Test Equipment

Abstract

To perform tests of a step-up chopper and an inverter simultaneously while they are connected.SOLUTION: A three-phase inverter circuit 50 generates a three-phase AC voltage from a first DC voltage output from a step-up chopper circuit 40. A three-phase reactor 60 is connected with the three-phase inverter circuit 50, functioning as a pseudo load supplied with the three-phase AC voltage. A three-phase inverter circuit 70 rectifies a three-phase AC current flowing in the three-phase reactor 60. A step-down chopper circuit 80 is connected with the three-phase inverter circuit 70, stepping down a DC voltage and outputs the stepped-down DC voltage. Feedback paths 91 and 92 connect output terminals of the step-down chopper circuit 80 with an input terminal side of the step-up chopper circuit 40. An energy supplied from a DC voltage source to the pseudo load through the step-up chopper circuit 40 is regenerated to the step-up chopper circuit 40 via the feedback paths 91 and 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] Patent Document 1 describes an inverter testing device. The device in Patent Document 1 steps down the input voltage using a step-down chopper and applies it to the inverter under test. The device in Patent Document 1 drives the inverter under test and generates three-phase AC currents, U-phase, V-phase, and W-phase, from the applied DC voltage.

[0003] The device of Patent Document 1 passes this three-phase AC current through a reactor (filter), and then returns it to DC through a transformer and filter in a dummy load inverter.The device of Patent Document 1 then regenerates the DC current at the input stage of a step-down chopper.

[0004] The transformer at the rear of the inverter under test boosts the drive voltage of the inverter under test 1 to prevent it from flowing through a reactor (filter) and causing a voltage drop that would prevent energy regeneration. The step-down chopper at the front of the inverter under test controls the drive voltage of the inverter under test to a constant value when regeneration is performed in this way. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-189630 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, many automotive powertrains, such as HEVs, PHEVs, and BEVs, have increased the inverter drive voltage to approximately 600 to 800 V in order to achieve higher efficiency, and are equipped with a boost chopper circuit in front of the inverter.

[0007] However, while the device in Patent Document 1 can test the inverter, it cannot simultaneously test the boost chopper circuit required in the upstream stage of the inverter. Furthermore, even if the boost chopper circuit is tested separately, accurate testing cannot be performed because the ripple current and other parameters differ depending on whether the inverter is connected in the downstream stage or not.

[0008] For this reason, there is a demand for a device that can test the boost chopper and inverter simultaneously while they are connected.

[0009] Furthermore, the device in Patent Document 1 uses a transformer, but some automotive inverters have an output power of over 200 kW, and the frequency is relatively low, ranging from the motor's stopped state (0 kHz) to its maximum rotation speed (200 Hz even at 12,000 rpm). This requires a huge transformer, which significantly increases the size of the test device.

[0010] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a test device that can simultaneously test a boost chopper and an inverter while they are connected, and that can be prevented from becoming large in size. [Means for solving the problem]

[0011] A testing apparatus according to one aspect of the present invention includes a DC voltage source, a boost chopper circuit, a first three-phase inverter circuit, a three-phase reactor, a second three-phase inverter circuit, a buck chopper circuit, a control circuit, a first feedback path, and a second feedback path. The boost chopper circuit is connected to the DC voltage source, has a pair of first and second input terminals, 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 connected to the first three-phase inverter circuit and functions as a dummy load to which the three-phase AC voltage is supplied. The second three-phase inverter circuit rectifies the three-phase AC current flowing through the three-phase reactor and converts it into a second DC voltage. The buck chopper circuit is connected to the second three-phase inverter circuit, has a pair of first and second output terminals, and steps down the second DC voltage and outputs it from the pair of first and second output terminals. The control circuit controls the operation of the step-up chopper circuit, the first three-phase inverter circuit, the second three-phase inverter circuit, and the step-down chopper circuit. 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 step-down chopper circuit to regenerate energy supplied from the DC voltage source to the dummy load via the first feedback path and the second feedback path.

[0012] In this configuration, the output voltage of the test equipment is adjusted to the input voltage of the boost chopper circuit by the step-down chopper circuit. The output voltage of this step-down chopper circuit is then regenerated to the input terminal of the boost chopper circuit. Therefore, the desired test voltage is supplied when the step-up chopper circuit and the first three-phase inverter circuit are connected. In addition, by using the step-down chopper circuit, the regenerative voltage can be generated without using a large device such as a transformer. [Effects of the Invention]

[0013] According to this invention, the boost chopper and the inverter can be tested simultaneously while they are connected, which prevents the device from becoming too large. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is an equivalent circuit diagram of a test device according to an embodiment of the present invention. [Figure 2] FIG. 2 is an equivalent circuit diagram of a boost chopper circuit of the test device according to the embodiment of the present invention. [Figure 3] FIG. 3 is an equivalent circuit diagram of a first inverter circuit of the test device according to the embodiment of the present invention. [Figure 4] FIG. 4 is an equivalent circuit diagram of a second inverter circuit of the test device according to the embodiment of the present invention. [Figure 5] FIG. 5 is an equivalent circuit diagram of a step-down chopper circuit of a test device according to an embodiment of the present invention. [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. DETAILED DESCRIPTION OF THE INVENTION

[0015] A test apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an equivalent circuit diagram of the test apparatus according to an embodiment of the present invention. FIG. 2 is an equivalent circuit diagram of a boost chopper circuit of the test apparatus according to an embodiment of the present invention. FIG. 3 is an equivalent circuit diagram of a first inverter circuit of the test apparatus according to an embodiment of the present invention. FIG. 4 is an equivalent circuit diagram of a second inverter circuit of the test apparatus according to an embodiment of the present invention. FIG. 5 is an equivalent circuit diagram of a step-down chopper circuit of the test apparatus according to an embodiment of the present invention. FIG. 6 is a diagram showing an example of a drive control concept for the first inverter circuit and each drive control signal.

[0016] 1, the test apparatus 10 includes an AC input unit 20, a full-wave rectifier circuit 30, inductors L31, L32, L33, and 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, feedback paths 91 and 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.

[0017] 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 For testing purposes, at least a voltage measuring instrument MA V2 , current measuring instrument MA A11 , current measuring instrument MA A12 , current measuring instrument MA A13 It would be good if this was provided.

[0018] 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 .

[0019] 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.

[0020] The other end of the three-phase reactor 60 is connected to an input terminal (AC side terminal) of an 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 via a feedback path 91 and a feedback path 92.

[0021] By providing such feedback path 91 and feedback path 92, the test current can be fed back and regenerated for use in the test.

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

[0023] (AC input unit 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 the 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, the 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 the 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] Inductor L31 is connected between the high potential side output terminal of full-wave rectifier circuit 30 and the high potential side terminal of capacitor C31. Inductor L32 is connected between the low potential side output terminal of full-wave rectifier circuit 30 and the low potential side terminal of 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 inductors L33 and L34 realize, for example, a function such as a noise filter.

[0030] A feedback path 91 is connected to the high potential side terminal of the capacitor C31. A feedback path 92 is connected to the low potential side 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] Switching element Q41 is, for example, an FET. The source of switching element Q41 is connected to the low potential side input terminal (inductor L34) of boost chopper circuit 40. The drain of switching element Q41 is connected to the other end of inductor L40. The gate of switching element Q41 is connected to control circuit 100.

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

[0035] Capacitor C40 is connected between the cathode of diode D42 and the source of switching element Q41. In other words, capacitor C40 is connected between the high potential side output terminal and the low potential side output terminal of 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 the first AC output terminal of the inverter circuit 50.

[0039] The drain of switching element Q3 is connected to the high potential side DC input terminal of inverter circuit 50 (high potential side output terminal of boost chopper circuit 40). The source of switching element Q3 is connected to the drain of switching element Q4. The source of switching element Q4 is connected to the low potential side DC input terminal of inverter circuit 50 (low potential side output terminal of 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 switching element Q5 is connected to the high potential side DC input terminal of inverter circuit 50 (high potential side output terminal of boost chopper circuit 40). The source of switching element Q5 is connected to the drain of switching element Q6. The source of switching element Q6 is connected to the low potential side DC input terminal of inverter circuit 50 (low potential side output terminal of 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, inverter circuit 70 includes multiple switching elements Q7-Q12 (switching element Q7, switching element Q8, switching element Q9, switching element Q10, switching element Q11, and switching element Q12). Multiple 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 between 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 between 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. The node between 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 switch Q82 connects to the high potential side input terminal of step-down chopper circuit 80. The source of switch Q82 connects to the cathode of diode D81. The anode of diode D81 connects to the low potential side 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, and 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] That is, the feedback path 91 connects the high potential side output terminal of the step-down chopper circuit 80 and the high potential side input terminal of the step-up chopper circuit 40. The feedback path 92 connects the low potential side output terminal of the step-down chopper circuit 80 and the low potential side input terminal of the step-up chopper circuit 40.

[0062] (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.

[0063] 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.

[0064] 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.

[0065] Current measuring instrument MA A11 is connected in series to the coil L61. A11 senses the current flowing through the coil L61 of the three-phase reactor 60 and outputs the sensed current to the control circuit 100.

[0066] Current measuring instrument MA A12 is connected in series with the coil L62. A12 senses the current flowing through the coil L62 of the three-phase reactor 60 and outputs the sensed current to the control circuit 100.

[0067] Current measuring instrument MA A13 is connected in series to coil L63. Current measuring instrument MAA13 senses the current flowing through the coil L63 of the three-phase reactor 60 and outputs the sensed current to the control circuit 100.

[0068] Current measuring instrument MA A2 is connected in series (inserted) in the feedback path 91. A2 senses the current (first feedback current) flowing through the feedback path 91 and outputs it to the control circuit 100.

[0069] Current measuring instrument MA A3 is connected in series (inserted) in the feedback path 92. A3 senses the current (second feedback current) flowing through the feedback path 92 and outputs it to the control circuit 100.

[0070] Current measuring instrument MA A11 , current measuring instrument MA A12 , current measuring instrument MA A13 , voltage measuring instrument MA V2 can be used as a test meter. The test apparatus 10 may also include a current meter (not shown) connected in series with the diode D42 as a test meter. This current meter is connected, for example, between the node where the capacitor C40 is connected to the high-potential output terminal and the cathode of the diode D42.

[0071] (Control circuit 100) Control circuit 100 is, for example, an IC having a processing capability such as a DSP, and is connected to switching element Q41 of step-up 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.

[0072] Control circuit 100 provides switching control signals to switching elements Q41, Q1-Q6, Q7-Q12, and Q82. Each of switching elements Q41, Q1-Q6, Q7-Q12, and Q82 is turned on and off by these switching control signals. This controls the operation of step-up chopper circuit 40, inverter circuit 50, inverter circuit 70, and step-down chopper circuit 80, respectively. Details of these operation controls will be described later.

[0073] (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.

[0074] A circuit consisting of capacitor C31 and multiple inductors L31, L32, L33, and L34 suppresses various types of noise superimposed on the DC voltage. The DC voltage from which various types of noise have been suppressed is input to a boost chopper circuit 40.

[0075] 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.

[0076] More specifically, the control circuit 100 includes a voltage measuring instrument MA V2 Using 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.

[0077] The inverter circuit 50 converts a DC voltage into a three-phase AC current by open-loop control and outputs the three-phase AC current to the three-phase reactor 60. That is, the control circuit 100 generates a first inverter control signal and supplies it 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 involved in the control of the inverter circuit 50.

[0078] 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.

[0079] 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 .

[0080] At this time, control circuit 100 performs vector control of three-phase AC current 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, control circuit 100 generates switching control signals for multiple switching elements Q7-Q12 of 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 three-phase reactor 60. Multiple switching elements Q7-Q12 are turned on and off by the switching control signals for realizing this dummy operation. As a result, 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 three-phase reactor 60.

[0081] The step-down chopper circuit 80 generates a desired output voltage (third DC voltage) by stepping down the output voltage of the inverter circuit 70 through current control, which will be described later. This output voltage is set to the same voltage value as the voltage across the capacitor C31 (first DC voltage).

[0082] The output voltage (output power) from the step-down chopper circuit 80 is regenerated (fed back) through a feedback path 91 and a feedback path 92 to both ends of the capacitor C31, in other words, to the input side of the step-up chopper circuit 40.

[0083] With this configuration and operation, the test device 10 can perform an operation test of a circuit in which a boost chopper circuit 40 and an inverter circuit 50 are connected when supplying power to a load to be simulated (e.g., a motor of an EV vehicle, etc.).

[0084] Then, by having the control circuit 100 acquire the measurement values ​​(measurement values ​​for operation test) of the test measuring instrument, the test device 10 or an evaluator can analyze these measurement values ​​to evaluate the performance, reliability, etc. of the circuit in which the boost chopper circuit 40 and the inverter circuit 50 are connected. For example, the test device 10 measures the current flowing through the three-phase reactor using a current measuring instrument MA A11 , current measuring instrument MA A12 , current measuring instrument MA A13 and the output voltage of the boost chopper circuit 40 is observed with a voltage measuring instrument MAV2, the performance, reliability, etc. of the circuit in which the boost chopper circuit 40 and the inverter circuit 50 are connected can be evaluated.

[0085] 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.

[0086] At this time, in the test device 10, energy is regenerated on the input side of the boost chopper circuit 40. Therefore, the test device 10 can regenerate energy appropriately for testing a circuit in which the boost chopper circuit 40 and the inverter circuit 50 are connected.

[0087] That is, conventionally, it has been common to feed back the output of an inverter circuit 70 that converts AC to DC to the input side of the inverter circuit 50. This is because the output voltage of the inverter circuit 70 is different (higher) than the input voltage of the boost chopper circuit 40.

[0088] In such a conventional configuration, as shown by the problem of the conventional technology, it has not been possible to accurately test the circuit in which the boost chopper circuit 40 and the inverter circuit 50 are connected.

[0089] However, by providing the step-down chopper circuit 80 in the test device 10, the output voltage of the inverter circuit 70 can be matched to the input voltage of the step-up chopper circuit 40. Therefore, energy can be regenerated on the input side of the step-up chopper circuit 40, and the circuit in which the step-up chopper circuit 40 and the inverter circuit 50 are connected can be tested with high accuracy while suppressing power consumption.

[0090] It is more preferable that the test device 10 performs the following control.

[0091] (First control) The test device 10 performs control so that the difference between the current value of the first feedback current flowing through the feedback path 91 (first feedback current value) and the current value of the second feedback current flowing through the feedback path 92 (second feedback current value) becomes small, and further so that the first feedback current value and the second feedback current value become the same.

[0092] More specifically, the current measuring instrument MA A2 senses the first feedback current value Ip and outputs it to the control circuit 100. A3 senses the second feedback current value In and outputs it to the control circuit 100.

[0093] The control circuit 100 acquires the first feedback current value Ip and the second feedback current value In. The control circuit 100 performs constant current control on the step-down chopper circuit 80 so that the difference (Ip-In) approaches zero, and generates a switching control signal for the step-down chopper circuit 80.

[0094] As a result, the difference between the first feedback current value Ip and the second feedback current value In becomes smaller (approaching 0), and the circulating current is suppressed.

[0095] In this way, the circulating current is suppressed, allowing the test apparatus 10 to realize a test state with even higher accuracy, and therefore the test apparatus 10 can realize a test under desired conditions with high accuracy.

[0096] (Second control) The control circuit 100 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 the coil L61 of the three-phase reactor 60, the second phase current Ib flowing through the coil L62, and the third phase current Ic flowing through the coil L63 becomes zero.

[0097] More specifically, the current measuring instrument MA A11 The current measuring device MA senses the first phase current Ia and outputs it to the control circuit 100. A12 senses the second phase current Ib and outputs it to the control circuit 100. A13 senses the third phase current Ic and outputs it to the control circuit 100.

[0098] The control circuit 100 acquires the first phase current Ia, the second phase current Ib, and the third phase current Ic. The control circuit 100 sums the first phase current Ia, the second phase current Ib, and the third phase current Ic to calculate a total current value Isum. The control circuit 100 generates a switching control signal for the inverter circuit 70 so that the total current value Isum approaches zero.

[0099] 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.

[0100] In this way, the circulating current is suppressed, allowing the test apparatus 10 to realize a test state with even higher accuracy, and therefore the test apparatus 10 can realize a test under desired conditions with high accuracy.

[0101] 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 (for example, 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]

[0102] 10: 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: Control circuit C31, C40, C81, C82: Capacitors D42, D81: Diodes 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: Coils L80: Inductor MAA11, MAA12, MAA13, MAA2, MAA3: Current measuring instruments MAV2: Voltage Meter Q1-Q12: Switching elements Q41: Switching element Q82: Switching element

Claims

1. A DC voltage source; a boost chopper circuit connected to the DC voltage source, 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 as a dummy load connected to the first three-phase inverter circuit and supplied with the three-phase AC voltage; 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 and outputting the stepped-down voltage from the pair of the first output terminal and the second output terminal; a control circuit for controlling 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 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; Equipped with the control circuit controls the step-down chopper circuit to regenerate energy supplied from the DC voltage source to the dummy load through the first feedback path and the second feedback path; Test equipment.

2. the boost chopper circuit and the first three-phase inverter circuit are a power converter under test; 2. The test device of claim 1.

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