JP2008206319A - Power conversion circuit controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a power converter from going out of control and being broken when current detection fails even though there is the problem that, in a power converter for executing current detection, a power converter main circuit 2 tries to maximally output a current, however, no signal is inputted to a protector 4 since a current signal is not fed back from a current detector 9, and therefore, a protection function does not work, consequently, the power converter is broken due to, for example, an overcurrent. <P>SOLUTION: Despite a power converter main circuit of a three-phase PWM inverter device outputs an output voltage while being in an operating state, when an output signal of a current detector becomes a DC or when the output signal of the current detector has equal to a supply voltage of the current detector for a fixed period of time, it is judged that the current detector has failed. The output of the power converter main circuit is turned off by mounting a current FB detector outputting a protection signal to the power converter main circuit. It is possible to prevent the breakage of the power converter due to erroneous wiring or a failure of the current detector 9. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a power converter control technique, and more particularly to a current detector and a protection function of the power converter.

A configuration example of a conventional power converter is shown in FIG. For example, the three-phase power source 1 is connected to the power converter main circuit 2, and the load 3 is connected to the output of the power converter main circuit 2 via the current detector 9. The power converter main circuit 2 converts the input three-phase AC power supply, obtains an output voltage vout having an arbitrary amplitude and frequency, and supplies the output voltage vout to the load 3. The current detector 9 detects the output current of the power converter main circuit 2. The detected output current is detected by the protector 4 as to whether or not the threshold value is exceeded, and if it is overcurrent, the power converter main circuit 2 is stopped. Further, the three-phase two-phase coordinate converter 6 is detected by inputting the current detected by the current detector 9 and the phase command θ output from the speed controller 8 to the three-phase two-phase coordinate converter 6. The output current is converted into two axes to obtain current signals id and iq. The obtained current signals id and iq are input to the current controller 7 together with the q-axis current command value iqref and the d-axis current command value idref which are the outputs of the speed controller 8, and for example, PI control is performed. A q-axis voltage command value vdq is obtained. When the current controller 7 functions correctly, each of the current command values idref and iqref and the output current signal current signals id and iq coordinate-converted by the three-phase two-phase coordinate converter 6 become equal. The obtained biaxial voltage command value vdq is input to the two-phase / three-phase coordinate converter 5 together with the phase command θ which is the output of the speed controller 8 to control the output power supply of the power converter main circuit 2. A voltage command value vref which is a value is obtained. The input of the speed controller 8 is a speed command value ωref. For example, when the load 3 is a motor, the speed command value of the motor is used. When the load 3 is a motor, the speed controller 8 may be configured to detect and feed back the speed and perform speed control by PI control. Alternatively, without detecting the motor speed, the motor speed is estimated from the output of the power converter main circuit 2, and this is used instead of the actual speed feedback to take a deviation from the speed command value, and the speed control is performed by PI control. The structure to perform may be sufficient.
JP 2006-158182 A JP 2005-229733 A

By adopting such a circuit configuration, for example, when the current detector 9 fails or when the output of the current detector cannot be obtained due to a wiring mistake, the current controller 7 is connected to the power converter main circuit 2. Even if the three-phase AC power supply is output, the feedback signals of the output currents id and iq cannot be obtained. Therefore, the current controller 7 determines that a desired output current is not obtained, and controls to increase the output current more and more. Then, the power converter main circuit 2 tries to output current as much as possible, but since no current signal is fed back from the current detector 9, no signal is input to the protector 4, and the protection function is activated. Absent. Thereby, there existed a problem that a power converter device will be destroyed, for example by overcurrent.

  The present invention of claim 1 includes a current command, a current detector, and a current feedback signal output from the current detector. By comparing the current command with the current command and the current feedback signal, In a three-phase PWM inverter device having a current controller that controls the power detector, the power converter main circuit of the three-phase PWM inverter device is in an operating state and outputs an output voltage. When the output signal becomes a direct current, it is determined that the current detector has failed, and a current FB detector that outputs a protection signal is mounted on the main circuit of the power converter.

  The present invention of claim 2 includes a current command, a current detector, and a current feedback signal output from the current detector. By comparing the current command with the current command and the current feedback signal, In a three-phase PWM inverter device having a current controller that controls the power detector, the power converter main circuit of the three-phase PWM inverter device is in an operating state and outputs an output voltage. When the output signal is equal to the supply voltage of the current detector for a certain time, it is determined that the current detector has failed, and a current FB detector that outputs a protection signal to the power converter main circuit is mounted. To do.

  That is, one of a power converter main circuit having a three-phase power source as an input and a load connected to the output via a current detector, an output of the current detector, and an output of a speed controller having a speed command ωref as an input. And a three-phase two-phase coordinate converter that converts a three-phase current into a two-phase current, a current command iqref that is one of the outputs of the speed controller, a d-axis current command value idref, A current controller that outputs the two-phase voltage command signal vdq by inputting the two-phase converted current signals id and iq that are the outputs of the three-phase two-phase coordinate converter, and the output of the speed controller A two-phase three-phase coordinate converter for calculating a three-phase voltage command value vref by inputting a phase command θ and an output vdq of the current controller, and an output signal of the current detector as an input, the power converter main circuit The output current of In the power conversion device controlled by the power conversion circuit control device configured by the protector having the function of turning off the output of the power converter main circuit, the output signal of the current detector becomes DC. A current FB detector is mounted to stop the power converter main circuit if there is no current detection signal by detecting that the current detector has failed.

According to the present invention, it is possible to prevent the power converter from being damaged due to incorrect wiring or failure of the current detector 9.

According to the present invention, the presence or absence of the output of the current detector is detected by attaching a current FB detection device with a simple configuration for the purpose of preventing destruction of the power conversion device due to incorrect wiring or failure of the current detector 9. When there is no output from the current detector, the output of the power converter is stopped.

The present invention will be described with reference to FIG. In the present invention, in order to detect a failure of the current detector 9, a current FB detector 10 is added to the configuration of the conventional power converter shown in FIG. When the output of the current detector 9 is input to the current FB detector 10 and the input signal is not a correct current detection waveform, the current detector 9 is determined and the power converter main circuit 2 is stopped. The power converter main circuit 2 stops immediately when the protection signal prt2 is input. The description of the same components as those in the past is omitted. By adopting such a configuration, it is possible to prevent the power converter main circuit 2 from being destroyed due to the runaway of the current controller 7 due to the fact that the output of the current detector 9 is not correctly fed back.

When the load 3 is a three-phase AC motor, the output current of the power converter main circuit is a three-phase AC current. Thus, for example, consider the case where the current detector 9 is a DC current transducer. In this case, an amplifier is built in the current detector 9, and a DC power supply voltage is required for driving. If the current detector 9 fails, the DC voltage supplied to the built-in amplifier is often output or 0V is output. Therefore, when the power converter main circuit 2 outputs the output voltage vout but the output signal of the current detector 9 is a DC signal, the current detector 9 diagnoses a failure.

The current FB detector 10 has a configuration as shown in FIG. 3, for example. The AD converter is sampled by the timer. Consider a case where the power converter main circuit 2 outputs the output voltage vout. If the change in current after a sufficiently short time Δt seconds is almost zero, the protection signal prt2 is output. The current FB detector 10 can be configured with inexpensive components when configured with electronic components. When the power converter circuit controller is equipped with a microcomputer incorporating an AD converter and a timer, if the current FB detector 10 is configured by a program, no additional parts are required.

In the present invention, although the power converter main circuit 2 outputs the output voltage vout, the output of the current detector 9 is at the same level as the DC voltage supplied to the built-in amplifier of the current detector 9. If there is, it may be detected as a failure.

The present invention relates to a protection function of a power converter, and can be applied to inverters, converters, matrix converters, and the like.

It is a figure for demonstrating the conventional power converter device. It is a figure for demonstrating the power converter device of invention. It is a figure for demonstrating the electric current FB detector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Three-phase power supply 2 Power converter main circuit 3 Load 4 Protector 5 Two-phase three-phase coordinate converter 6 Three-phase two-phase coordinate converter 7 Current controller 8 Speed controller 9 Current detector 10 Current FB detector 11 Conventional Power conversion circuit control device 12 of the invention Power conversion circuit control device of the invention

Claims (2)

There are a current command, a current detector, and a current feedback signal output from the current detector, and a current controller that performs current control by comparing the current command with the current command and the current feedback signal is provided. In a three-phase PWM inverter device, when the power converter main circuit of the three-phase PWM inverter device is in an operating state and outputs an output voltage, the output signal of the current detector becomes DC A power converter comprising: a current FB detector that determines that the current detector has failed and outputs a protection signal to the power converter main circuit. There are a current command, a current detector, and a current feedback signal output from the current detector, and a current controller that performs current control by comparing the current command with the current command and the current feedback signal is provided. In the three-phase PWM inverter device, the power detector main circuit of the three-phase PWM inverter device is in an operating state and outputs an output voltage, but the output signal of the current detector is the output of the current detector. A power converter comprising a current FB detector that determines that the current detector has failed and outputs a protection signal to the main circuit of the power converter when the supply voltage is equal to a certain time.

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