JPH10248260A - Main circuit connection judging method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To judge whether a main circuit wiring is properly connected or not by comparing the current of two phases of a current detection circuit when the voltage of one phase of a power supply phase voltage detection circuit except the two phases of the current detection circuit passes an inflexion point. SOLUTION: A power supply phase voltage detection circuit 5 and a current detection circuit 6 for two phases are provided between a capacitor-input-type rectifying circuit 2 and a three-phase AC power supply 1. Then, one switching element of the upper and lower arms of the rectifying circuit 2 is collectively turned on, and the current for two phases of the current detection circuit 6 is compared when the voltage of the other phase of a power supply phase voltage detection circuit 5 except the two phases of the current detection circuit 6 passes a inflexion point, thus determining whether a main circuit wiring is properly connected to the detection terminal of the power supply phase voltage detection circuit 5 or not, more specifically whether the main circuit wiring is connected properly or not.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a main circuit connection determination method for measuring a phase rotation direction of a three-phase PWM converter.

[0002]

2. Description of the Related Art An example of a main circuit configuration and an example of a control circuit of a three-phase sine wave PWM converter capable of making a power factor substantially equal to one by making an input current of a capacitor input type rectifier circuit into a sine wave having the same phase as a power supply phase voltage. As shown in FIG. The main circuit configuration includes a rectifier circuit 2 including a switching element such as an IGBT connected to the three-phase AC power supply 1, a capacitor 3, and a load. , An input filter 4, a power phase voltage detection circuit 5 connected to a voltage detection terminal provided on the power supply side of the input filter 4, and a two-phase current detection circuit connected to a current detector provided on the rectifier circuit side of the input filter 6. Also,
On the output side of the rectifier circuit 2, a DC voltage detection circuit 7 having a voltage detection terminal is provided.

When the gate drive circuit 8 of the rectifier circuit 2 is driven, the voltage V
_r , V _s , V _t , the current I _R ,
It refers to I _T and the DC voltage V _dc by the DC voltage detection circuit 7. That is, in consideration of the DC voltage V _dc to a set value by the DC voltage setting unit 9, and the input voltage regulator 10 is the value and the supply voltage V _r output by, V _s, and V _t to the multiplier 11, resulting The detected currents I _R and I _T are added to the output thus obtained, and the rectifier circuit 2 is supplied via the current regulator 12 and the PWM logic circuit 13.
Is controlled to obtain a desired DC voltage value.

[0004]

As can be seen from the configuration shown in FIG. 7, the detection of the power supply phase voltage is performed by the rectifier circuit 2.
This is performed on the power supply side of an input filter 4 including a reactor provided between the power supply and the three-phase AC power supply 1. in this case,
In some cases, the rectifier circuit 2 and the input filter 4 cannot be accommodated in the same case. Therefore, the user may connect the detection end of the power supply phase voltage detection circuit 5 to the user. At this time, if, for example, the main circuit wiring (RST) and the power supply phase voltage detection signal line (rst) are not connected to each other, the converter, which is a rectifier circuit, does not operate normally, and in some cases, the switching element is damaged. It also happens.

The present invention has been made in view of the above-described problems, and has been made in consideration of the above-described problem. The purpose is to provide a judgment method.

[0006]

The present invention that achieves the above object has the following matters specifying the invention. (1) In the method for determining connection of a main circuit of a three-phase PWM converter comprising a power supply phase voltage detection circuit and a two-phase current detection circuit between a capacitor input type rectifier circuit and a three-phase AC power supply, the current detection circuit When the voltage of another phase of the power supply phase voltage detection circuit excluding the two phase components passes through the inflection point, the two phase currents of the current detection circuit are compared. (2) In the main circuit connection determination method of (1), the phase rotation direction is detected from the voltage values of the remaining two phases when the voltage of the other phase passes through the inflection point, and then the rectification is performed. The circuit is energized as a diode rectifier, the inflection point is detected, the polarity of the remaining two phases is detected, and the magnitudes are compared. (3) In a main circuit connection determination method for a three-phase PWM converter including a power supply phase voltage detection circuit and a two-phase current detection circuit between a capacitor input type rectifier circuit and a three-phase AC power supply, When at least one of the switching elements of the upper arm and the lower arm is turned on collectively, and the voltage of another phase of the power supply phase voltage detection circuit excluding the two phases of the current detection circuit passes through the conversion point, The present invention is characterized in that the two currents of the current detection circuit are compared. (4) In the main circuit connection determination method of (3), the phase rotation direction is detected from the voltage values of the remaining two phases when the voltage of the other phase passes through the conversion point, and the switching element is detected. Is characterized in that the magnitudes of the current values of the remaining two phases in proportion to the phase voltage accompanying the ON for a certain time are detected and compared.

[0007] Before starting the operation In the three-phase PWM converter, to implement the measurement of the phase rotation direction due to the connection of the power supply phase voltage detection signal V _r V _s V _t of the three-phase, zero crossings of the V _s At the inflection point where the positive and negative electrodes change, the other phases r and t
It is possible to confirm whether the connection is normal or not by comparing the sizes of the two.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to FIGS. FIG. 1 shows an example of a main circuit configuration of a PWM converter. The power supply is turned on and the connection of the main circuit wiring is determined before the operation of the PWM converter is started. Incidentally, using a microcomputer is hitting the control current value I _R I _T of the power supply phase voltage value is detected V _r V _s V _t and two phases are A / D
It is designed to be captured using a converter.

In FIG. 1, when detecting the power supply phase voltage via a disconnected transformer, first, the rotation direction of the power supply phase voltage is measured. That is, three phases of the voltage detection signal V _r, V _s, the V _t, firstly, detects a detection level positive mode changes 0 cross point from negative as shown in Figure 2 of the detection signal V _s (inflection point) I do. Then, the signal V _s is 0 at the cross state of the other two phases of the detection signals V _r, measured V _t, performs the following determination. That is, it is determined and the phase rotation direction normal at _{(a) V r> V t} ( FIG. 2 (a)) (b) V r < a phase rotation direction opposite at V _t (Figure 2 (b)).

Next, the normal / abnormal judgment of the main circuit wiring is performed. In order to operate a load connected to the DC side, for example, a motor drive inverter, a current simply flowing as a diode rectifier flows through the main circuit. Next, the control waits for a zero cross point at which the detection level of the power supply phase voltage detection signal V _s (a phase in which current detection is not performed) switches from negative to positive. When detecting the current IRIT the R-phase and T-phase at the zero cross state of the detection signal V _s, the phase rotation of the power supply phase voltage detection signal measured before the positive _{(V r> V t),} IR>IR> 0 and IT at IT
If <0, the connection is determined to be normal. Otherwise, the connection is determined to be abnormal.

In the zero cross state, the R phase and the T
Result of detection of the current phase, if the phase rotation of the power supply phase voltage detection signal measured before the reverse (V _r <V _t), determines that the normal connection by IR <0 and IT> 0 in IR <IT Otherwise, it is determined that the connection is abnormal.

The above-mentioned use state is a capacitor input type diode rectifier circuit, and the AC input current waveform I
R, IT and the phase voltage V _s, V _r, the relationship between V _t, a waveform shown if Figure 3 phase rotation direction is positive, the waveform shown if Figure 4 phase rotation direction is reversed. As a result, when the phase voltage of the S phase to which the current detector is not connected is in a zero cross state from negative to positive, no current flows in the S phase, and the R and T phases have the same absolute value and the sign Different currents will flow.
For this reason, if the phase rotation direction of the power supply phase voltage detection signal has been confirmed, the magnitude comparison including the currents IR and IT is performed.
The connection state of the power supply to the main circuit wiring can be determined.

Next, another determination method will be described with reference to FIGS. Wait for positive switched point from negative at the zero cross point of the power supply phase voltage V _s is performed similar to that described above phase rotation detection. And
In this zero cross state, the switching element lower arms SX, SY, SZ (upper arms SU, SZ) of the rectifier circuit 2 in FIG.
V or SW) may be turned on for the time of _TZO described later.
After a lapse of time T _ZO , the currents IR and I of the R phase and the T phase
T detection is performed, and the following determination is made. That is, when the phase rotation direction of the power supply phase voltage detection signal is positive, IR> IT and I
If R> 0 and IT <0, it is determined that the connection is normal. Otherwise, it is determined that the connection is abnormal. ,
Otherwise, it is determined that the connection is abnormal.

When the phase voltage of the S phase to which the current detector is not connected is in a zero-cross state from negative to positive, if the peak value of the phase voltage is V _p , the phase voltage of the R phase is √3 / 2.・ V _p ,
Phase voltage of T-phase becomes -√3 / 2 · V _p (Figure 5). Therefore, turning on the three lower arms or the three upper arms during the period of T _zo means that the power supply is short-circuited through the reactor (FIG. 6), and the phase currents after the elapse of the T _zo time are shown. Is, if the inductance of the reactor is L, IR ≒ ({3/2 · V _p ) / L · T _zo , IT ≒ −
(√3 / 2 · V _p ) / L · T _zo , and the current value becomes a value proportional to the magnitude of the phase voltage. Therefore, by measuring the current value, it is possible to determine the connection state of the power supply to the main circuit wiring.

Here, the on time T _zo of the switching element is
Is described. Normally, the absolute value of the inductance L [H] of the reactor of the PWM converter differs according to the applicable device capacity, but it is determined that the absolute value of the inductance L [H] becomes the same value for all the device capacities when expressed in percent impedance with respect to the device capacity. I have. Therefore, when this reactor is expressed by percent impedance, and the current value after the elapse of the _Tzo time is expressed by percent impedance, the following equation is obtained.

[0016]

(Equation 1) Here, the current value for confirmation (| IR | = | IT | , the peak value) by the following equation when obtaining the T _zo for the to approximately 10% of the peak value of the rated current [Number 2] Become.

[0017]

(Equation 2) As a result,% Z = 10% f = the 55H _Z T _zo ≒ 33.4
μs.

[0018]

According to the present invention, in a three-phase sine wave PWM converter in which the input current of the capacitor input type rectifier circuit has a sinusoidal waveform having the same phase as the power supply phase voltage and the power factor can be made substantially 1, the power supply phase voltage detection signal is obtained before the operation is started. It is possible to determine whether the connection of the line and the connection of the main circuit wiring are normally performed, and it is possible to prevent abnormal operation of the PWM converter and damage to the switching element.

[Brief description of the drawings]

FIG. 1 is a connection diagram of a main circuit configuration of a PWM converter.

FIG. 2 is a waveform diagram for explaining measurement of power supply phase voltage phase rotation.

FIG. 3 is a waveform diagram of a phase rotation direction “positive”.

FIG. 4 is a waveform diagram of a “reverse” phase rotation direction.

[5] the phase voltage waveform diagram of V _s zero crossing for explanation of another example.

FIG. 6 is an equivalent circuit diagram in which a lower or upper arm is short-circuited.

FIG. 7 is an overall circuit diagram.

[Explanation of symbols]

 1 Three-phase AC power supply 2 Rectifier circuit 5 Power supply phase voltage detection circuit 6 Current detection circuit

Claims (4)

[Claims] 1. A main circuit connection determination method for a three-phase PWM converter comprising a power supply phase voltage detection circuit and a two-phase current detection circuit between a capacitor input type rectifier circuit and a three-phase AC power supply. When the voltage of another phase of the power supply phase voltage detection circuit except for the two phases of the detection circuit passes through the inflection point, the current of the two phases of the current detection circuit is compared. Main circuit connection determination method. 2. The main circuit connection determination method according to claim 1, wherein the phase rotation direction is detected based on the voltage values of the remaining two phases when the voltage of the other phase passes through the inflection point. A main circuit connection judging method characterized in that the rectifier circuit is energized as a diode rectifier, the inflection point is detected, the sign of the current value of the remaining two phases is detected, and the magnitude is compared. 3. The main circuit connection determination method for a three-phase PWM converter comprising a power supply phase voltage detection circuit and a two-phase current detection circuit between a capacitor input type rectifier circuit and a three-phase AC power supply. The switching elements of at least one of the upper arm and the lower arm of the circuit are turned on collectively, and the voltage of another phase of the power supply phase voltage detection circuit excluding the two phases of the current detection circuit passes through the conversion point. A main circuit connection determination method, wherein the two currents of the current detection circuit are compared. 4. The main circuit connection determination method according to claim 3, wherein a phase rotation direction is detected based on a voltage value of the remaining two phases when the voltage of the other phase passes through the conversion point, A main circuit connection judging method characterized by detecting whether the current values of the remaining two phases in proportion to the phase voltage when the switching element is turned on for a predetermined time are positive or negative, and comparing the magnitudes.