Current zero-crossing detection and dead zone compensation method used for frequency converter

Abstract

The invention relates to the technical field of power electronics, and aims to provide a current zero-crossing detection and dead zone compensation method used for a frequency converter. The method comprises the following steps of: (1) performing OR operation on drive signals of Wx and reversed Wx of an upper bridge arm and a lower bridge arm; taking the drive signal on which the OR operation is performed as a clock signal of a D trigger; performing isolation and transform on an output voltage Ux of the frequency converter to obtain a high-low level Sx serving as an input signal of the D trigger; and acquiring an output signal Qx; (2) judging the polarity of an output current within a dead time according to the Qx; (3) judging whether the Qx is flipped in each switch period Ts; and (4) determining the state of the output current in the switch period according to the number of flips Nf of the Qx in each switch period Ts. In inverted power supplies such as the frequency converter and the like, by using the method, current distortion and torque pulsation caused by the inaccuracy of current polarity detection and the inaccuracy of the dead zone compensation in a reciprocating zero-crossing stage of a current can be greatly avoided, and the waveform of the output current can be improved greatly so that the waveform is closer to a sine wave. Therefore, output torque is greatly improved.

Description

technical field The invention belongs to the technical field of power electronics, and in particular relates to a current zero-crossing detection and dead zone compensation method used in a frequency converter. Background technique The main circuit of inverter power such as frequency converter is a bridge circuit composed of switching devices. In the bridge circuit, the method of pulse width modulation is generally used for control, that is, the devices of the upper and lower bridge arms are turned on in turn to realize the control of the output voltage and current. Since there is a delay in the device, and the turn-on delay and the turn-off delay are different, in order to avoid the device damage caused by the simultaneous conduction of the upper and lower bridge arm devices, in various frequency conversion power supplies using pulse width modulation methods, set There is a dead time, that is, the rising edge of the driving signal is delayed for a certain time. During the...

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Problems solved by technology

In this method, the CE voltage is detected by adding hardware, and the hardware used is all fast devices, which will greatly increase the manufacturing cost

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