JP4079201B2 - Inverter test equipment - Google Patents

Description

  The present invention relates to an inverter test apparatus for testing an inverter having a motor as a load.

FIG. 7 is a circuit configuration diagram showing an example of a conventional inverter test apparatus using a motor as a load.
In FIG. 7, a pseudo load circuit 200 composed of a plurality of resistors R, inductances L and switches is connected to the U-phase, V-phase, and W-phase of the AC output terminal of the inverter 100 under test. A motor angle sensor 300 is provided.

Next, the operation will be described.
In general, inverter control methods are roughly classified into a current control method using a current control loop and a voltage control method (V / F control or the like) having no current control loop.
In the case of the current control method, with respect to the angle θm (phase) indicating the position of the motor rotor detected by the angle sensor 300, the inverter under test is set so that a predetermined current of amplitude ic flows at an angle θm + θc corresponding to the operating condition. 100 is controlled. At this time, by switching the switches of each pseudo load circuit 200 so that the angle (phase with respect to the current) and the amplitude of the output voltage of the inverter under test 100 are equivalent to those during operation of the motor that is the actual load, R and L are changed. select.
As the angle sensor 300, for example, a resolver, an encoder or the like is used, and the angle sensor 300 is rotated by using a small motor (not shown) of about several watts so that the angle θm can be obtained. Thus, a simulated angle sensor signal Sθ corresponding to θm is generated.

  In the case of the voltage control method, a voltage having an angular velocity (output frequency) and an amplitude corresponding to the operating condition is output from the inverter under test 100. At this time, R and L are selected by switching the switches of each pseudo load circuit 200 so that the angle (phase with respect to voltage) and the amplitude of the output current of the inverter under test 100 are equivalent to those during operation of the motor. In the case of the voltage control method, the angle sensor 300 is omitted.

  As described above, heat and voltage / current waveforms are checked by performing tests while switching RL so that the amplitude, phase, power factor, and torque of the voltage / current according to the motor operating conditions can be obtained. Then, the inverter under test 100 is evaluated.

However, in the conventional inverter test apparatus,
1. A test in the power running operation of the motor is performed, but a test in the regenerative operation is impossible. 2. To make it possible to cope with various operation conditions in the power running operation, R, L constituting the pseudo load circuit 200 , It is necessary to increase the number of switches, which complicates the configuration, increases the size of the device including the weight, and increases the cost.
3. All power during the test becomes heat and is wasted.
4. Since R and L are selected according to the steady state characteristics, the transient characteristics cannot be made the same as during motor operation.
5. In the case of the current control method, in order to generate the simulated angle sensor signal Sθ from the angle sensor 300, another means such as a small motor for rotating the angle sensor 300 must be prepared.
And so on.

  In order to solve the above-described problem, the present invention uses two power converters, and uses one power converter as a virtual load of the output of the motor to simulate the operation of the motor without actually connecting to the motor. The purpose of this is to test the inverter.

  In order to achieve the above object, an inverter testing apparatus according to the present invention is provided between a second inverter serving as a pseudo load of a first inverter to be tested, an AC power source, and a first inverter. A first power converter that supplies DC power to one inverter; a second power converter that is provided between the AC power supply and the second inverter and supplies DC power to the second inverter; and the AC A transformer that insulates between at least one of the power source and the output of the first inverter or between the AC power source and the output of the second inverter; and an actual load of the first inverter. The output current of the first inverter is controlled to a predetermined value in accordance with the motor rotation speed set for a certain motor, and the motor rotation speed, the motor constant, and the detected output voltage / current of the first inverter are determined. Or a control means for controlling the amplitude and phase of the output voltage of the second inverter based on the both, the second inverter is composed of three single-phase inverters, and the single-phase inverter The second power converter is provided for each phase and is connected to the single-phase inverter one by one.

Note that “between the AC power supply and the output of the first inverter” means that it may be provided anywhere between the AC power supply and the output of the first inverter. It may be provided adjacent to the AC power source, the first power converter or the first inverter, or may be provided in the first power converter or the first inverter.
Similarly, “between the AC power supply and the output of the second inverter” means that it may be provided anywhere between the AC power supply and the output of the second inverter. For example, it may be provided adjacent to the AC power supply, the second power converter or the second inverter, or may be provided in the second power converter or the second inverter. .

  The inverter test apparatus according to the present invention is characterized in that the first and second power converters are AC / DC converters having a function of performing power regeneration.

  In the inverter testing apparatus according to the present invention, one of the first and second power converters is an AC / DC converter having a function of performing power regeneration, and the other is a rectifier using a diode. Features.

  In the inverter testing apparatus according to the present invention, rectifying means is provided between the AC power source and the second power converter, and the second power converter is an insulated bidirectional DC / DC converter. It is characterized by being.

  In the inverter testing apparatus according to the present invention, the control means controls the output current of the first inverter to a predetermined value according to the motor rotational speed included in the operating condition, and the motor rotational speed and the motor characteristics. The amplitude and phase of the output voltage of the second inverter are controlled in a predetermined manner on the basis of the motor constant included in and the detected output voltage and current of the first inverter.

  In the inverter testing apparatus according to the present invention, the motor constant includes a value of each component of the motor equivalent circuit, and the control means performs control based on a predetermined voltage conversion formula using the motor constant. Features.

  In the inverter testing apparatus according to the present invention, the control means calculates a motor torque from the output voltage / current of the first inverter and a motor characteristic, and the motor is calculated from the torque and a mechanical constant included in the motor characteristic. It is characterized by simulating the operation at the time of acceleration / deceleration of the motor by sequentially calculating the speed and angle and using them for control.

  Further, in the inverter testing apparatus according to the present invention, the outputs of the first and second inverters are PWM signals, and the motor is connected between the AC output of the first inverter and the AC output of the second inverter. A first filter having an inductance corresponding to the inductance is provided, and a second filter for extracting a fundamental wave from the output of the second inverter is provided between the AC output of the second inverter and the first filter. It is characterized by that.

  The inverter testing apparatus according to the present invention calculates and displays all or any of the torque, speed, rotational position, loss, efficiency, temperature, etc. of the motor from the output voltage / current of the first inverter and the motor constant. Or output.

  Therefore, according to the present invention, the rotational speed of the motor and the motor constant are set in the control means, and the output current / voltage of the first inverter is detected, and the control means detects the first inverter according to the motor rotational speed. The output current of the inverter is controlled to a predetermined value, and the actual motor is connected by controlling the amplitude and phase of the output voltage of the second inverter based on the motor speed, motor constant and output current / voltage. In addition, it is possible to simulate the same operating state as when the motor is connected.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a circuit diagram showing an inverter test apparatus according to a first reference example of the present invention.
This test apparatus is based on a current control method when an IPM motor (embedded magnet type synchronous motor) is assumed as an actual load. As shown in the drawing, the test apparatus is connected to an inverter under test 1 (hereinafter referred to as an inverter 1). On the other hand, a pseudo load inverter 2 (hereinafter referred to as an inverter 2) is used. As the inverters 1 and 2, voltage (source) type inverters that are advantageous for downsizing are used.

  In FIG. 1, a three-phase AC voltage from a commercial AC power source 3 is converted into a DC voltage by a rectifier circuit 5 via a transformer 4, adjusted by a chopper circuit 6 for adjusting a test voltage, and then supplied to the inverter 1. . The DC voltage is also supplied to the inverter 2. From the AC output terminal of the inverter 1, a PWM1 signal is output as a PWM-modulated rectangular wave voltage. This PWM1 signal is converted into a sine wave by a filter 7 having an inductance L and applied to the primary side of the transformer 8. From the AC output terminal of the inverter 2, a PWM2 signal is output as a PWM-modulated rectangular wave voltage. From this PWM2 signal, a sine wave of a fundamental wave is taken out through a filter 9 including an inductance l, a capacitor c, and a resistor r, and is applied to the secondary side of the transformer 8. The inductance L in the filter 7 corresponds to the inductance of the motor as a load.

  The U-phase and W-phase currents iu and iw (controlled to a predetermined value by the current control method) of the PWM1 signal output from the inverter 1 are detected by the current transformer 10 and sent to the motor simulation operation control unit 11. Added. Also, sinusoidal voltages vu 'and vw' obtained from the PWM1 signal through the filter 7 are detected and applied to the motor simulation operation control unit 11.

  The motor simulation operation control unit 11 is input and set with motor operating conditions and motor characteristics as a load. The operating conditions include a desired motor speed N, torque (load), control mode, and the like. Motor characteristics include motor constants and voltage / current equations. The motor constant is each component of the motor equivalent circuit. The motor constants in the case of an IPM motor include the motor armature resistance R, the motor inductance Ld on the d axis on the d and q orthogonal coordinate axes on the motor stator, the motor inductance Lq on the q axis, and the motor induced voltage constant φa. And the inductance L of the filter 7 is input. The motor simulation operation control unit 11 is provided with an angle sensor simulation control unit 12.

  Next, the principle of the inverter 1 will be described. When the inverter 1 and the inverter 2 are considered as two AC voltage sources connected via impedance, the impedance viewed from the inverter 1 varies depending on the relationship between the output voltages of the inverters 1 and 2. This impedance corresponds to the load impedance of the motor. For example, if each output voltage is in phase, the load impedance of the inverter 1 becomes a resistance component according to the amplitude of each output voltage. Further, if the output voltage of the inverter 2 is controlled so that the current is delayed by 90 ° with respect to the phase of the output voltage of the inverter 1, the load impedance becomes an inductance component. That is, by controlling the amplitude and phase of the output voltage of the inverter 2 with respect to the output voltage of the inverter 1, the load impedance becomes variable.

  Therefore, according to this reference example, by controlling the amplitude and phase of the output voltage of the inverter 2 as an addition to the proceedings, the motor as the actual load can be put in a simulated operation state. Thereby, the test of the inverter 1 in an arbitrary load can be performed under an arbitrary operation condition.

  Next, an actual test operation will be described. When testing the inverter 1 by the current control method, the output currents iu and iw of the inverter 1 are controlled to predetermined values regardless of the output voltage of the inverter 2. The illustrated inverter 1 includes a control circuit for performing current control. In the motor simulation operation control unit 11, the above-described operation conditions N and motor constants R, Ld, Lq, L, and φa are input and set by the operator. The angle sensor simulation control unit 12 outputs a simulation angle sensor signal Sθ corresponding to N, and the inverter 1 controls the output current to a predetermined value based on the simulation angle sensor signal Sθ.

  Further, the motor simulation operation control unit 1 generates and outputs a gate signal for switching the inverter 2 based on the operation condition N and motor constants R, Ld, Lq, L, and φa, and the inverter 2 responds to the gate signal. Works. That is, the inverter 2 is controlled to have the voltage / current amplitude / phase according to the operation of the inverter 1. The motor simulation operation control unit 11 performs control while observing the output currents iu and iw and the output voltages vu 'and vw' of the inverter 1. The amplitude and phase of the output voltages vu 'and vw' are determined by the load.

  That is, whether the motor is connected to the inverter 1 by controlling the amplitude / phase of the output voltage of the inverter 2 so that the amplitude / phase of the output voltage becomes desired when the output current of the inverter 1 is constant. In this state, the inverter 1 can be tested. As described above, the inverter 1 can be tested by setting an arbitrary power factor and load impedance according to an arbitrary operating condition of the motor.

  Next, in this reference example, by providing a transformer 8 between the inverter 1 and the inverter 2 and galvanically insulating them, the influence of the neutral point fluctuation of the three-phase output voltage of the inverter 1 is eliminated. Good control is performed. That is, in the inverter, as shown in FIG. 2A, the neutral point voltage is varied at a predetermined timing by the neutral point voltage fluctuation circuit 15 in order to widen the range of the output voltage (line voltage). There is. In this case, if the load is a motor, no matter how the neutral point voltage fluctuates, there is no effect on the motor. However, if the load is an inverter 2 as shown in FIG. When the neutral point voltage is varied by the fluctuation circuits 15 and 16, a current ix unrelated to the actual motor current flows between the inverter 1 and the inverter 2 due to the influence. It is difficult to control this current ix to zero. Therefore, in the present embodiment, the current ix is cut off by providing the transformer 8.

  Next, since the output voltages of the inverters 1 and 2 are PWM waveforms, and it is difficult to detect the amplitude and phase of the fundamental wave voltage of the inverter 1 without delay, the PWM waveforms are made sinusoidal by the filters 7 and 9. The primary side voltages vu ', vw' of the transformer 8 are detected. Based on this voltage and the currents iu and iw, the output voltage vu of the inverter 1 is calculated by the following equation. vu = L ・ iu + vu ′ ──── （1）

  If the load is an IPM motor,

  Control is performed so as to satisfy the voltage equation. In equation (2), Vd, Vq: d, q-axis armature voltage, id, iq: d, q-axis armature current, R: armature resistance, Ld, Lq: d, q-axis inductance, ωm: Angular velocity (corresponding to N), p: d / dt, φa: maximum value of armature flux linkage by permanent magnet × (square root of 3/2), pn: number of pole pairs. T is an output torque, and T = [pn {φa iq + (Ld−Lq) id iq}] (3).

  FIG. 3 shows the motor simulation operation control unit 11 when the voltage conversion equation according to the above equation (2) is realized by a hardware configuration. An adder, a multiplier, a correction circuit, a differentiation circuit, a 2/3 circuit (three-phase circuit) -Phase conversion circuit), PWM circuit 13 and the like. Note that pLd and pLq in equation (2) are excessive terms and are small in actual operation, and are ignored in this embodiment.

  In FIG. 3, the input R, Ld, Lq, θm (angle corresponding to the simulated angle sensor signal Sθ: corresponding to N), φa, L, and voltages vu ′, vw ′, currents iu, iw are illustrated. Each calculation is performed. Thereby, phase voltage commands Vou *, Vov * and Vow * are generated, and the gate signal of the inverter 2 is generated from the PWM circuit 13 based on the phase voltage commands Vou *, Vov * and Vow *.

  In FIG. 3, iu and iw are subjected to three-phase to two-phase conversion based on the value obtained by correcting the angle of θm to obtain id and iq on two orthogonal axes, and vu ′ and vw ′ are set to values obtained by correcting the angle of θm. Based on the three-phase to two-phase conversion, vd and vq are obtained. Further, the difference between Ld and Lq and the actual L is obtained, and vd * and vq * are obtained based on this difference and R, id and iq. Vou *, Vov * and Vow * are obtained by matching the vd * and vq * with the actual vd and vq and subjecting the result to a two-phase to three-phase conversion based on the angle corrected value of θm.

  Next, a second reference example of the present embodiment will be described. In the first reference example described above, control is performed by setting the motor rotational speed N (θm) in advance. However, without setting N, the motor torque is calculated from the output current / voltage of the inverter 1, By calculating N (θm) from the torque (equivalent to weight or the like) of the machine assumed in the test and using it for control, it is possible to simulate the motor acceleration / deceleration state. That is, when the inverter 1 operates and accelerates from a state where the motor is stopped, how it accelerates depends on what pattern the current / voltage is applied to.

  For example, in the case of a motor that drives an electric vehicle, the motor simulation operation control unit 11 can calculate whether or not the torque is generated by the input output voltage / current (vu ′, vw ′, iu, iw). If the inertia in terms of the motor shaft is known from the weight of the vehicle body or the like, how to accelerate according to the torque can be calculated in consideration of the running resistance and the like.

  That is, from the calculated torque, inertia, running resistance, etc., how much the speed N is to be accelerated and then how many the speed N is to be calculated is calculated. Based on the N, the simulated angle sensor signal is calculated. By making Sθ and feeding it back to the inverter 1, various tests can be performed while the motor is actually accelerating / decelerating. Therefore, in the present embodiment, the motor simulation operation control unit 11 is input and set with mechanical constants such as the vehicle weight, inertia, running resistance, and the like.

  In addition, although each reference example mentioned above demonstrated the case where an IPM motor was used as a load, if there is a voltage equation, any motor, such as an IM motor (induction motor) and an SPM (surface magnet synchronous) motor, can be simulated. It is.

  As a third reference example, as shown in FIG. 1, in the motor simulation operation control unit 1, the motor torque, speed, rotational position, loss efficiency, temperature, etc. are calculated from the output voltage / current of the inverter 1 and the motor constant. It may be configured to calculate and display or output.

  Next, first to third embodiments of the present invention will be described. In the first reference example of FIG. 1 described above, a transformer 8 is inserted between the inverter 1 and the inverter 2 to insulate them. For this reason, if the test is performed by operating the inverter 1 at a frequency close to DC and simulating the state of the low-speed operation of the motor, the transformer 8 is saturated and the control of the inverter 2 as a pseudo load becomes impossible. Occurs.

  When the inverter 1 is operated with direct current and the motor is stopped and the test is performed, the inverter 2 side of the transformer 8 is short-circuited (all the switching elements on the lower side or upper side of each phase of the inverter 2 are all connected). In this case, the saturation of the transformer 8 is not a problem, but even if the inverter 2 is controlled, it is not equivalent to the operation of the motor and is inserted as a characteristic. There arises a problem that it is determined by the inductance and resistance of the transformer 8 and the line.

  As described above, when the simulated operation of the motor is performed from the regenerative operation to the power running operation, there is a problem that the transformer 8 becomes larger and the cost is increased in order to make the transformer 8 usable from a direct current to a high frequency. Arise.

  Therefore, the first to third embodiments are for solving the above-described problem, and the inverter 1 and the inverter 2 are insulated by using means in place of the transformer 8.

FIG. 4 shows a first embodiment.
In FIG. 4, parts corresponding to those in FIG.
FIG. 4 shows the basic configuration in a simplified manner. The inverters 1 and 2 in FIG. 1 indicate three phases with ///, and the motor simulation operation control unit 11 and related parts are not shown. It is omitted.
In FIG. 4, a regenerative converter (sine wave converter) 21 as an AC / DC converter is connected to the input side of the inverter 1 through a chopper 6 and a capacitor C1, and the input side of the inverter 2 is connected to an AC through a capacitor C2. A regenerative converter 22 as a DC converter is connected.

  A three-phase AC voltage from the commercial AC power source 3 is applied to the regenerative converter 21 through the transformer 4 and the inductance 23, and a DC (direct current) voltage obtained at the capacitor C 1 is adjusted by the chopper circuit 6 and then supplied to the inverter 1. Is done. In addition, a three-phase AC voltage from the commercial AC power source 3 is applied to the regenerative converter 22 through the transformer 4, the transformer 20, and the inductance 24, and a DC voltage obtained at the capacitor C2 is supplied to the inverter 2.

  Although the transformer 20 is connected to the secondary side of the transformer 4 in the drawing, it may be directly connected to the commercial AC power source 3 as indicated by a dotted line. Further, the transformer 4 is not always necessary. Moreover, although the filter 9 of FIG. 1 is abbreviate | omitting illustration, it is provided as needed.

  As described above, in the present embodiment, the transformer 20 is used in place of the insulating transformer 8 of FIG. 1, and the inverter 1 and the inverter 2 are separated on the AC power source side by the transformer 20 so as to be galvanically insulated. I have to. Thereby, it is possible to prevent the current ix from flowing due to the neutral point fluctuation in the inverters 1 and 2 described in FIG. Moreover, since the transformer 20 is used by being fixed at the frequency of the commercial AC power supply 3, a small-sized transformer can be used. The regenerative converters 21 and 22 are provided to supply a direct current (DC) voltage to the inverters 1 and 2. That is, the regenerative converters 21 and 22 perform AC / DC conversion on the input AC voltage and store it in the capacitors C1 and C2.

Next, the operation will be described.
When simulating the power running operation of the motor, the regenerative converter 21 is controlled to generate a voltage whose amplitude is larger than that of the AC power supply voltage and whose phase is delayed. In-phase current flows, energy is stored in the capacitor C 1, and is supplied to the inverter 1 through the chopper 6. That is, the inverter 1 is supplied with energy from the AC power source. On the other hand, the inverter 2 stores the energy supplied from the inverter 1 in the capacitor C2, and also controls the regenerative converter 22 to generate a voltage having a larger amplitude and a more advanced phase than the AC power supply voltage. , A current having a phase opposite to that of the AC voltage applied to the inductance 24 flows, and this current is returned to the AC power source through the transformer 20.

  When simulating the regenerative operation of the motor, the regenerative converter 21 generates a voltage whose amplitude is larger than that of the AC power supply voltage and whose phase is advanced in reverse to the above, so that a current opposite to the AC voltage applied to the inductance 23 is generated. Flowing. Further, the inverter 2 stores the energy from the regenerative converter 22 in the capacitor C2, and supplies it to the inverter 1 from the inverter 2.

  In the above description, the case where the regenerative converters 21 and 22 are provided as AC / DC converters on the inverters 1 and 2 side has been described, but instead of the regenerative converter 21 or 22, a diode bridge equivalent to the rectifier circuit 5 of FIG. The made diode rectifier may be used as an AC / DC converter. In this case, when a diode rectifier is used instead of the regenerative converter 21, it is effective only when the inverter 1 performs a power running operation. In addition, when a diode rectifier is used instead of the regenerative converter 22, it is effective only when the inverter 1 performs a regenerative operation. And when using the regenerative converters 21 and 22 like FIG. 4, it is effective when the inverter 1 performs power running / regenerative operation.

Next, a second embodiment will be described with reference to FIG.
In FIG. 5, parts corresponding to those in FIGS. 4 and 1 are denoted by the same reference numerals. The present embodiment is a modification of the above-described fourth embodiment, and is a case where the inverter 2 is composed of three single-phase inverters 2a and the regenerative converter 22 is connected to each single-phase inverter 2a. In this case, control is performed so that the same operation as that of the three-phase inverter 2 is performed by the three single-phase inverters 2a.

  According to the present embodiment, the degree of freedom of the output voltage is higher than that of a three-phase inverter in which the DC portion is common to each phase, and control of the unbalanced voltage of the inverter 1 is also possible. In place of the regenerative converter 21 or 22, a diode rectifier may be used.

  Next, a third embodiment will be described with reference to FIG. In FIG. 6, parts corresponding to those in FIGS. 4 and 1 are denoted by the same reference numerals. In this embodiment, an insulating bidirectional DC / DC converter 25 is provided between the rectifier 5 and the inverter 2 as shown in the figure, and the inverters 1 and 2 are insulated. The insulated bidirectional DC / DC converter 25 includes a single-phase inverter 26, a transformer 27, and a single-phase inverter 28.

  According to the above configuration, the flow of energy can be controlled bidirectionally by controlling the amplitude and phase of the AC output of the single-phase inverters 26 and 28. According to the present embodiment, the inverters 1 and 2 can be insulated from each other by the transformer 27 of the insulation type bidirectional DC / DC converter 25.

  As described above, according to the present invention, the inverter can be tested while simulating the operation of the motor without actually using the motor. In addition, a regenerative operation test that cannot be performed by switching the conventional RL load can be performed. In addition, the energy saving of the apparatus can be greatly reduced as compared with the case of switching the RL load. Furthermore, in the case of current control, the voltage and power factor of the inverter under test can be adjusted.

  Further, by providing a transformer between the inverter under test and the pseudo load inverter, it is possible to eliminate the influence due to the fluctuation of the neutral point voltage in the inverter under test and perform good control. Moreover, in order to insulate between the inverter under test and the inverter for pseudo load, by providing a regenerative converter, a diode rectifier, and an insulation type bidirectional DC / DC converter, the influence due to the fluctuation of the neutral point voltage is eliminated, In addition to being able to perform good control, it is possible to perform a test from a direct current to a high frequency, that is, a motor simulation test regardless of the frequency from the stop of the motor to high-speed rotation.

FIG. 5 shows an example in which the outputs of the three isolated single-phase inverters 2a are delta-connected to form a three-phase AC power source, that is, an inverter. Needless to say, the output of the phase inverter 2a may be star-connected to form a three-phase AC power source.
In addition, a normal inverter that connects three bridges to a DC power source and constitutes a three-phase AC with the middle of the upper and lower switches of each bridge as an output, each bridge operates as a variable DC power source. Specifically, it can be said that a three-phase AC power source is configured by connecting, for example, the minus side of a variable DC power source and outputting three plus sides.
Therefore, when a three-phase AC power source is configured by star-connecting the outputs of the three single-phase inverters 2a, one of the two bridges (switches connected in series above and below) of each single-phase inverter 2a. A single-phase inverter that operates as a DC power supply by turning on or turning off the upper or lower switch at the same time and simultaneously turning on and off the upper and lower switches of the other bridge. It is obvious that even if a three-phase AC power supply is configured, the function similar to that of the inverter is obtained due to the magnitude relationship of the output voltages.

  In the case of star connection, each DC power supply may or may not be insulated. That is, in the case where an inverter is configured by three single-phase inverters 2a connected in a star connection, the output voltage V1 of the first single-phase inverter operated as a DC power source and the second operated as a DC power source. Even if each output voltage V2 of the single-phase inverter is a positive voltage (when the switch under one of the bridges is always turned on in the above description), if control is performed so that V1 <V2, 1 Seen from the output of the first single-phase inverter, the output of the second single-phase inverter is positive, while if the control is performed so that V1> V2, the output of the first single-phase inverter is The output of the second single-phase inverter is negative. As a result, it is clear that the voltage between the output of the first single-phase inverter and the output of the second single-phase inverter can be alternating.

It is a circuit block diagram which shows the inverter test apparatus of the current control system by the 1st Embodiment of this invention. It is a block diagram for demonstrating the reason which provided the trans | transformer 8 in FIG. It is a block diagram which shows the hardware structural example of the motor simulation operation control part in an electric current control system. It is a circuit block diagram which shows the inverter test apparatus of the current control system by the 4th Embodiment of this invention. It is a circuit block diagram which shows the inverter test apparatus of the current control system by the 5th Embodiment of this invention. It is a circuit block diagram which shows the inverter test apparatus of the current control system by the 6th Embodiment of this invention. It is a block diagram which shows an example of the conventional inverter test apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inverter to be tested 2 Inverter for pseudo load 7 Filter 8 Transformer 9 Filter 10 Current transformer 11 Motor simulation operation control unit 12 Angle sensor simulation control unit 13 PWM circuit 20 Transformer 21, 22 Regenerative converter (AC / DC converter)
23, 24 Inductance 2a Single-phase inverter 25 Insulated bi-directional DC / DC converter

Claims (9)

A second inverter serving as a pseudo load for the first inverter under test;
A first power converter provided between the AC power source and the first inverter and supplying DC power to the first inverter;
A second power converter provided between the AC power source and the second inverter and supplying DC power to the second inverter;
A transformer that insulates between at least one of the AC power supply and the output of the first inverter or between the AC power supply and the output of the second inverter;
The output current of the first inverter is controlled to a predetermined value according to the set motor speed of the motor that is the actual load of the first inverter, and the motor speed and the motor constant are detected and the first inverter detected Control means for controlling the amplitude and phase of the output voltage of the second inverter in a predetermined manner based on either or both of the output voltage and current of
The second inverter is composed of three single-phase inverters, and the single-phase inverter is provided for each phase,
The said 2nd power converter is connected to the said single phase inverter 1 each. The inverter test apparatus characterized by the above-mentioned.   The inverter test apparatus according to claim 1, wherein the first and second power converters are AC / DC converters having a function of performing power regeneration.   2. The inverter test according to claim 1, wherein one of the first and second power converters is an AC / DC converter having a function of performing power regeneration, and the other is a rectifier using a diode. apparatus. Rectifying means is provided between the AC power source and the second power converter,
The inverter test apparatus according to claim 1, wherein the second power converter is an insulated bidirectional DC / DC converter.   The control means controls the output current of the first inverter to a predetermined value according to the motor rotational speed included in the operating condition, and also detects the motor rotational speed, the motor constant included in the motor characteristics, and the detected The inverter testing apparatus according to any one of claims 1 to 4, wherein the amplitude and phase of the output voltage of the second inverter are controlled to be predetermined based on the output voltage and current of the first inverter.   6. The motor constant according to claim 1, wherein the motor constant includes a value of each component of a motor equivalent circuit, and the control means performs control based on a predetermined voltage conversion formula using the motor constant. The inverter test apparatus according to claim 1.   The control means calculates motor torque from the output voltage / current of the first inverter and motor characteristics, and sequentially calculates motor speed and angle from the torque and mechanical constants included in the motor characteristics for control. The inverter test apparatus according to claim 1, wherein the inverter test apparatus simulates an operation during acceleration / deceleration of the motor.   The outputs of the first and second inverters are PWM signals, and the first inverter having an inductance corresponding to the inductance of the motor is provided between the AC output of the first inverter and the AC output of the second inverter. 2. A filter is provided, and a second filter that extracts a fundamental wave from the output of the second inverter is provided between the AC output of the second inverter and the first filter. The inverter test apparatus according to any one of 7 above.   The motor torque, speed, rotational position, loss, efficiency, temperature, etc. are calculated from the output voltage / current of the first inverter and a motor constant, and are displayed or output. The inverter test apparatus according to any one of 1 to 8.

Images