Test Equipment

Abstract

To perform a test operation of a power conversion device under desired conditions.SOLUTION: A test device 10 comprises a step-up chopper circuit 40, an inverter circuit 50, a three-phase reactor 60, an inverter circuit 70, a step-down chopper circuit 80, feedback paths 91 and 92, and a control circuit 100. The step-up chopper circuit 40 is connected with the inverter circuit 50. The inverter circuit 50 is connected with the three-phase reactor 60. The three-phase reactor 60 is connected with the inverter circuit 70. The inverter circuit 70 is connected with the step-down chopper circuit 80. The feedback paths 91 and 92 connect output terminals of the step-down chopper circuit 80 with an input side of the step-up chopper circuit 40. The control circuit 100 controls the operation of the step-down chopper circuit 80 so as to reduce the difference between the value Ip of first feedback current flowing in the feedback path 91 and the value In of second feedback current flowing in the feedback path 92.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a test device for a power converter used when supplying power to an AC load. [Background technology]

[0002] A test system for a power conversion device is described in Patent Document 1. The test system described in Patent Document 1 includes an inverter to be tested, an AC reactor of a test facility, an AC-DC conversion circuit, and a DC reactor.

[0003] The AC reactor of the test equipment is connected between the DC-AC conversion circuit and the AC-DC conversion circuit. The DC side of the DC-AC conversion circuit and the DC side of the AC-DC conversion circuit are connected via the DC reactor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-145909 A Summary of the Invention [Problem to be solved by the invention]

[0005] The test system described in Patent Document 1 is capable of testing an inverter. However, in recent years, particularly in in-vehicle systems, a configuration in which a boost chopper circuit is connected in front of the inverter has become common, and the test system described in Patent Document 1 is unable to test a system including the boost chopper circuit.

[0006] More specifically, even if the boost chopper circuit is tested alone and the inverter is tested alone using the test system described in Patent Document 1, there is a problem in that the performance of the combined system, particularly with regard to noise, cannot be evaluated. Therefore, there has been a demand for a device that can perform testing while the boost chopper circuit and input side inverter circuit are connected.

[0007] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a test device capable of testing a power conversion device including a boost chopper circuit and an input side inverter circuit under desired conditions. [Means for solving the problem]

[0008] A test device according to one aspect of the present invention includes a boost chopper circuit, a first three-phase inverter circuit, a three-phase reactor, a second three-phase inverter circuit, a step-down chopper circuit, a first feedback path, a second feedback path, a control circuit, and a test instrument. The boost chopper circuit has a pair of a first input terminal and a second input terminal, and outputs a first DC voltage. The first three-phase inverter circuit generates a three-phase AC voltage from the first DC voltage. The three-phase reactor is a dummy load connected to the first three-phase inverter circuit and supplied with the three-phase AC voltage. The second three-phase inverter circuit rectifies a three-phase AC current flowing through the three-phase reactor and converts it into a second DC voltage. The step-down chopper circuit is connected to the second three-phase inverter circuit, has a pair of a first output terminal and a second output terminal, and steps down the second DC voltage to generate a third DC voltage having the same voltage value as the first DC voltage, and outputs the third DC voltage from a pair of a first output terminal and a second output terminal. The first feedback path connects the first output terminal and the first input terminal. The second feedback path connects the second output terminal and the second input terminal. The control circuit controls the operation of the boost chopper circuit, the first three-phase inverter circuit, the second three-phase inverter circuit, and the step-down chopper circuit. The test measuring instrument measures a measurement value for an operation test of the boost chopper circuit or the first three-phase inverter circuit.

[0009] The test apparatus further includes a first control measuring instrument and a second control measuring instrument. The first control measuring instrument measures a first feedback current value flowing through the first feedback path. The second control measuring instrument measures a second feedback current value flowing through the second feedback path.

[0010] The control circuit controls the operation of the step-down chopper circuit so as to reduce the difference between the first feedback current value and the second feedback current value.

[0011] In this configuration, the operation of the boost chopper circuit or the first three-phase inverter circuit can be measured by using the three-phase reactor as a dummy load. At this time, the difference in current flowing through the first feedback path and the second feedback path, i.e., the high-potential side feedback path and the low-potential side feedback path, is controlled to be small, so that undesired circulating current flowing through the first feedback path and the second feedback path is suppressed. Therefore, testing under desired conditions can be realized with higher accuracy. Effect of the Invention

[0012] According to the present invention, the power conversion device can be test-operated under desired conditions. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is an equivalent circuit diagram of the test device according to the first embodiment. [Diagram 2] FIG. 2 is an equivalent circuit diagram of a boost chopper circuit of the test device according to the first embodiment. [Diagram 3] FIG. 3 is an equivalent circuit diagram of the first inverter circuit of the test device according to the first embodiment. [Figure 4] FIG. 4 is an equivalent circuit diagram of the second inverter circuit of the test device according to the first embodiment. [Diagram 5] FIG. 5 is an equivalent circuit diagram of a step-down chopper circuit of the test apparatus according to the first embodiment. [Figure 6] FIG. 6 is a diagram showing a drive control concept of the first inverter circuit and an example of each drive control signal. [Figure 7] FIG. 7(A) is a graph showing the feedback current values ​​when the configuration and control of the first embodiment is used, and FIG. 7(B) is a graph showing the circulating current values ​​when the configuration and control of the first embodiment is used. [Figure 8] FIG. 8 is an equivalent circuit diagram of the test device according to the second embodiment. [Figure 9]FIG. 9(A) is a graph showing the feedback current values ​​when the configuration and control of the second embodiment is used, and FIG. 9(B) is a graph showing the circulating current values ​​when the configuration and control of the second embodiment is used. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] [First embodiment] A test device according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an equivalent circuit diagram of the test device according to the first embodiment. FIG. 2 is an equivalent circuit diagram of a step-up chopper circuit of the test device according to the first embodiment. FIG. 3 is an equivalent circuit diagram of a first inverter circuit of the test device according to the first embodiment. FIG. 4 is an equivalent circuit diagram of a second inverter circuit of the test device according to the first embodiment. FIG. 5 is an equivalent circuit diagram of a step-down chopper circuit of the test device according to the first embodiment. FIG. 6 is a diagram showing an example of a drive control concept of the first inverter circuit and each drive control signal.

[0015] As shown in Fig. 1, the test device 10 includes an AC input section 20, a full-wave rectifier circuit 30, an inductor L31, an inductor L32, an inductor L33, an inductor L34, a capacitor C31, a boost chopper circuit 40, an inverter circuit 50, a three-phase reactor 60, an inverter circuit 70, a step-down chopper circuit 80, a feedback path 91, a feedback path 92, and a control circuit 100. The inverter circuit 50 corresponds to the "first three-phase inverter circuit" of the present invention, and the inverter circuit 70 corresponds to the "second three-phase inverter circuit" of the present invention. The feedback path 91 corresponds to the "first feedback path" of the present invention, and the feedback path 92 corresponds to the "second feedback path" of the present invention.

[0016] The test device 10 also includes a voltage measuring instrument MA V2 , current measuring instrument MA A11 , current measuring instrument MA A12 , current measuring instrument MA A13 , current measuring instrument MA A2 , and current measuring instrument MA A3 Equipped with.

[0017] As a schematic circuit configuration, the AC input unit 20 is connected to a full-wave rectifier circuit 30. The full-wave rectifier circuit 30 is connected to a capacitor C31. The capacitor C31 is connected to an input terminal of a boost chopper circuit 40.

[0018] An output terminal of the boost chopper circuit 40 is connected to an input terminal (DC side terminal) of the inverter circuit 50. An output terminal (AC side terminal) of the inverter circuit 50 is connected to one end of a three-phase reactor 60.

[0019] The other end of the three-phase reactor 60 is connected to an input terminal (AC side terminal) of the inverter circuit 70. An output terminal (DC side terminal) of the inverter circuit 70 is connected to an input terminal of a step-down chopper circuit 80. A high potential side output terminal of the step-down chopper circuit 80 is connected to both ends of a capacitor C31 through a feedback path 91 and a feedback path 92.

[0020] By providing such feedback path 91 and feedback path 92, the test current can be fed back and regenerated for use in testing. In this case, unless the characteristic configuration and control of the present invention described below are implemented, the balance between the feedback current flowing through feedback path 91 and the feedback current flowing through feedback path 92 will be lost, causing a circulating current to occur. If a circulating current occurs, it will be impossible to perform testing under the desired conditions.

[0021] However, as shown in the following specific example, by using the configuration and control of the test apparatus of the present invention, it is possible to suppress the occurrence of circulating current and realize testing under desired conditions.

[0022] More specifically, each part of the test apparatus 10 has the following configuration.

[0023] (AC input section 20) The AC input unit 20 includes a commercial AC power supply and a line filter. The three-phase AC voltage from the AC input unit 20 is input to a full-wave rectifier circuit 30.

[0024] (Full wave rectifier circuit 30) The full-wave rectifier circuit 30 has a known circuit configuration using a plurality of diodes (rectifier elements). The full-wave rectifier circuit 30 converts an input three-phase AC voltage into a DC voltage and outputs the DC voltage.

[0025] The capacitor C31 is a so-called input capacitor for the boost chopper circuit 40. The capacitor C31 is connected in parallel to the output terminal of the full-wave rectifier circuit 30. More specifically, a high potential side terminal of the capacitor C31 is connected to the high potential side output terminal of the full-wave rectifier circuit 30, and a low potential side terminal of the capacitor C31 is connected to the low potential side output terminal of the full-wave rectifier circuit 30.

[0026] The inductor L31 is connected between the high potential side output terminal of the full wave rectifier circuit 30 and the high potential side terminal of the capacitor C31. The inductor L32 is connected between the low potential side output terminal of the full wave rectifier circuit 30 and the low potential side terminal of the capacitor C31.

[0027] The inductor L31, the inductor L32, and the capacitor C31 form a low-pass filter.

[0028] The inductor L33 is connected between the high potential side terminal of the capacitor C31 and the high potential side input terminal of the boost chopper circuit 40.

[0029] The inductor L34 is connected between the low potential side terminal of the capacitor C31 and the low potential side input terminal of the boost chopper circuit 40. The inductor L33 and the inductor L34 realize, for example, a function such as a noise filter.

[0030] A feedback path 91 is connected to the high potential terminal of the capacitor C31. A feedback path 92 is connected to the low potential terminal of the capacitor C31.

[0031] (Boost chopper circuit 40) As shown in FIG. 2, the boost chopper circuit 40 includes an inductor L40, a switching element Q41, a diode D42, and a capacitor C40.

[0032] One end of the inductor L40 is connected to the high potential side input terminal of the boost chopper circuit 40 (inductor L33).

[0033] The switching element Q41 is, for example, an FET. The source of the switching element Q41 is connected to the low potential side input terminal (inductor L34) of the boost chopper circuit 40. The drain of the switching element Q41 is connected to the other end of the inductor L40. The gate of the switching element Q41 is connected to the control circuit 100.

[0034] The anode of the diode D42 is connected to the node between the inductor L40 and the switching element Q41. The cathode of the diode D42 is connected to the high potential output terminal of the boost chopper circuit 40.

[0035] The capacitor C40 is connected between the cathode of the diode D42 and the source of the switching element Q41. In other words, the capacitor C40 is connected between the high potential side output terminal and the low potential side output terminal of the boost chopper circuit 40.

[0036] (Inverter circuit 50) 3, the inverter circuit 50 includes a plurality of switching elements Q1-Q6 (switching element Q1, switching element Q2, switching element Q3, switching element Q4, switching element Q5, and switching element Q6). The plurality of switching elements Q1-Q6 are the same FET.

[0037] The drain of the switching element Q1 is connected to the high potential side DC input terminal of the inverter circuit 50 (the high potential side output terminal of the boost chopper circuit 40). The source of the switching element Q1 is connected to the drain of the switching element Q2. The source of the switching element Q2 is connected to the low potential side DC input terminal of the inverter circuit 50 (the low potential side output terminal of the boost chopper circuit 40).

[0038] The gate of the switching element Q1 and the gate of the switching element Q2 are connected to the control circuit 100. The node of the source of the switching element Q1 and the drain of the switching element Q2 is connected to a first AC output terminal of the inverter circuit 50.

[0039] The drain of the switching element Q3 is connected to the high potential side DC input terminal of the inverter circuit 50 (the high potential side output terminal of the boost chopper circuit 40). The source of the switching element Q3 is connected to the drain of the switching element Q4. The source of the switching element Q4 is connected to the low potential side DC input terminal of the inverter circuit 50 (the low potential side output terminal of the boost chopper circuit 40).

[0040] The gate of the switching element Q3 and the gate of the switching element Q4 are connected to the control circuit 100. The node of the source of the switching element Q3 and the drain of the switching element Q4 is connected to the second AC output terminal of the inverter circuit 50.

[0041] The drain of the switching element Q5 is connected to the high potential side DC input terminal of the inverter circuit 50 (the high potential side output terminal of the boost chopper circuit 40). The source of the switching element Q5 is connected to the drain of the switching element Q6. The source of the switching element Q6 is connected to the low potential side DC input terminal of the inverter circuit 50 (the low potential side output terminal of the boost chopper circuit 40).

[0042] The gate of the switching element Q5 and the gate of the switching element Q6 are connected to the control circuit 100. The node of the source of the switching element Q5 and the drain of the switching element Q6 is connected to the third AC output terminal of the inverter circuit 50.

[0043] (3-phase reactor) As shown in FIG. 1, the three-phase reactor 60 includes a coil L61, a coil L62, and a coil L63.

[0044] The coil L61 is connected to a first AC output terminal of the inverter circuit 50. The coil L62 is connected to a second AC output terminal of the inverter circuit 50. The coil L63 is connected to a third AC output terminal of the inverter circuit 50.

[0045] (Inverter circuit 70) 4, the inverter circuit 70 includes a plurality of switching elements Q7-Q12 (switching element Q7, switching element Q8, switching element Q9, switching element Q10, switching element Q11, and switching element Q12). The plurality of switching elements Q7-Q12 are the same FET.

[0046] The source of switching element Q7 is connected to the drain of switching element Q8. The node of the source of switching element Q7 and the drain of switching element Q8 is connected to a third AC input terminal of inverter circuit 70. The third AC input terminal is connected to coil L63 of three-phase reactor 60.

[0047] The drain of the switching element Q7 is connected to the high potential side DC output terminal of the inverter circuit 70. The source of the switching element Q8 is connected to the low potential side DC output terminal of the inverter circuit 70.

[0048] The gate of the switching element Q7 and the gate of the switching element Q8 are connected to the control circuit 100.

[0049] The source of switching element Q9 is connected to the drain of switching element Q10. The node of the source of switching element Q9 and the drain of switching element Q10 is connected to a second AC input terminal of inverter circuit 70. The second AC input terminal is connected to coil L62 of three-phase reactor 60.

[0050] The drain of the switching element Q9 is connected to the high potential side DC output terminal of the inverter circuit 70. The source of the switching element Q10 is connected to the low potential side DC output terminal of the inverter circuit 70.

[0051] The gate of the switching element Q9 and the gate of the switching element Q10 are connected to the control circuit 100.

[0052] The source of switching element Q11 is connected to the drain of switching element Q12. A node of the source of switching element Q11 and the drain of switching element Q12 is connected to a first AC input terminal of inverter circuit 70. The first AC input terminal is connected to coil L61 of three-phase reactor 60.

[0053] The drain of the switching element Q11 is connected to the high potential side DC output terminal of the inverter circuit 70. The source of the switching element Q12 is connected to the low potential side DC output terminal of the inverter circuit 70.

[0054] The gate of the switching element Q11 and the gate of the switching element Q12 are connected to the control circuit 100.

[0055] (Step-down chopper circuit 80) As shown in FIG. 5, the step-down chopper circuit 80 includes an inductor L80, a diode D81, a switching element Q82, and capacitors C81 and C82.

[0056] The capacitor C81 is connected between the high potential side input terminal and the low potential side input terminal of the step-down chopper circuit 80. The high potential side input terminal of the step-down chopper circuit 80 is connected to the high potential side DC output terminal of the inverter circuit 70, and the low potential side input terminal of the step-down chopper circuit 80 is connected to the low potential side DC output terminal of the inverter circuit 70.

[0057] The drain of switching element Q82 connects to the high potential input terminal of step-down chopper circuit 80. The source of switching element Q82 connects to the cathode of diode D81. The anode of diode D81 connects to the low potential input terminal of step-down chopper circuit 80.

[0058] One end of inductor L80 is connected to the node between the source of switching element Q82 and the cathode of diode D81. The other end of inductor L80 is connected to the high potential output terminal of step-down chopper circuit 80.

[0059] The capacitor C82 is connected between the high potential side output terminal and the low potential side output terminal of the step-down chopper circuit 80. The low potential side output terminal of the step-down chopper circuit 80 is connected to the low potential side input terminal of the step-down chopper circuit 80.

[0060] (Return Route 91, Return Route 92) 1, a feedback path 91 connects the high potential side output terminal of the step-down chopper circuit 80 and the high potential side terminal of the capacitor C31. A feedback path 92 connects the low potential side output terminal of the step-down chopper circuit 80 and the low potential side terminal of the capacitor C31.

[0061] (Each measuring instrument) The test device 10 includes a voltage measuring instrument MA V2 , current measuring instrument MA A11 , current measuring instrument MA A12 , current measuring instrument MA A13 , current measuring instrument MA A2 , and current measuring instrument MA A3 Equipped with.

[0062] Voltage measuring instrument MA V2 is connected across the capacitor C40 of the boost chopper circuit 40. V2 measures the output voltage of the boost chopper circuit 40 and outputs it to the control circuit 100.

[0063] Current Measuring Instrument MA A11 , current measuring instrument MA A12 , current measuring instrument MA A13 , current measuring instrument MA A2 , and current measuring instrument MA A3 is, for example, a current sensor that utilizes mutual induction.

[0064] Current Measuring Instrument MA A11is connected in series to coil L61. Current measuring device MA A11 senses the current flowing through the coil L61 of the three-phase reactor 60 and outputs the result to the control circuit 100.

[0065] Current Measuring Instrument MA A12 is connected in series to coil L62. Current measuring device MA A12 The sense amplifier 110 senses the current flowing through the coil L62 of the three-phase reactor 60 and outputs the sensed current to the control circuit 100.

[0066] Current Measuring Instrument MA A13 is connected in series to coil L63. Current measuring device MA A13 senses the current flowing through the coil L63 of the three-phase reactor 60 and outputs the result to the control circuit 100.

[0067] Current Measuring Instrument MA A2 is connected in series (inserted) in the feedback path 91. A2 The feedback circuit 91 senses the current (first feedback current) flowing through the feedback path 91 and outputs the sensed current to the control circuit 100.

[0068] Current Measuring Instrument MA A3 is connected in series (inserted) in the feedback path 92. A3 The feedback circuit 92 senses the current (second feedback current) flowing through the feedback path 92 and outputs the sensed current to the control circuit 100.

[0069] Current Measuring Instrument MA A2 and current measuring instrument MA A3 correspond to the "first control measuring instrument" and the "second control measuring instrument", respectively. A11 , current measuring instrument MA A12 , current measuring instrument MA A13 corresponds to the "test measuring instrument." Note that the test apparatus 10 may include a current measuring instrument (not shown) connected in series to the diode D42 as the test measuring instrument. This current measuring instrument is connected, for example, between the node where the capacitor C40 is connected to the high potential side output terminal and the cathode of the diode D42.

[0070] (Control circuit 100) Control circuit 100 is, for example, an IC having a calculation capability such as a DSP. Control circuit 100 is connected to switching element Q41 of boost chopper circuit 40, multiple switching elements Q1-Q6 of inverter circuit 50, multiple switching elements Q7-Q12 of inverter circuit 70, and switching element Q82 of step-down chopper circuit 80.

[0071] The control circuit 100 provides switching control signals to each of the switching elements Q41, Q1-Q6, Q7-Q12, and Q82. Each of the switching elements Q41, Q1-Q6, Q7-Q12, and Q82 is turned on and off by the switching control signals. This controls the operation of the step-up chopper circuit 40, the inverter circuit 50, the inverter circuit 70, and the step-down chopper circuit 80. The details of these operation controls will be described later.

[0072] (Operation of Test Apparatus 10) When power is supplied from the AC input unit 20, the full-wave rectifier circuit 30 rectifies the AC voltage and outputs a DC voltage of a predetermined voltage value.

[0073] A circuit including the capacitor C31 and the multiple inductors L31, L32, L33, and L34 suppresses various types of noise superimposed on the DC voltage. The DC voltage from which the various types of noise have been suppressed is input to a boost chopper circuit 40.

[0074] The boost chopper circuit 40 boosts the input DC voltage (first DC voltage) and outputs the boosted DC voltage (second DC voltage) to the inverter circuit 50. At this time, the operation of the boost chopper circuit 40 is controlled by a switching control signal for boost control from the control circuit 100.

[0075] More specifically, the control circuit 100 includes a voltage measuring instrument MA V2Using this measured voltage, a switching control signal is generated for switching element Q41 of boost chopper circuit 40 so that boost chopper circuit 40 obtains the desired DC output voltage from the DC input voltage. Control circuit 100 provides this boost control switching control signal to switching element Q41. Switching element Q41 is turned on and off by the boost control switching control signal, so that boost chopper circuit 40 outputs the desired DC output voltage to inverter circuit 50.

[0076] The inverter circuit 50 converts a DC voltage into a three-phase AC current by open loop control and outputs it to the three-phase reactor 60. That is, the control circuit 100 generates a first inverter control signal to the multiple switching elements Q1-Q6 of the inverter circuit 50 so as to generate a three-phase AC current of a predetermined voltage at a predetermined frequency as shown in Fig. 6 without referring to the voltages and currents related to the control of the inverter circuit 50.

[0077] A three-phase AC current flows through the three-phase reactor 60 from the inverter circuit 50. The operation of the three-phase reactor 60 is controlled so as to simulate the operation of a dummy load (for example, a field winding of a brushless motor). This control is realized by controlling the operation of the inverter circuit 70.

[0078] The inverter circuit 70 converts the three-phase AC current from the three-phase reactor 60 into a DC voltage, and outputs it to the step-down chopper circuit 80 .

[0079] At this time, the control circuit 100 performs vector control of the three-phase AC current so as to realize a predetermined operation of the dummy load (for example, a frequency and torque command value corresponding to a speed command value of a brushless motor). That is, the control circuit 100 generates switching control signals for the multiple switching elements Q7-Q12 of the inverter circuit 70 so that a current that realizes the predetermined operation of the dummy load flows through each phase (coils L61, L62, L63) of the three-phase reactor 60. The multiple switching elements Q7-Q12 are turned on and off by the switching control signals for realizing this dummy operation. As a result, the three-phase reactor 60 operates as if it were a dummy load used for testing, and a three-phase AC current corresponding to this operation flows through the three-phase reactor 60.

[0080] The step-down chopper circuit 80 steps down the output voltage of the inverter circuit 70 to generate a desired output voltage (third DC voltage). This output voltage is set to the same voltage value as the voltage across the capacitor C31 (first DC voltage). The output voltage (output power) from the step-down chopper circuit 80 is regenerated (fed back) to both ends of the capacitor C31, in other words, the input side of the step-up chopper circuit 40, through a feedback path 91 and a feedback path 92.

[0081] With such a configuration and operation, the test device 10 can perform an operation test of the inverter circuit 50 and the boost chopper circuit 40 when supplying power to a load to be simulated (for example, a motor of an EV vehicle, etc.). Then, by acquiring the measurement values ​​(measurement values ​​for operation test) of the test measuring instrument by the control circuit 100, the test device 10 or an evaluator can evaluate the performance, reliability, etc. of the inverter circuit 50 and the boost chopper circuit 40 by analyzing the measurement values.

[0082] Furthermore, in this configuration, the output power of the step-down chopper circuit 80 is regenerated to the input side of the step-up chopper circuit 40 (a feedback current is obtained), so that the power consumption of the test apparatus 10 can be reduced.

[0083] Here, if step-down chopper circuit 80 is subjected to general constant voltage control, the on time and off time will not be equal. Furthermore, the current path differs between when switching element Q82 in step-down chopper circuit 80 is on (conducting) and when it is off (open). This causes an imbalance between the feedback current (first feedback current) flowing through feedback path 91 and the feedback current (second feedback current) flowing through feedback path 92, causing a circulating current to flow through feedback path 91 and feedback path 92. The flow of the circulating current makes it impossible to perform high-precision measurement.

[0084] Therefore, the test apparatus 10 performs control so that the difference between the current value of the first feedback current (first feedback current value) and the current value of the second feedback current (second feedback current value) becomes small, in other words, so that the first feedback current value and the second feedback current value become the same.

[0085] More specifically, the current measuring instrument MA A2 senses the first feedback current value Ip and outputs it to the control circuit 100. At this time, for example, the first feedback current value Ip is measured so that it is a positive value when it flows from the output terminal of the step-down chopper circuit 80 toward the capacitor C31, and is a negative value when it flows in the reverse direction.

[0086] Current Measuring Instrument MA A3 senses the second feedback current value In and outputs it to the control circuit 100. The second feedback current value In is measured so that it is a negative value when it flows from the output terminal of the step-down chopper circuit 80 toward the capacitor C31, and is a positive value when it flows in the reverse direction.

[0087] The control circuit 100 acquires the first feedback current value Ip and the second feedback current value In. The control circuit 100 calculates the difference between the first feedback current value Ip and the second feedback current value In.

[0088] Control circuit 100 generates a switching control signal for step-down chopper circuit 80 so that this difference (Ip-In) approaches 0. That is, control circuit 100 performs constant current control on step-down chopper circuit 80. Then, switching element Q82 of step-down chopper circuit 80 operates in response to this switching control signal.

[0089] As a result, the difference between the first feedback current value Ip and the second feedback current value In becomes smaller (approaching zero), and the circulating current is suppressed.

[0090] In this way, by suppressing the circulating current, the test apparatus 10 can realize the test state with high accuracy. That is, the test apparatus 10 can perform a test operation of the power conversion device that supplies power to the dummy load under desired conditions. Therefore, the test apparatus 10 can realize the test under the desired conditions with high accuracy.

[0091] Fig. 7(A) is a graph showing each feedback current value when the configuration and control of the first embodiment are used. Fig. 7(B) is a graph showing a circulating current value when the configuration and control of the first embodiment are used.

[0092] As shown in Fig. 7(A), by using the configuration and control of the first embodiment, the first feedback current value Ip and the second feedback current value In are steadily almost the same, and as a result, the circulating current is steadily almost zero, as shown in Fig. 7(B).

[0093] Therefore, the test apparatus 10 can realize the desired test conditions with high precision, and can perform operation tests of the inverter circuit 50 and the boost chopper circuit 40 with high precision.

[0094] [Second embodiment] A test apparatus according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 8 is an equivalent circuit diagram of a test apparatus according to a second embodiment.

[0095] The test apparatus 10A according to the second embodiment differs from the test apparatus 10 according to the first embodiment in the control of the step-down chopper circuit 80. That is, the control of the control circuit 100A is different from that of the control circuit 100. As shown in FIG. 9, the test apparatus 10A has a current measuring instrument MA A2 , and current measuring instrument MA A3 Voltage measuring instrument MA V3 It differs in that it has

[0096] The control circuit 100A performs vector control of the first phase current Ia, the second phase current Ib, and the third phase current Ic so that the total current value Isum of the first phase current Ia flowing through coil L61 of the three-phase reactor 60, the second phase current Ib flowing through coil L62, and the third phase current Ic flowing through coil L63 becomes zero.

[0097] More specifically, the current measuring instrument MA A11 The first phase current Ia is sensed and output to the control circuit 100A. The first phase current Ia is measured as a positive value when it flows from the boost chopper circuit 40 to the coil L61, and as a negative value when it flows in the reverse direction.

[0098] Current Measuring Instrument MA A12 The second phase current Ib is sensed and output to the control circuit 100A. The second phase current Ib is measured as a positive value when it flows from the boost chopper circuit 40 toward the coil L62, and as a negative value when it flows in the reverse direction.

[0099] Current Measuring Instrument MA A13 The third phase current Ic is sensed and output to the control circuit 100A. The third phase current Ic is measured as a positive value when it flows from the boost chopper circuit 40 toward the coil L63, and as a negative value when it flows in the reverse direction.

[0100] In this way, in the test device 10A, the current measuring instrument MA A11 , current measuring instrument MA A12 , current measuring instrument MA A13 is used as the third control measuring instrument.

[0101] The control circuit 100A acquires the first phase current Ia, the second phase current Ib, and the third phase current Ic, and calculates a total current value Isum by adding up the first phase current Ia, the second phase current Ib, and the third phase current Ic.

[0102] The control circuit 100A generates a switching control signal to the inverter circuit 70 so that the total current value Isum approaches zero.

[0103] This maintains a balance between the first phase current Ia, the second phase current Ib, and the third phase current Ic (the total current value Isum approaches 0). V3 Even if constant voltage control is performed by the step-down chopper circuit 80 using the measured output voltage, the difference between the first feedback current value Ip and the second feedback current value In becomes small, and the circulating current is suppressed.

[0104] In this way, by suppressing the circulating current, the test apparatus 10A can realize the test state with high accuracy. That is, the test apparatus 10A can perform a test operation of the power conversion device that supplies power to the dummy load under desired conditions. Therefore, the test apparatus 10A can realize the test under the desired conditions with high accuracy.

[0105] Fig. 9(A) is a graph showing each feedback current value when the configuration and control of the second embodiment are used, and Fig. 9(B) is a graph showing a circulating current value when the configuration and control of the second embodiment are used.

[0106] As shown in Fig. 9(A), by using the configuration and control of the second embodiment, the first feedback current value Ip and the second feedback current value In are steadily almost the same. As a result, the circulating current is steadily almost zero, as shown in Fig. 9(B).

[0107] Therefore, the test apparatus 10A can realize the desired test conditions with high precision, and can perform the operation tests of the inverter circuit 50 and the boost chopper circuit 40 with high precision.

[0108] The diodes of the step-up chopper circuit 40 and the step-down chopper circuit 80 according to the above-described embodiments can be replaced with switching elements (e.g., FETs). That is, the step-up chopper circuit 40 and the step-down chopper circuit 80 can be replaced from an asynchronous type to a synchronous type. [Explanation of symbols]

[0109] 10, 10A: Test equipment 20: AC input section 30: Full wave rectifier circuit 40: Boost chopper circuit 50: Inverter circuit 60: 3-phase reactor 70: Inverter circuit 80: Step-down chopper circuit 91, 92: Return route 100, 100A: Control circuit C31, C40, C81, C82: Capacitors D42, D81: Diode Ia: 1st phase current Ib: 2nd phase current Ic: 3rd phase current Ip: First feedback current value In: Second feedback current value L31, L32, L33, L34: Inductors L40: Inductor L61, L62, L63: Coil L80: Inductor MAA11, MAA12, MAA13, MAA2, MAA3: Current measuring instruments MAV2: Voltage Meter Q1-Q12: switching elements Q41: Switching elements Q82: Switching elements

Claims

1. a boost chopper circuit having a pair of a first input terminal and a second input terminal, and outputting a first DC voltage; a first three-phase inverter circuit that generates a three-phase AC voltage from the first DC voltage; a three-phase reactor that is a dummy load connected to the first three-phase inverter circuit and to which the three-phase AC voltage is supplied; a second three-phase inverter circuit that rectifies the three-phase AC current flowing through the three-phase reactor and converts it into a second DC voltage; a step-down chopper circuit connected to the second three-phase inverter circuit, comprising a pair of first and second output terminals, stepping down the second DC voltage by constant current control and outputting the voltage from the pair of the first and second output terminals; a first feedback path connecting the first output terminal and the first input terminal; a second feedback path connecting the second output terminal and the second input terminal; a control circuit that controls operations of the step-up chopper circuit, the first three-phase inverter circuit, the second three-phase inverter circuit, and the step-down chopper circuit; a test measuring instrument for measuring a measurement value for an operation test of the step-up chopper circuit or the first three-phase inverter circuit; Equipped with a first control measuring instrument that measures a first feedback current value flowing through the first feedback path; a second control measuring instrument that measures a second feedback current value flowing through the second feedback path; Further equipped with the control circuit controls an operation of the step-down chopper circuit so as to reduce a difference between the first feedback current value and the second feedback current value. Test equipment.

2. a boost chopper circuit having a pair of a first input terminal and a second input terminal and outputting a first DC voltage; a first three-phase inverter circuit that generates a three-phase AC voltage from the first DC voltage; a three-phase reactor that is a dummy load connected to the first three-phase inverter circuit and to which the three-phase AC voltage is supplied; a second three-phase inverter circuit that rectifies the three-phase AC current flowing through the three-phase reactor and converts it into a second DC voltage; a step-down chopper circuit connected to the second three-phase inverter circuit, comprising a pair of a first output terminal and a second output terminal, for stepping down the second DC voltage to generate a third DC voltage and outputting the third DC voltage from the pair of the first output terminal and the second output terminal; a first feedback path connecting the first output terminal and the first input terminal; a second feedback path connecting the second output terminal and the second input terminal; a control circuit that controls operations of the step-up chopper circuit, the first three-phase inverter circuit, the second three-phase inverter circuit, and the step-down chopper circuit; a test measuring instrument for measuring a measurement value for an operation test of the step-up chopper circuit or the first three-phase inverter circuit; Equipped with a plurality of third control measuring instruments each measuring the three-phase AC current individually; The control circuit includes: a step-down chopper circuit is subjected to constant voltage control, and an operation of the second three-phase inverter circuit is controlled so that a total current value obtained by adding up the three-phase AC currents approaches zero; Test equipment.

3. The control circuit includes: vector control of the three-phase AC current is performed so that a current that realizes a frequency and a torque command value corresponding to a speed command value of the brushless motor flows through each phase of the three-phase reactor, so that the three-phase reactor is simulated as a field winding of a brushless motor; 3. A test device according to claim 1 or 2.

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