JP4032731B2 - Inverter test equipment - Google Patents

Description

【００２７】
による電圧方程式を満足するように制御が行われる。（２）式において、
Ｖ_d , Ｖ_q ：ｄ，ｑ軸の電機子電圧、ｉ_d , ｉ_q ：ｄ，ｑ軸の電機子電流、Ｒ：電機子抵抗、Ｌ_d , Ｌ_q ：ｄ，ｑ軸インダクタンス、ω_m ：角速度（Ｎに対応）、ｐ：ｄ／ｄｔ、φ_a ：永久磁石による電機子鎖交磁束の最大値×（３／２の平方根）、ｐ_n ：極対数である。Ｔは出力トルクで
Ｔ＝〔ｐ_n ｛φ_a ｉ_q ＋（Ｌ_d −Ｌ_q ）ｉ_d ｉ_q ｝------（３）
である。
【００２８】
図３は上記（２）式による電圧変換方程式をハード構成で実現した場合のモータ模擬運転制御部１１を示すもので、加算器、乗算器、補正回路、微分回路、２／３回路（３相−２相変換回路）、ＰＷＭ回路１３等により図示のように構成されている。尚、（２）式における _pＬ_d , _pＬ_q は過度項であり、実際の運転においては値が小さいので、本実施の形態では無視される。
【００２９】
図３において、上記入力されたＲ，Ｌ_d ，Ｌ_q 、θ_m （模擬角度センサ信号Ｓθが示す角度：Ｎに対応），φ_a ，Ｌ、及び電圧ｖ_u ′，ｖ_w ′、電流ｉ_u ，ｉ_w を用いて図示の各演算が行われる。これにより、相電圧指令Ｖ_ou ^* ，Ｖ_ov ^* ，Ｖ_ow ^* を生成し、これに基づいてＰＷＭ回路１３よりインバータ２のゲート信号が生成される。
【００３０】
図３において、ｉ_u ，ｉ_w をθ_m を角度補正した値に基づいて３相−２相変換して直交２軸上のｉ_d ，ｉ_q を得ると共に、ｖ_u ′，ｖ_w ′をθ_m を角度補正した値に基づいて３相−２相変換してｖ_d ，ｖ_q を得る。また、Ｌ_d ，Ｌ_q と実際のＬとの差分を求め、この差分とＲ，ｉ_d ，ｉ_q に基づいてｖ_d ^* ，ｖ_q ^* を求める。このｖ_d ^* ，ｖ_q ^* と実際のｖ_d ，ｖ_q とを突き合わせ、その結果を θ_mを角度補正した値に基づいて２相−３相変換することにより、Ｖ_ou ^* ，Ｖ_ov ^* ，Ｖ_ow ^* が得られる。
この第１の実施の形態では、フィルタ７、７Ａ，７Ｂのインダクタンスを、模擬の対象とするモータの内部インダクタンスに略等しくしたので、ＰＷＭに起因する電流リップルが正確に再現される。従って、この電流リップルに起因するインバータの発熱などの影響を模擬することが可能になる。
【００３１】
次に、本実施の形態の第２の実施の形態について説明する。
上述した第１の実施の形態では、モータ回転数Ｎ（θ_m ）を予め設定して制御を行っているが、Ｎを設定せずに、インバータ１の出力電流・電圧からモータトルクを計算し、そのトルクと試験で想定する機械のイナーシャ（重量相当等）からＮ（θ_m ）を算出して制御に用いることにより、モータの加減速時の状態を模擬することができる。
即ち、モータが停止している状態からインバータ１が動作して加速していくとき、どのように加速していくのかは、どのようなパターンで電流・電圧が加えられたかによって決まる。
【００３２】
例えば、電気自動車を駆動するモータの場合、モータ模擬運転制御部１１により、入力される出力電圧・電流（ｖ_u ′，ｖ_w ′，ｉ_u ，ｉ_w ）によりとれだけトルクが出ているかを計算することができ、そのトルクに応じてどのように加速していくのかを、車体の重さ等からモータ軸換算でのイナーシャが分かっていれば、走行抵抗等を考慮して計算することができる。
【００３３】
即ち、計算したトルクとイナーシャ、走行抵抗等から、どれだけ加速すればどれだけの回転数Ｎとなり、次にどれだけの回転数Ｎとなるかを計算し、そのＮに基づいて模擬角度センサ信号Ｓθを作ってインバータ１にフィードバックすることにより、実際にモータを加減速している状態で様々な試験を行うことができる。
従って、本実施の形態の場合は、モータ模擬運転制御部１１には、車体重量やイナーシャ、走行抵抗等の機械的定数が入力設定される。
【００３４】
図４は本発明の第３の実施の形態によるインバータ試験装置を示すもので、電圧制御方式の場合を示している。図４においては、図１と対応する部分には同一番号を付して重複する説明は省略する。
図４において、制御回路２０は、電圧指令と周波数指令に応じて所定の電流変換式を用いて被試験インバータ１を出力電圧を所定の値に制御する。
【００３５】
また、モータ模擬運転制御部１１において、インバータ１の出力電圧ｖ_u ，ｖ_w から電圧位相検出回路２１により電圧位相θを検出する。また、出力電流ｉ_u ，ｉ_w をθに基づいて３相−２相変換してｉ_d ，ｉ_q を得る。このｉ_d ，ｉ_q と、負荷指令に基づいて決定される電流の振幅・位相を持つｉ_d ^* ，ｉ_q ^* とが突き合わされてｖ_d ^* ，ｖ_q ^* が得られる。このｖ_d ^* ，ｖ_q ^* がθに基づいて２相−３相変換されることにより、相電圧指令Ｖ_ou ^* ，Ｖ_ov ^* ，Ｖ_ow ^* が得られる。そして、この相電圧指令に基づいてＰＷＭ回路２２によりインバータ２のゲート信号を生成することができる。
【００３６】
本実施の形態によれば、インバータ１の出力電圧が所定の値の状態において、出力電圧の振幅・位相が所望となるようにインバータ２の出力電流の振幅・位相を制御することにより、インバータ１にモータが接続されているのと同等の状態でインバータ１の試験を行うことができ、モータの任意の運転条件に応じて任意の負荷インピーダンスを設定して、インバータ１の試験を行うことができる。
【００３７】
尚、上述した各実施の形態は、ＩＰＭモータを負荷とした場合について説明したが、電圧方程式があれば、ＩＭモータ（誘導電動機）、ＳＰＭ（表面磁石同期）モータ等々どのようなモータでも模擬運転可能である。
【００３８】
また、第４の実施の形態として、図１に示すように、モータ模擬運転制御部１において、第１のインバータ１の出力電圧・電流とモータ定数からモータのトルク、速度、回転位置、損失効率、温度等を計算して、表示又は出力するように構成してもよい。
【００３９】
（変形例）
以下、上述の第１ないし第４の実施の形態の変形例を説明する。
上述の各実施の形態では、フィルタ７が特定のモータの内部インダクタンスに相当するものとしたので、模擬の対象が特定のモータに制約されることになる。そこで、以下に説明する変形例では、模擬の対象とするモータの内部インダクタンスに応じてフィルタ７のインダクタンスを調整可能とし、上述の制約を回避する。尚、一般には、インダクタは、誘導性を有するものを表し、インダクタンスはその値を表すが、ここでは説明の便宜上、これらの用語の意味は一般的な定義に従うものとしながらも、インダクタとインダクタンスとを同一の符号で表す。
【００４０】
図６に、フィルタ７の第１の変形例として、インダクタンスの調整が可能なフィルタ７Ａの構成を示す。このフィルタ７Ａは、ｕ相、ｖ相、ｗ相の各相について、模擬の対象とするモータのインダクタンスに応じた複数のインダクタを切り替え可能に備える。具体的には、ｕ相について２つのインダクタＬ_u1，Ｌ_u2が設けられ、スイッチＳＷ_u1，ＳＷ_u2によって何れかが選択される。同様に、ｖ相についてはインダクタＬ_v1，Ｌ_v2が設けられ、ｗ相についてはインダクタＬ_w1，Ｌ_w2が設けられる。
【００４１】
ここで、インダクタンスＬ_u1，Ｌ_v1，Ｌ_w1の組と、インダクタンスＬ_u2，Ｌ_v2，Ｌ_w2の組は、異なる２つのモータの内部インダクタンスにそれぞれ相当するものであり、これらインダクタンスの組は、スイッチＳＷ_u1，ＳＷ_v1，ＳＷ_w1の組およびスイッチＳＷ_u2，ＳＷ_v2，ＳＷ_w2の組によりそれぞれ選択される。何れを選択するかは模擬の対象とするモータの内部インダクタンスにより決定され、モータの内部インダクタンスに等しいインダクタンスの組が選択される。
この第１の変形例によれば、インダクタを選択することにより、電気的特性の異なる２機のモータを模擬の対象とすることができ、各モータの各電流波形を正確に再現することができる。また、選択するインダクタの数を増やすことにより、模擬の対象とするモータの種類を任意に増やすことができる。
【００４２】
図７に、第２の変形例を示す。同図に示すフィルタ７Ｂは、模擬の対象となるモータに応じてインダクタンスを変更するためのタップを備える。即ち、ｕ相が供給されるインダクタＬ_uは、模擬の対象となる複数のモータのうち、最大インダクタンスを有するモータを想定して設定される。この例では、最大インダクタンスを有するモータの内部インダクタンスと等しく設定される。インダクタＬ_uの始端寄りの中点と終端寄りの中点にはタップＴ_uaおよびＴ_ubがそれぞれ設けられ、終端部にはタップＴ_ucが設けられる。
【００４３】
各タップの位置は、インダクタンスＬ_uの始端と各タップとの間のインダクタンスが、模擬の対象とする各モータの内部インダクタンスに等しくなるように設定される。端子Ｓはトランス８の１次側に接続される。タップＴ_ua，Ｔ_ub，Ｔ_ucのうち、模擬の対象とするモータのインダクタンスに相当するものが端子Ｓｕに選択的に接続される。残りのｖ相、ｗ相のインダクタＬ_vおよびインダクタＬ_wについても、上述のｕ相と同様に、タップＴ_ua，Ｔ_ub，Ｔ_ucおよびタップＴ_va，Ｔ_vb，Ｔ_vcがそれぞれ設けられ、端子Ｓ_vおよび端子Ｓ_wに選択的に接続される。
【００４４】
従って、この第２の変形例によれば、タップを選択することにより、電気的特性の異なる３機のモータを模擬の対象とすることができ、各モータの各電流波形を正確に再現することができる。また、選択するタップ数を増やすことにより、模擬の対象とするモータの種類を任意に増やすことができる。さらに、１つのインダクタを共用して複数のモータの内部インダクタンスを再現するので、装置の大型化やコストの上昇を有効に抑えることができる。
【００４５】
【発明の効果】
以上説明したように本発明によれば、モータを実際に使用することなく、モータの動作を模擬的に行いながらインバータの試験を行うことができる。また、従来のＲ−Ｌ負荷の切り換えではできなかった回生運転試験を行うことができる。また、Ｒ−Ｌ負荷の切り換えの場合に比べて装置の大幅な省エネルギー化が可能となる。さらに、電流制御の場合、被試験インバータの電圧、力率の調整が可能となる。
また、被試験インバータと疑似負荷用インバータとの間にトランスを設けたことにより、被試験インバータにおける中性点電圧の変動による影響をなくし、良好な制御を行うことができる。
【図面の簡単な説明】
【図１】 本発明の第１の実施の形態による電流制御方式のインバータ試験装置を示す回路構成図である。
【図２】 図１におけるトランス８を設けた理由を説明するための構成図である。
【図３】 電流制御方式におけるモータ模擬運転制御部のハード構成例を示す構成図である。
【図４】 本発明の第３の実施の形態による電圧制御方式のインバータ試験装置のハード構成例を示す構成図である。
【図５】 従来のインバータ試験装置の一例を示す構成図である。
【図６】 本発明の実施の形態に係るフィルタの第１の変形例を示す図である。
【図７】 本発明の実施の形態に係るフィルタの第２の変形例を示す図である。
【符号の説明】
１ 被試験インバータ
２ 疑似負荷用インバータ
７，７Ａ，７Ｂ フィルタ
８ トランス
９ フィルタ
１０ 変流器
１１ モータ模擬運転制御部
１２ 角度センサ模擬制御部
１３、２２ ＰＷＭ回路
Ｌ_u1，Ｌ_u2，Ｌ_v1，Ｌ_v2，Ｌ_w1，Ｌ_w2 インダクタンス（インダクタ）
ＳＷ_u1，ＳＷ_u2，ＳＷ_v1，ＳＷ_v2，ＳＷ_w1，ＳＷ_w2 スイッチ
Ｌ_u，Ｌ_v，，Ｌ_w インダクタンス（インダクタ）
Ｔ_ua，Ｔ_ub，Ｔ_uc，Ｔ_va，Ｔ_vb，Ｔ_vc，Ｔ_wa，Ｔ_wb，Ｔ_wc タップ
Ｓ_u，Ｓ_v，Ｓ_w 端子[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inverter test apparatus for testing an inverter having a motor as a load.
[0002]
[Prior art]
FIG. 5 is a circuit configuration diagram showing an example of a conventional inverter test apparatus using a motor as a load.
In FIG. 5, a pseudo load circuit 200 including 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.
[0003]
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, a predetermined current of amplitude _ic flows at an angle θ _m + θ _c corresponding to the operating condition with respect to the angle θ _m (phase) indicating the position of the motor rotor detected by the angle sensor 300. The inverter under test 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 θ _m can be obtained. From 300, a simulated angle sensor signal Sθ corresponding to θ _m is generated.
[0004]
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.
[0005]
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.
[0006]
[Problems to be solved by the invention]
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. In order to be able to cope with various operating conditions in the power running operation, the R, L constituting the pseudo load circuit 200 is configured. , 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.
[0007]
The present invention has been made to solve the above problem, and it is an object of the present invention to test an inverter by simulating the operation of a motor without actually connecting the motor.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, an inverter test apparatus according to the present invention has a second inverter serving as a pseudo load for a first inverter to be tested and an AC output of the first inverter input to the primary side. , The transformer to which the AC output of the second inverter is input to the secondary side, the operating conditions and motor characteristics set for the motor that is the actual load of the first inverter, and the detected output voltage of the first inverter Control means for simulating the operation of the motor by generating a first control signal for controlling the first inverter and a second control signal for controlling the second inverter based on either or both of the currents; said first inverter has a voltage command, a controlled output voltage based on the frequency command to a predetermined value, said control means, the load and the output voltage and frequency of the first inverter It is obtained so as to control the amplitude and phase of the second inverter output voltage based on the amplitude and phase of the current by decree.
[0009]
Therefore, according to the present invention, the operating conditions such as the number of revolutions of the motor and the motor characteristics such as the motor constant are set in the control means, the output current / voltage of the first inverter is detected, and the control means By controlling the second inverter based on the conditions, motor characteristics and output current / voltage, it is possible to simulate the same operating state as when the motor is connected without connecting the actual motor. .
According to the present invention, the first inverter is controlled to a predetermined value based on the voltage command and the frequency command, and the control means includes the output voltage / frequency of the first inverter and the load. The amplitude / phase of the output voltage of the second inverter is controlled based on the amplitude and phase of the current by the command. Thereby, the load test by the current control method becomes possible.
[0010]
In addition, the second inverter serving as a pseudo load for the first inverter under test and the AC output of the first inverter are input to the primary side, and the AC output of the second inverter is input to the secondary side. The first inverter based on one or both of the operating conditions and motor characteristics set for the transformer and the motor that is the actual load of the first inverter and the detected output voltage / current of the first inverter. By generating a first control signal to be controlled and a second control signal for controlling the second inverter, the control means for simulating the operation of the motor, and the outputs of the first and second inverters are PWM signals. There has, a filter corresponding to the inductance of the motor between the first inverter and the transformer, the filter response to the inductance of the motor to be simulated Taps for changing the inductance of the filter is provided with a plurality Te, the position of the tap, inductance, set equal to the internal inductance of the motor and the simulated target between beginning and each tap of the inductance The first inverter is controlled to a predetermined value based on the voltage command and the frequency command, and the control means is configured to control the output voltage / frequency of the first inverter and the current based on the load command. The amplitude and phase of the output voltage of the second inverter are controlled based on the amplitude and phase .
[0012]
Furthermore, the outputs of the first and second inverters are PWM signals, and a filter corresponding to the inductance of the motor is provided between the first inverter and the transformer. Thereby, the waveform of the PWM signal is converted into a sine wave, and the current waveform of the motor can be reproduced.
Furthermore, the torque, speed, rotational position, loss, efficiency, temperature, etc. of the motor are calculated from the output voltage / current of the first inverter and the motor constant, and displayed or output. Thereby, it becomes possible to grasp the operating state of the motor to be simulated.
[0013]
Furthermore, the filter includes a plurality of inductors that can be switched according to the inductance of the motor to be simulated. Thereby, if the thing according to the internal inductance of the motor is selected from the plurality of inductances, each current waveform when the plurality of motors are used as loads is reproduced. Therefore, a plurality of motors can be simulated.
Furthermore, the filter includes a tap for changing the inductance of the filter according to the inductance of the motor to be simulated. Thereby, if the thing according to the internal inductance of the motor is selected from the plurality of taps, each current waveform when a plurality of motors are used as loads is reproduced. Accordingly, a plurality of motors can be simulated as well.
Furthermore, the filter has an inductance substantially equal to the inductance of the motor. As a result, the PWM signal is converted into a waveform by an inductance equal to the inductance of the motor, so that a current waveform substantially equal to the current waveform of the motor to be simulated can be reproduced.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a circuit configuration diagram showing an inverter test apparatus according to a first embodiment 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.
[0015]
In FIG. 1, an AC voltage from a commercial AC power supply 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 an inverter 1. The DC voltage is also supplied to the inverter 2. A PWM ₁ signal as a PWM-modulated rectangular wave voltage is output from the AC output terminal of the inverter 1. This PWM ₁ 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. A PWM ₂ signal is output from the AC output terminal of the inverter 2 as a PWM-modulated rectangular wave voltage. From this PWM ₂ signal, a sine wave of a fundamental wave is extracted 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. In the first embodiment, the inductance of the filter 7 is approximately equal to the inductance of the motor that is the actual load of the inverter 1. However, “equal” as used herein means to include an inductance difference that does not cause a significant difference in the effect on the motor as a load. Of course, the word “equivalent” is also included.
[0016]
The U-phase and W-phase currents i _u and i _w (controlled to a predetermined value by the current control method) of the PWM ₁ signal output from the inverter 1 are detected by the current transformer 10 to control the motor simulation operation. Part 11 is added. Further, sinusoidal voltages v _u ′, v _w ′ obtained from the PWM ₁ signal through the filter 7 are detected and applied to the motor simulation operation control unit 11.
[0017]
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 constant in the case of the IPM motor includes the armature resistance R of the motor, the motor inductance L _d on the d axis on the d and q orthogonal coordinate axes on the motor stator, the motor inductance L _q on the q axis, and the motor induced voltage. The constant φ _a and the inductance L of the filter 7 are input. The motor simulation operation control unit 11 is provided with an angle sensor simulation control unit 12.
[0018]
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.
[0019]
Therefore, according to the present embodiment, by controlling the amplitude and phase of the output voltage of the inverter 2 as a pseudo load, the motor that is 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.
[0020]
Next, an actual test operation will be described.
When testing the inverter 1 by the current control method, the output currents i _u and i _w 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.
The motor simulation operation control unit 11 is input and set by the operator with the above-described operation condition N and motor constants R, L _d , L _q , L, and φ _a . 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.
[0021]
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, motor constants R, L _d , L _q , L, and φ _a , and the inverter 2 Operates according to the signal. 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 looking at the output currents i _u and i _w and the output voltages v _u ′ and v _w ′ of the inverter 1. The amplitude and phase of the output voltages v _u ′ and v _w ′ are determined by the load.
[0022]
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.
[0023]
Next, in the present embodiment, by providing the transformer 8 between the inverter 1 and the inverter 2, it is possible to eliminate the influence of the neutral point fluctuation of the three-phase output voltage of the inverter 1 and perform good control. I have to.
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. varying the neutral voltage by changing circuit 15, the current i _x between the inverter 1 and the inverter 2 may flow through the influence. It is difficult to control this current i _x to zero. Therefore, in this embodiment, by providing the transformer 8, and so as to cut off the current i _x.
[0024]
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 v _u ′ and v _w ′ of the transformer 8 are detected. Here, since the inductance of the filter 7 is set to be substantially equal to the inductance of the motor serving as the actual load, the voltages (v _u ′, v _w ′, etc.) supplied from the filter 7 to the primary side of the transformer 8 are actually Therefore, it is possible to faithfully reproduce the waveform to be supplied to the load. Based on the primary side voltage and currents i _u and i _w of the transformer 8, the output voltage v _u of the inverter 1 is calculated by the following equation.
v _u = L · i _u + v _u '------ (1)
[0025]
If the load is an IPM motor,
[0026]
[Expression 1]

[0027]
Control is performed so as to satisfy the voltage equation. In the formula (2),
V _d , V _q : d, q axis armature voltage, i _d , i _q : d, q axis armature current, R: armature resistance, L _d , L _q : d, q axis inductance, ω _m : Angular velocity (corresponding to N), p: d / dt, φ _a : maximum value of armature flux linkage by permanent magnet × (square root of 3/2), p _n : number of pole pairs. T is the output torque T = [p _n {φ _a i _q + (L _d −L _q ) i _d i _q } ------ (3)
It is.
[0028]
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 _p L _d and _p L _q in equation (2) are excessive terms and are negligible in the present embodiment because the values are small in actual operation.
[0029]
In FIG. 3, the input R, L _d , L _q , θ _m (angle corresponding to the simulated angle sensor signal Sθ: corresponding to N), φ _a , L, voltages v _u ′, v _w ′, current i _u, the operation illustrated with reference to i _w is performed. Thereby, phase voltage commands V _ou ^* , V _ov ^* , V _ow ^* are generated, and the gate signal of the inverter 2 is generated from the PWM circuit 13 based on the phase voltage commands V _ou ^* , V _ov ^* , V _ow ^* .
[0030]
In FIG. 3, i _u and i _w are subjected to three-phase to two-phase conversion based on a value obtained by correcting θ _m to obtain i _d and i _q on two orthogonal axes, and v _u ′ and v _w ′ are v _d and v _q are obtained by performing three-phase to two-phase conversion based on the angle-corrected value of θ _m . Further, the difference between L _d and L _q and the actual L is obtained, and v _d ^* and v _q ^* are obtained based on this difference and R, i _d and i _q . This v _d ^* , v _q ^* is matched with the actual v _d , v _q, and the result is subjected to two-phase to three-phase conversion based on a value obtained by angle-correcting θ _m to obtain V _ou ^* , V _ov ^*. , V _ow ^* is obtained.
In the first embodiment, since the inductances of the filters 7, 7A, 7B are substantially equal to the internal inductance of the motor to be simulated, the current ripple caused by the PWM is accurately reproduced. Therefore, it becomes possible to simulate the influence of heat generation of the inverter caused by this current ripple.
[0031]
Next, a second embodiment of the present embodiment will be described.
In the first embodiment described above, control is performed by setting the motor rotation speed N (θ _m ) in advance, but without setting N, the motor torque is calculated from the output current / voltage of the inverter 1. By calculating N (θ _m ) from the torque and the inertia (equivalent to weight, etc.) of the machine assumed in the test and using it for control, the motor acceleration / deceleration state can be simulated.
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.
[0032]
For example, in the case of a motor that drives an electric vehicle, the motor simulation operation control unit 11 determines whether the torque is generated by the output voltage / current (v _u ′, v _w ′, i _u , i _w ) input. If the inertia in terms of the motor shaft is known from the weight of the vehicle body, it is possible to calculate how to accelerate according to the torque considering the running resistance etc. it can.
[0033]
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.
[0034]
FIG. 4 shows an inverter test apparatus according to the third embodiment of the present invention, and shows a case of a voltage control system. In FIG. 4, parts corresponding to those in FIG.
In FIG. 4, the control circuit 20 controls the output voltage of the inverter under test 1 to a predetermined value using a predetermined current conversion equation in accordance with the voltage command and the frequency command.
[0035]
In the motor simulation operation control unit 11, the voltage phase θ is detected by the voltage phase detection circuit 21 from the output voltages v _u and v _w of the inverter 1. Further, the output currents i _u and i _w are subjected to three-phase to two-phase conversion based on θ to obtain i _d and i _q . These i _d and i _q are matched with i _d ^* and i _q ^* having the current amplitude and phase determined based on the load command to obtain v _d ^* and v _q ^* . The v _d ^* and v _q ^* are subjected to two-phase to three-phase conversion based on θ, whereby phase voltage commands V _ou ^* , V _ov ^* , and V _ow ^* are obtained. The gate signal of the inverter 2 can be generated by the PWM circuit 22 based on this phase voltage command.
[0036]
According to the present embodiment, in the state where the output voltage of the inverter 1 is a predetermined value, the amplitude / phase of the output current of the inverter 2 is controlled so that the amplitude / phase of the output voltage becomes desired, whereby the inverter 1 The inverter 1 can be tested in a state equivalent to the motor being connected to the inverter 1, and the inverter 1 can be tested by setting an arbitrary load impedance according to an arbitrary operating condition of the motor. .
[0037]
In each of the above-described embodiments, the case where an IPM motor is used as a load has been described. However, if there is a voltage equation, any motor such as an IM motor (induction motor) or an SPM (surface magnet synchronous) motor can be simulated. Is possible.
[0038]
As a fourth embodiment, as shown in FIG. 1, in the motor simulation operation control unit 1, the motor torque, speed, rotational position, and loss efficiency are calculated from the output voltage / current of the first inverter 1 and the motor constant. The temperature may be calculated and displayed or output.
[0039]
(Modification)
Hereinafter, modifications of the first to fourth embodiments will be described.
In each of the above-described embodiments, the filter 7 corresponds to the internal inductance of a specific motor. Therefore, the simulation target is limited to the specific motor. Therefore, in the modification described below, the inductance of the filter 7 can be adjusted according to the internal inductance of the motor to be simulated, thereby avoiding the above-described restrictions. In general, an inductor represents an inductive element and an inductance represents a value thereof. For convenience of explanation, the meaning of these terms follows a general definition, but the inductor, the inductance, Are represented by the same symbols.
[0040]
FIG. 6 shows a configuration of a filter 7 </ b> A capable of adjusting the inductance as a first modification of the filter 7. This filter 7A includes a plurality of inductors that can be switched in accordance with the inductance of the motor to be simulated for each of the u-phase, v-phase, and w-phase. Specifically, two inductors L _u1 and L _u2 are provided for the u phase, and one of them is selected by the switches SW _u1 and SW _u2 . Similarly, inductors L _v1 and L _v2 are provided for the v phase, and inductors L _w1 and L _w2 are provided for the w phase.
[0041]
Here, the set of inductances L _u1 , L _v1 , L _{w1 and} the set of inductances L _u2 , L _v2 , L _w2 correspond to the internal inductances of two different motors, respectively. The switches SW _u1 , SW _v1 , SW _w1 and the switches SW _u2 , SW _v2 , SW _w2 are selected. Which is selected is determined by the internal inductance of the motor to be simulated, and an inductance set equal to the internal inductance of the motor is selected.
According to the first modification, by selecting an inductor, two motors having different electrical characteristics can be simulated, and each current waveform of each motor can be accurately reproduced. . Also, by increasing the number of inductors to be selected, the types of motors to be simulated can be arbitrarily increased.
[0042]
FIG. 7 shows a second modification. The filter 7B shown in the figure includes a tap for changing the inductance according to the motor to be simulated. That is, the inductor L _u supplied with the u phase is set assuming a motor having the maximum inductance among a plurality of motors to be simulated. In this example, it is set equal to the internal inductance of the motor having the maximum inductance. The inductor L _u start end side of the midpoint tap T _ua and T _ub is the midpoint of the end near are respectively provided, the tap T _uc is provided in the end portion.
[0043]
The position of each tap, inductance between the beginning and each tap of the inductance L _u is set equal to the internal inductance of the motor to be subjected to simulated. The terminal S is connected to the primary side of the transformer 8. Of the taps T _ua , T _ub , T _uc , one corresponding to the inductance of the motor to be simulated is selectively connected to the terminal Su. The remaining v-phase and w-phase inductors L _v and L _w are also provided with taps T _ua , T _ub , T _uc and taps T _va , T _vb , T _vc , respectively, similarly to the u phase described above. The terminal _Sv and the terminal _Sw are selectively connected.
[0044]
Therefore, according to the second modification, by selecting a tap, three motors having different electrical characteristics can be simulated, and each current waveform of each motor can be accurately reproduced. Can do. Also, by increasing the number of taps to be selected, the types of motors to be simulated can be arbitrarily increased. Furthermore, since the internal inductance of a plurality of motors is reproduced by sharing one inductor, it is possible to effectively suppress an increase in size and cost of the device.
[0045]
【The invention's effect】
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 to perform good control.
[Brief description of the drawings]
FIG. 1 is a circuit configuration diagram showing an inverter test apparatus of a current control system according to a first embodiment of the present invention.
2 is a configuration diagram for explaining the reason for providing a transformer 8 in FIG. 1; FIG.
FIG. 3 is a configuration diagram illustrating a hardware configuration example of a motor simulation operation control unit in a current control method.
FIG. 4 is a block diagram showing a hardware configuration example of a voltage control type inverter test apparatus according to a third embodiment of the present invention.
FIG. 5 is a configuration diagram showing an example of a conventional inverter test apparatus.
FIG. 6 is a diagram showing a first modification of the filter according to the embodiment of the present invention.
FIG. 7 is a diagram showing a second modification of the filter according to the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Inverter to be tested 2 Pseudo load inverter 7, 7A, 7B Filter 8 Transformer 9 Filter 10 Current transformer 11 Motor simulation operation control unit 12 Angle sensor simulation control unit 13, 22 PWM circuit L _u1 , L _u2 , L _v1 , L _v2 , _Lw1 , _Lw2 inductance (inductor)
_{SW u1, SW u2, SW v1} , SW v2, SW w1, SW w2 switch L _u, L _v ,, L _w inductance (inductor)
_{T ua, T ub, T uc} , T va, T vb, T vc, T wa, T wb, T wc tap S _u, S _v, S _w terminal

Claims (7)

A second inverter serving as a pseudo load for the first inverter under test;
A transformer in which the AC output of the first inverter is input to the primary side and the AC output of the second inverter is input to the secondary side;
A first inverter that controls the first inverter based on one or both of the operating conditions and motor characteristics set for the motor that is the actual load of the first inverter and the detected output voltage / current of the first inverter. And a control means for simulating the operation of the motor by generating the control signal and the second control signal for controlling the second inverter ,
The first inverter has an output voltage controlled to a predetermined value based on a voltage command and a frequency command. An inverter test apparatus for controlling the amplitude and phase of the output voltage of the second inverter based on the second inverter . A second inverter serving as a pseudo load for the first inverter under test;
A transformer in which the AC output of the first inverter is input to the primary side and the AC output of the second inverter is input to the secondary side;
A first inverter that controls the first inverter based on one or both of the operating conditions and motor characteristics set for the motor that is the actual load of the first inverter and the detected output voltage / current of the first inverter. A control means for simulating the operation of the motor by generating a control signal for the second inverter and a second control signal for controlling the second inverter;
The outputs of the first and second inverters are PWM signals, and a filter corresponding to the inductance of the motor is provided between the first inverter and the transformer.
The filter is provided with a plurality of taps for changing the inductance of the filter in accordance with the inductance of the motor to be simulated, and the position of the tap is simulated by the inductance between the inductance start point and each tap. It is set to be equal to the internal inductance of each target motor,
The first inverter has an output voltage controlled to a predetermined value based on a voltage command and a frequency command. An inverter test apparatus for controlling the amplitude and phase of the output voltage of the second inverter based on the second inverter . The first output of the second inverter are PWM signals, the inverter testing according to claim 1, characterized in that a filter corresponding to the inductance of the motor between the first inverter and the transformer apparatus. The first output voltage and current and the motor constant of the motor torque of the inverter, the speed, the rotational position, the loss, efficiency, to calculate the temperature and the like, among of claims 1 to 3, characterized in that display or output The inverter test apparatus according to any one of the above. The inverter test apparatus according to claim 3 , wherein the filter includes a plurality of inductors that can be switched according to the inductance of a motor to be simulated. The inverter test apparatus according to claim 3, wherein the filter includes a tap for changing the inductance of the filter according to the inductance of the motor to be simulated. The inverter test apparatus according to claim 2, wherein the filter has an inductance substantially equal to an inductance of the motor.

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