power circuit. By means of zero-crossing triggering to alter the conducting in set period and phase shift triggering, the on/off of the bi-directional SCR is controlled to output continuously adjustable voltage. The control process includes the following steps: initializing before reading the set output power, performing the output power control operation, and producting interruption by the MCU after the zero-crossing detection circuit detects the AC zero-crossing signal to output triggering pulse. The controller and the control method make full use of the zero-crossing triggering and phase shift control, reduce greatly the harmonic and electromagnetic radiation, and control the output of great power AC motor in continuously adjustable mode radically.

Description

technical field [0001] The invention relates to an AC motor control device and method, in particular to a low harmonic AC motor power controller and control method used in electric tools. Background technique [0002] Currently commonly used motor output power control circuits such as Figure 6 As shown, changing the conduction angle θ of the bidirectional thyristor T1 can adjust the AC voltage of the motor. In the half cycle when the L terminal of the power supply is positive, the bidirectional thyristor T1 is triggered to conduct forward at the moment of the control angle α, and the bidirectional thyristor T1 is automatically turned off when the power supply voltage crosses zero; similarly, in the second half of the cycle, the L terminal of the power supply is negative , starting from the voltage crossing zero, delaying the same control angle α triggers the reverse conduction of the triac T1, so a notch-angle sine wave symmetrical to the first half cycle is obtained on the...

Claims

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Application Information

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IPC IPC(8): H02M5/257H02P27/02
Inventor 徐宏
Owner NINGBO FUJIA IND
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