JP7191176B1 - Power conversion device, generator motor control device, and electric power steering device - Google Patents

Abstract

A power conversion device, a control device for a generator-motor, and an electric power steering device capable of further reducing phase current ripple are obtained. A first offset calculator (8a) multiplies the central value of three applied voltages corresponding to three phases in a first applied voltage and the central value of three applied voltages corresponding to three phases in a second applied voltage by K1. are equal to each other, the first offset voltage is subtracted from the first voltage command. The second offset calculator 8b is configured so that the central value of the three applied voltages corresponding to the three phases in the first applied voltage and the central value of the three applied voltages corresponding to the three phases in the second applied voltage are equal to K1 times. Then, the second offset voltage is subtracted from the second voltage command. When the phase of the first reference signal and the phase of the second reference signal are equal, K1 is "1", and when the phase of the first reference signal and the phase of the second reference signal differ by 180 degrees, K1 is "- 1”. [Selection drawing] Fig. 1

Description

The present disclosure relates to a power conversion device, a control device for a generator motor, and an electric power steering device.

In a conventional power converter, voltage is applied to two winding sets using two inverters. Also, when the third harmonic is superimposed on the voltage command, each carrier signal in the two inverters is offset by 90 degrees from each other to avoid that the two inverters become effective voltage vectors at the same time (e.g., patent Reference 1).

JP 2012-50252 A

In the conventional power conversion device as described above, due to the mutual inductance of the two winding sets, when the first set is outputting an effective voltage vector, the current change of the second set occurs, and the second set is effective. A first set of current changes occurs when outputting a voltage vector. For this reason, the conventional power converter has a problem that the phase current ripple becomes large.

The present disclosure has been made in order to solve the above-described problems, and aims to obtain a power conversion device, a control device for a generator motor, and an electric power steering device that can further reduce the phase current ripple. aim.

A power conversion device according to the present disclosure has a plurality of first switching elements, converts a DC voltage from a DC power supply into a first AC voltage, and applies it to a first three-phase winding of an AC rotating machine. A first power converter, a second power converter having a plurality of second switching elements, converting a DC voltage into a second AC voltage, and applying the voltage to a second three-phase winding of an AC rotary machine; By comparing the first applied voltage obtained by subtracting the first offset voltage as the third harmonic signal from the first voltage command, which is the voltage command for the first three-phase winding, with the first reference signal , calculating a plurality of first on/off signals for a plurality of first switching elements, and subtracting a second offset voltage as a third harmonic signal from a second voltage command, which is a voltage command for a second three-phase winding; A control unit that calculates a plurality of second on/off signals for the plurality of second switching elements by comparing the second applied voltage obtained by the above with a second reference signal, The first voltage command to the first offset voltage so that the central value of the three applied voltages corresponding to the three phases and the central value of the three applied voltages corresponding to the three phases in the second applied voltage are equal to K ₁ times is subtracted and the second offset voltage is subtracted from the second voltage command, the first reference signal and the second reference signal are carrier wave signals, and the phase of the first reference signal and the phase of the second reference signal are equal , K ₁ is 1, and K ₁ is −1 if the phase of the first reference signal and the phase of the second reference signal differ by 180 degrees.

According to the power conversion device, generator motor control device, and electric power steering device according to the present disclosure, the phase current ripple can be further reduced.

1 is a configuration diagram showing a power converter according to Embodiment 1; FIG. FIG. 2 is a diagram showing the relationship between the phase of the first three-phase winding and the phase of the second three-phase winding in FIG. 1; Figure 2 shows a first voltage vector output by the first power converter of Figure 1; It is a figure which shows the relationship between several 1st on-off signals and the 1st voltage vector output by a 1st power converter. Figure 2 shows a second voltage vector output by the second power converter of Figure 1; It is a figure which shows the relationship between several 2nd on-off signals and the 2nd voltage vector output by a 2nd power converter. FIG. 4 is a diagram showing a waveform of a first voltage command; FIG. It is a figure which shows the waveform of a 1st offset voltage. It is a figure which shows the waveform of a 1st applied voltage. 3 is a diagram for explaining the operation of the first on/off signal generator of FIG. 1; FIG. 3 is a diagram for explaining the operation of the second on/off signal generator of FIG. 1; FIG. FIG. 4 is a diagram showing the relationship between on/off timings of a first high potential side switching element and output voltage vectors; FIG. 10 is a diagram showing the relationship between the on/off timing of the second high potential side switching element and the output voltage vector; FIG. 5 is a diagram showing a relationship between a coupling coefficient and a sum of squares of DC components of differential values of six-phase currents; FIG. 4 is a diagram showing the relationship between on/off timings of a first high potential side switching element and output voltage vectors; FIG. 10 is a diagram showing the relationship between the on/off timing of the second high potential side switching element and the output voltage vector; 3 is a diagram for explaining the operation of the first on/off signal generator of FIG. 1; FIG. FIG. 2 is a configuration diagram showing an application example of the power conversion device of FIG. 1 to a generator motor; FIG. 2 is a configuration diagram showing an application example of the power conversion device of FIG. 1 to an electric motor for an electric power steering device; FIG. 2 is a configuration diagram showing a power conversion device according to Embodiment 2; FIG. 10 is a configuration diagram showing a power conversion device according to Embodiment 3; FIG. 11 is a configuration diagram showing a power conversion device according to Embodiment 4; FIG. 11 is a configuration diagram showing a power converter according to Embodiment 5; 24 is a diagram showing a first voltage vector and a second voltage vector output by the power converter of FIG. 23; FIG. FIG. 5 is a diagram showing the relationship between the on/off timing of the first high potential side switching element and the output voltage vector when the central value of the first applied voltage is 0; FIG. 10 is a diagram showing the relationship between the on/off timing of the second high potential side switching element and the output voltage vector when the center value of the second applied voltage is 0; FIG. 5 is a diagram showing a relationship between a coupling coefficient and a sum of squares of DC components of differential values of six-phase currents; FIG. 4 is a diagram showing a first example of a combination of a first voltage vector and a second voltage vector in a voltage phase range of 0 degrees to 60 degrees; FIG. 10 is a diagram showing a second example of a combination of a first voltage vector and a second voltage vector in a voltage phase range of 0 degrees to 60 degrees; FIG. 4 is a diagram showing a first example of switching of carrier signals according to voltage phase; FIG. 11 is a diagram showing a third example of a combination of the first voltage vector and the second voltage vector in the voltage phase range from 0 degrees to 60 degrees; FIG. 10 is a diagram illustrating a second example of switching of carrier signals according to voltage phase; FIG. 10 is a diagram illustrating a third example of switching of carrier signals according to voltage phase; FIG. 2 is a configuration diagram showing a first example of a processing circuit that implements the functions of the power converters of the first to fifth embodiments; FIG. 5 is a configuration diagram showing a second example of a processing circuit that implements the functions of the power converters of the first to fifth embodiments;

Embodiments will be described below with reference to the drawings.
Embodiment 1.
FIG. 1 is a configuration diagram showing a power converter according to Embodiment 1. FIG. The power converter includes a smoothing capacitor 3 , a first power converter 4 a , a second power converter 4 b , a first current detector 5 a , a second current detector 5 b and a controller 6 .

An AC rotating machine 1 as a load and a DC power supply 2 as a power supply are connected to the power converter. The power converter converts the DC voltage Vdc from the DC power supply 2 into an AC voltage and applies it to the AC rotating machine 1 .

The AC rotating machine 1 is a three-phase AC rotating machine. The AC rotating machine 1 has a first three-phase winding and a second three-phase winding. The first three-phase winding and the second three-phase winding are housed in the stator inside the AC rotating machine 1 without being electrically connected to each other. A first three-phase winding includes winding U1, winding V1, and winding W1. The winding U1, the winding V1, and the winding W1 are the U1-phase winding, the V1-phase winding, and the W1-phase winding, respectively. A second three-phase winding includes winding U2, winding V2, and winding W2. Winding U2, winding V2, and winding W2 are the U2-phase winding, the V2-phase winding, and the W2-phase winding, respectively.

Examples of the AC rotating machine 1 include a permanent magnet synchronous rotating machine, an induction rotating machine, and a synchronous reluctance rotating machine. Any of the above rotating machines may be used as the AC rotating machine 1 as long as it has two three-phase windings.

A DC power supply 2 is connected to a first power converter 4a and a second power converter 4b. The DC power supply 2 outputs a DC voltage Vdc to the first power converter 4a and the second power converter 4b. As the DC power supply 2, for example, a battery, a DC-DC converter, a diode rectifier, or a PWM (Pulse Width Modulation) rectifier is used.

The smoothing capacitor 3 is connected in parallel with the DC power supply 2 . That is, one end of the smoothing capacitor 3 is connected to the positive terminal of the DC power supply 2 and the other end of the smoothing capacitor 3 is connected to the negative terminal of the DC power supply 2 . The smoothing capacitor 3 suppresses fluctuations in the bus line current of the first power converter 4a and the second power converter 4b, and stabilizes the DC current. Although not shown, the smoothing capacitor 3 has an equivalent series resistance Rc and a lead inductance Lc in addition to the true capacitor capacitance C. FIG.

The first power converter 4a has a plurality of first switching elements. The first power converter 4 a converts the DC voltage Vdc from the DC power supply 2 into a first AC voltage and applies it to the first three-phase winding of the AC rotary machine 1 . The plurality of first switching elements includes three first high potential side switching elements Sup1, Svp1 and Swp1 and three first low potential side switching elements Sun1, Svn1 and Swn1.

The first high potential side switching elements Sup1, Svp1 and Swp1 correspond to the U1 phase, V1 phase and W1 phase, respectively. The first low potential side switching elements Sun1, Svn1 and Swn1 correspond to the U1 phase, V1 phase and W1 phase, respectively.

The U1-phase first high potential side switching element Sup1 and the U1-phase first low potential side switching element Sun1 are connected in series with each other. The first high potential side switching element Svp1 of the V1 phase and the first low potential side switching element Svn1 of the V1 phase are connected in series with each other. The W1-phase first high potential side switching element Swp1 and the W1-phase first low potential side switching element Swn1 are connected in series with each other. A plurality of first switching elements Sup1 to Swn1 constitute an inverter circuit.

As a result, the U1-phase current Iu1, the V1-phase current Iv1, and the W1-phase current Iw1 flow through the first three-phase winding.

The second power converter 4b has a plurality of second switching elements. The second power converter 4b converts the DC voltage Vdc from the DC power supply 2 into a second AC voltage and applies it to the second three-phase winding of the AC rotating machine 1 . The plurality of second switching elements includes three second high potential side switching elements Sup2, Svp2 and Swp2 and three second low potential side switching elements Sun2, Svn2 and Swn2.

The second high potential side switching elements Sup2, Svp2 and Swp2 correspond to the U2 phase, V2 phase and W2 phase, respectively. The second low potential side switching elements Sun2, Svn2 and Swn2 correspond to the U2 phase, V2 phase and W2 phase, respectively.

The U2-phase second high potential side switching element Sup2 and the U2-phase second low potential side switching element Sun2 are connected in series with each other. The V2-phase second high potential side switching element Svp2 and the V2-phase second low potential side switching element Svn2 are connected in series with each other. The W2-phase second high-potential side switching element Swp2 and the W2-phase second low-potential side switching element Swn2 are connected in series with each other. A plurality of second switching elements Sup2 to Swn2 form an inverter circuit.

As a result, the U2-phase current Iu2, the V2-phase current Iv2, and the W2-phase current Iw2 flow through the second three-phase winding.

A combination of an IGBT (Insulated Gate Bipolar Transistor) and a diode is used for each of the plurality of first switching elements Sup1 to Swn1 and the plurality of second switching elements Sup2 to Swn2. In this combination, an IGBT and a diode are connected in anti-parallel. Also, instead of IGBTs, for example, bipolar transistors or MOS (Metal Oxide Semiconductor) power transistors may be used.

The first current detector 5a is provided between the first power converter 4a and the first three-phase winding. The first current detector 5a detects the values of the U1-phase current Iu1, V1-phase current Iv1, and W1-phase current Iw1 as current detection values Iu1s, Iv1s, and Iw1s, respectively.

The first current detector 5a can constantly detect the values of the U1-phase current Iu1, the V1-phase current Iv1, and the W1-phase current Iw1 regardless of the ON/OFF states of the plurality of first switching elements Sup1 to Swn1. Therefore, the power converter according to the first embodiment can detect each of the first power converter 4a without considering whether the values of the U1-phase current Iu1, the V1-phase current Iv1, and the W1-phase current Iw1 can be detected. It can be determined whether the first switching element is turned on or off.

The second current detector 5b is provided between the second power converter 4b and the second three-phase winding. The second current detector 5b detects the values of the U2-phase current Iu2, V2-phase current Iv2, and W2-phase current Iw2 as current detection values Iu2s, Iv2s, and Iw2s, respectively.

The second current detector 5b can constantly detect the values of the U2-phase current Iu2, the V2-phase current Iv2, and the W2-phase current Iw2 regardless of the ON/OFF states of the plurality of second switching elements Sup2 to Swn2. Therefore, the power converter according to Embodiment 1 can detect each of the second power converter 4b without considering whether the values of the U2-phase current Iu2, the V2-phase current Iv2, and the W2-phase current Iw2 can be detected. It can be determined whether the second switching element is turned on or off.

The control unit 6 has a voltage command calculator 7, a first offset calculator 8a, a second offset calculator 8b, a first on/off signal generator 9a, and a second on/off signal generator 9b.

The voltage command calculator 7 calculates a first voltage command based on the control command for the AC rotary machine 1, and inputs the calculated first voltage command to the first offset calculator 8a. The first voltage command includes a voltage command Vu1 for the U1 phase, a voltage command Vv1 for the V1 phase, and a voltage command Vw1 for the W1 phase.

Also, the voltage command calculator 7 calculates a second voltage command based on the control command for the AC rotary machine 1, and inputs the calculated second voltage command to the second offset calculator 8b. The second voltage command includes a voltage command Vu2 for the U2 phase, a voltage command Vv2 for the V2 phase, and a voltage command Vw2 for the W2 phase.

The voltage command calculator 7 calculates the first voltage command and the second voltage command by current feedback control or V/F (Voltage/Frequency) control, for example.

In the case of current feedback control, the voltage command calculator 7 sets a current command for the AC rotating machine 1 as the control command, and determines the amplitude of the voltage command based on the set current command. More specifically, the voltage command calculator 7 calculates the first voltage command by proportional integral control so that the deviation between the current command for the AC rotating machine 1 and the current detection values Iu1s, Iv1s, Iw1s becomes zero. Calculate. Further, the voltage command calculator 7 calculates a second voltage command by proportional-integral control so that the deviation between the current command for the AC rotary machine 1 and the current detection values Iu2s, Iv2s, Iw2s becomes zero.

In the case of V/F control, the voltage command calculator 7 sets a speed command or frequency command for the AC rotating machine 1 as a control command, and determines the amplitude of the voltage command based on the set speed command or frequency command. do.

Since the V/F control is feedforward control, the voltage command calculator 7 calculates U1-phase current Iu1, V1-phase current Iv1, W1-phase current Iw1, U2-phase current Iu2, V2-phase current Iv2, and W2-phase current Iw2 information is not required. Therefore, in the case of V/F control, information on the U1 phase current Iu1, V1 phase current Iv1, W1 phase current Iw1, U2 phase current Iu2, V2 phase current Iv2, and W2 phase current Iw2 is input to the voltage command calculator 7. you don't have to.

The first offset calculator 8a calculates a first offset voltage Voffset1. The first offset calculator 8a obtains the first applied voltage by subtracting the first offset voltage Voffset1 from the first voltage command. The first offset calculator 8a outputs the obtained first applied voltage to the first on/off signal generator 9a.

The first applied voltage includes three applied voltages corresponding to three phases, that is, applied voltage Vu1′ corresponding to U1 phase, applied voltage Vv1′ corresponding to V1 phase, and applied voltage Vw1′ corresponding to W1 phase. include. That is, the first applied voltage is represented by the following formula (1).

Here, each phase in the first voltage command is called a first voltage maximum phase, a first voltage intermediate phase, and a first voltage minimum phase in descending order of voltage command. The voltage command for the first voltage maximum phase is called Vmax1, the voltage command for the first voltage intermediate phase is called Vmid1, and the voltage command for the first voltage minimum phase is called Vmin1.

Specifically, the first offset calculator 8a calculates the first offset voltage Voffset1 based on the following equation (2). At this time, the center value of the first applied voltage, that is, the neutral point potential of the first three-phase winding becomes -α.

A second offset calculator 8b calculates a second offset voltage Voffset2. The second offset calculator 8b obtains the second applied voltage by subtracting the second offset voltage Voffset2 from the second voltage command. The second offset calculator 8b outputs the obtained second applied voltage to the second on/off signal generator 9b.

The second applied voltage includes three applied voltages corresponding to three phases, that is, applied voltage Vu2′ corresponding to U2 phase, applied voltage Vv2′ corresponding to V2 phase, and applied voltage Vw2′ corresponding to W2 phase. include. That is, the second applied voltage is represented by the following formula (3).

Here, each phase in the second voltage command is called a second maximum voltage phase, a second intermediate voltage phase, and a second minimum voltage phase in descending order of voltage command. The voltage command for the second voltage maximum phase is called Vmax2, the voltage command for the second voltage intermediate phase is called Vmid2, and the voltage command for the second voltage minimum phase is called Vmin2.

Specifically, the second offset calculator 8b calculates the second offset voltage Voffset2 based on the following equation (4). At this time, the center value of the second applied voltage, that is, the neutral point potential of the second three-phase winding becomes -α.

The first on/off signal generator 9a generates a plurality of first on/off signals Qup1, Qun1, Qvp1, Qvn1, Qwp1 for the plurality of first switching elements Sup1 to Swn1 by comparing the first applied voltage and the first reference signal. , and Qwn1. The first reference signal is a carrier signal. The first on/off signal generator 9a outputs the calculated plurality of first on/off signals Qup1 to Qwn1 to the first power converter 4a.

The plurality of first on/off signals Qup1, Qvp1, Qwp1, Qun1, Qvn1, and Qwn1 turn on and off the plurality of first switching elements Sup1, Svp1, Swp1, Sun1, Svn1, and Swn1, respectively.

When the values of the plurality of first on/off signals Qup1 to Qwn1 are "1", the first on/off signal generator 9a outputs signals for turning on the corresponding plurality of first switching elements Sup1 to Swn1. Output to the converter 4a. When the values of the plurality of first on/off signals Qup1 to Qwn1 are "0", the first on/off signal generator 9a outputs signals for turning off the corresponding plurality of first switching elements Sup1 to Swn1. Output to the converter 4a.

The second on/off signal generator 9b generates a plurality of second on/off signals Qup2, Qun2, Qvp2, Qvn2, Qwp2 for the plurality of second switching elements Sup2 to Swn2 by comparing the second applied voltage and the second reference signal. , and Qwn2. The second reference signal is a carrier signal. The second on/off signal generator 9b outputs the calculated plurality of second on/off signals Qup2 to Qwn2 to the second power converter 4b.

The plurality of second on/off signals Qup2, Qvp2, Qwp2, Qun2, Qvn2, and Qwn2 turn on and off the plurality of second switching elements Sup2, Svp2, Swp2, Sun2, Svn2, and Swn2, respectively.

When the values of the plurality of second on/off signals Qup2-Qwn2 are "1", the second on-off signal generator 9b generates signals for turning on the corresponding plurality of second switching elements Sup2-Swn2. Output to the converter 4b. When the values of the plurality of second on/off signals Qup2-Qwn2 are "0", the second on-off signal generator 9b generates a signal for turning off the corresponding plurality of second switching elements Sup2-Swn2. Output to the converter 4b.

FIG. 2 is a diagram showing the relationship between the phases of the first three-phase windings U1, V1, W1 and the phases of the second three-phase windings U2, V2, W2 in FIG. The phase difference between the first three-phase windings U1, V1, W1 and the second three-phase windings U2, V2, W2 is zero.

FIG. 3 is a diagram showing the first voltage vector output by the first power converter 4a of FIG. The first power converter 4a outputs one of the eight first voltage vectors according to the ON/OFF states of the plurality of first switching elements Sup1 to Swn1. The eight first voltage vectors are V0(1), V1(1), V2(1), V3(1), V4(1), V5(1), V6(1), and V7(1) .

where V0(1) and V7(1) are zero voltage vectors. When the first power converter 4a outputs the zero voltage vector, the first bus current Iinv1, which is the bus current of the first power converter 4a, becomes zero. Also, V1(1), V2(1), V3(1), V4(1), V5(1), and V6(1) are effective voltage vectors. When the first power converter 4a is outputting the effective voltage vector, the first bus current Iinv1 is the current value of each phase or its inverted value.

FIG. 4 is a diagram showing the relationship between the plurality of first on/off signals Qup1-Qwn1 and the first voltage vector output by the first power converter 4a. As shown in FIG. 4, there are eight combinations of values of the plurality of first on/off signals Qup1 to Qwn1. For example, when Qup1 is "0", Qun1 is "1", Qvp1 is "0", Qvn1 is "1", Qwp1 is "0", and Qwn1 is "1", the first power converter 4a Output V0(1) as one voltage vector.

FIG. 5 is a diagram showing the second voltage vector output by the second power converter 4b of FIG. The second power converter 4b outputs any one of the eight second voltage vectors according to the ON/OFF states of the plurality of second switching elements Sup2 to Swn2. The eight second voltage vectors are V0(2), V1(2), V2(2), V3(2), V4(2), V5(2), V6(2), and V7(2) .

where V0(2) and V7(2) are zero voltage vectors. When the second power converter 4b is outputting the zero voltage vector, the second bus current Iinv2, which is the bus current of the second power converter 4b, becomes zero. Also, V1(2), V2(2), V3(2), V4(2), V5(2), and V6(2) are effective voltage vectors. When the second power converter 4b is outputting the effective voltage vector, the second bus line current Iinv2 becomes the current value of each phase or its inverted value.

Since the phase difference between the first three-phase winding and the second three-phase winding is zero, V1(1) and V1(2), V2(1) and V2(2), V3(1) and V3(2), V4(1) and V4(2), V5(1) and V5(2), V6(1) and V6(2) respectively match.

FIG. 6 is a diagram showing the relationship between the plurality of second on/off signals Qup2-Qwn2 and the second voltage vector output by the second power converter 4b. As shown in FIG. 6, there are eight combinations of values of the plurality of second on/off signals Qup2 to Qwn2. For example, when Qup2 is "0", Qun2 is "1", Qvp2 is "0", Qvn2 is "1", Qwp2 is "0", and Qwn2 is "1", the second power converter 4b Output V0(2) as a two-voltage vector.

FIG. 7 is a diagram showing waveforms of the first voltage commands Vu1, Vv1, Vw1. The first voltage commands Vu1, Vv1, Vw1 are represented by sine waves having phases different from each other by 120 degrees.

FIG. 8 is a diagram showing the waveform of the first offset voltage Voffset1. The first offset voltage Voffset1 calculated by Equation (2) is a signal with a period of 120 degrees. Therefore, the first offset voltage Voffset1 becomes a third harmonic signal with respect to the first voltage command whose one cycle is 360 degrees.

FIG. 9 is a diagram showing waveforms of the first applied voltages Vu1', Vv1', Vw1'. The first applied voltages Vu1', Vv1', Vw1' calculated by Equation (1) have waveforms as shown in FIG.

Although not shown, the second voltage commands Vu2, Vv2, Vw2 are represented by sine waves having phases different from each other by 120 degrees, like the first voltage commands Vu1, Vv1, Vw1. The second offset voltage Voffset2, like the first offset voltage Voffset1, is a third harmonic signal with respect to the second voltage command. The second applied voltages Vu2', Vv2', Vw2' have waveforms similar to those of the first applied voltages Vu1', Vv1', Vw1'.

FIG. 10 is a diagram for explaining the operation of the first on/off signal generator 9a of FIG. In FIG. 10, the voltage command Vu1 for the U1 phase, the voltage command Vv1 for the V1 phase, and the voltage command Vw1 for the W1 phase have a relationship of Vu1>Vv1>Vw1. C1 is the first carrier signal. The first carrier wave signal C1 is a triangular wave having a minimum value of -Vdc/2, a maximum value of Vdc/2, and a period of Tc.

The first on/off signal generator 9a compares the first carrier wave signal C1 as the first reference signal with the U1-phase applied voltage Vu1'. When the U1-phase applied voltage Vu1' is greater than or equal to the first carrier wave signal C1, the first on/off signal generator 9a outputs "1" and "0" as Qup1 and Qun1, respectively, to the first power converter 4a. When the U1-phase applied voltage Vu1' is smaller than the first carrier wave signal C1, the first on/off signal generator 9a outputs "0" and "1" as Qup1 and Qun1, respectively, to the first power converter 4a.

As a result, the first power converter 4a outputs V7(1) during t1 to t2 and t8 to t9, V2(1) during t2 to t3 and t7 to t8, t3 to t4 and t6 to t7 as the first voltage vector. V1(1) is output at , and V0(1) is output at t4 to t6.

FIG. 11 is a diagram for explaining the operation of the second on/off signal generator 9b of FIG. In FIG. 11, the voltage command Vu2 for the U2 phase, the voltage command Vv2 for the V2 phase, and the voltage command Vw2 for the W2 phase have a relationship of Vu2>Vv2>Vw2. C1 is the same first carrier signal as C1 in FIG.

The second on/off signal generator 9b compares the first carrier wave signal C1 as a second reference signal with the U2-phase applied voltage Vu2'. When the U2-phase applied voltage Vu2' is greater than or equal to the first carrier wave signal C1, the second on/off signal generator 9b outputs "1" and "0" as Qup2 and Qun2, respectively, to the second power converter 4b. When the U2-phase applied voltage Vu2' is smaller than the first carrier wave signal C1, the second on/off signal generator 9b outputs "0" and "1" as Qup2 and Qun2, respectively, to the second power converter 4b.

As a result, the second power converter 4b outputs V7(2) during t1 to t2 and t8 to t9, V2(2) during t2 to t3 and t7 to t8, t3 to t4 and t6 to t7 as the second voltage vector. V1(2) is output at , and V0(2) is output at t4 to t6.

In this way, by setting the first offset voltage Voffset1 and the second offset voltage Voffset2 as shown in equations (2) and (4), the central time of the active voltage vector section and the central time of the zero voltage vector section are set to can be aligned. The effective voltage vector section is the section in which the effective voltage vector is output. A zero-voltage vector section is a section in which a zero-voltage vector is output. Then, the first voltage vector and the second voltage vector in each section can be matched. Thereby, the phase current ripple can be reduced.

FIG. 12 is a diagram showing the relationship between the on/off timing of the first high potential side switching element and the output voltage vector. FIG. 13 is a diagram showing the relationship between the on/off timing of the second high potential side switching element and the output voltage vector. Here, the vertical axis is the voltage phase, and the voltage phase ranges from 0 degrees to 360 degrees. The horizontal axis corresponds to the period Tc of the first carrier wave signal C1.

As shown in FIGS. 12 and 13, for example, when the voltage phase is 40 degrees, the combination of the first voltage vector and the second voltage vector output simultaneously is V7(1), V7(2), V2(1 ) and V2(2), V1(1) and V1(2), and V0(1) and V0(2). Thus, the first voltage vector and the second voltage vector can be matched in each section of the voltage vector. This is because the neutral point potential of the first three-phase winding and the neutral point potential of the second three-phase winding are aligned by the above equations (2) and (4).

Next, a method of reducing the phase current ripple considering the combination of the first voltage vector and the second voltage vector will be described. Here, to simplify the explanation, the resistance component and the induced voltage component are assumed to be 0, but the case where the resistance component and the induced voltage component are not 0 can also be explained based on the same idea.

The d-axis voltage of the first power converter 4a is the first d-axis voltage Vd1, the q-axis voltage of the first power converter 4a is the first q-axis voltage Vq1, and the d-axis voltage of the second power converter 4b is the second d-axis voltage Vd2. , the q-axis voltage in the second power converter 4b is defined as a second q-axis voltage Vq2. At this time, the following formula (5) holds.

Assuming that the d-axis self-inductance is Ld, the d-axis mutual inductance is Md, the q-axis self-inductance is Lq, the q-axis mutual inductance is Mq, the electrical angle is θ, and the differential operator is p, differential values piu1 to piw2 of the six-phase current are obtained. can be represented by the following formula (6).

Let k be the coupling coefficient, and simplify as shown in Equation (7). Below, the differential value of the six-phase current is expressed as a ratio to the differential value pibase of the base current represented by Equation (8).

When the first power converter 4a outputs V1(1) as the first voltage vector and the second power converter 4b outputs V0(2) as the second voltage vector, the DC component of the differential value of the six-phase current piu1_dc to piw2_dc are given by the following equation (9). The efficiency of the AC rotating machine 1 is affected by phase current ripples of all six phases. Therefore, in order to improve the efficiency of the AC rotating machine 1, the square sum of the DC components of the differential values of the six-phase currents should be minimized. In this case, the sum of squares of the DC components of the differential values of the six-phase currents is represented by the following equation (10). The "sum of squares of the DC components of the differential values of the six-phase currents" is hereinafter abbreviated as "sum of squares of the differential DC".

When the coupling coefficient k is 0, no current flows through the U2 phase, the V2 phase, and the W2 phase, but the second power converter 4b outputs a zero voltage vector due to mutual inductance. Even if there is, when the first power converter 4a is outputting the active voltage vector, the current flowing through the second three-phase winding also changes. Therefore, current change occurs when an effective voltage vector is output from either the first power converter 4a or the second power converter 4b. Therefore, by overlapping the zero-voltage vector section by the first power converter 4a and the zero-voltage vector section by the second power converter 4b, the current change is suppressed and the phase current ripple is reduced.

Specifically, the overlapping of the zero voltage vector section by the first power converter 4a and the zero voltage vector section by the second power converter 4b is performed by the first applied voltage can be realized by aligning the center value of and the center value of the second applied voltage.

When the first power converter 4a outputs V1(1) as the first voltage vector and the second power converter 4b outputs V1(2) as the second voltage vector, the DC component of the differential value of the six-phase current is given by the following equation (11). In this case, the differential DC sum of squares is represented by the following equation (12).

When the first power converter 4a outputs V1(1) as the first voltage vector and the second power converter 4b outputs V2(2) as the second voltage vector, the DC component of the differential value of the six-phase current is given by the following equation (13). In this case, the differential DC sum of squares is represented by the following equation (14).

When the first power converter 4a outputs V1(1) as the first voltage vector and the second power converter 4b outputs V3(2) as the second voltage vector, the DC component of the differential value of the six-phase current is given by the following equation (15). In this case, the differential DC sum of squares is represented by the following equation (16).

When the first power converter 4a outputs V1(1) as the first voltage vector and the second power converter 4b outputs V4(2) as the second voltage vector, the DC component of the differential value of the six-phase current is given by the following equation (17). In this case, the differential DC sum of squares is represented by the following equation (18).

The differential DC sum of squares is determined by the phase difference between the first voltage vector and the second voltage vector. Therefore, the differential DC sum of squares when V1(1) and V5(2) are output simultaneously is equal to the differential DC sum of squares when V1(1) and V3(2) are output simultaneously. The differential DC sum of squares when V1(1) and V6(2) are output simultaneously is equal to the differential DC sum of squares when V1(1) and V2(2) are output simultaneously.

FIG. 14 is a diagram showing the relationship between the coupling coefficient k and the differential DC sum of squares. When V1(1) is output as the first voltage vector, in a region where the coupling coefficient k is greater than 0.27, V1(2) is output rather than V0(2) as the second voltage vector. By doing so, the change in the phase current can be made smaller. V0(2) is a zero voltage vector, and V1(2) is a voltage vector with zero phase difference from V1(1).

On the other hand, when V1(1) is output as the first voltage vector and V3(2) having a phase difference of 120 degrees from V1(1) is output as the second voltage vector, the change in phase current is Increase. Therefore, in order to reduce the phase current ripple, at least V3(2) having a phase difference of 120 degrees from V1(1) and V4(2) having a phase difference of 180 degrees from V1(1) should be V1( 1) It is necessary to avoid being output at the same time.

As described above, the first voltage vector V1(1) and the second voltage vector combined with the first voltage vector V1(1) have been described. The second voltage vector to be combined may be similarly considered.

Further, the second offset calculator 8b calculates the second offset voltage Voffset2 based on the following equation (19), and the second on/off signal generator 9b uses the second carrier signal C2 as the second reference signal. may The second carrier signal C2 is a signal that is 180 degrees out of phase with the first carrier signal C1. At this time, the center value of the second applied voltage, that is, the neutral point potential of the second three-phase winding is "α".

FIG. 15 is a diagram showing the relationship between the on/off timing of the first high potential side switching element and the output voltage vector. FIG. 16 is a diagram showing the relationship between the on/off timing of the second high potential side switching element and the output voltage vector. For example, when the voltage phase is 40 degrees, the combinations of the first voltage vector and the second voltage vector output at the same time are V7(1) and V0(2), V2(1) and V1(2), V2(1 ) and V2(2), V1(1) and V2(2), and V0(1) and V7(2).

In this example, the phase difference between the first voltage vector and the second voltage vector is 60 degrees, such as the combination of V2(1) and V1(2) and the combination of V1(1) and V2(2). Since there is a combination section, the phase current ripple is larger than in the cases of FIGS. 12 and 13 . However, since the active voltage vector section and the zero voltage vector section are aligned, the phase current ripple tends to be suppressed. A zero-voltage vector section is a section in which a zero-voltage vector is output.

Thus, even when the phase of the first reference signal and the phase of the second reference signal are shifted by 180 degrees, the central value of the second applied voltage is -1 times the central value of the first applied voltage. Thus, each offset voltage is subtracted from each voltage command. Thereby, the zero-voltage vector section of the first power converter 4a and the zero-voltage vector section of the second power converter 4b can be aligned. Also, this can reduce the phase current ripple.

That is, the first offset computing unit 8a calculates the central value of the three applied voltages corresponding to the three phases in the first applied voltage and the central value of the three applied voltages corresponding to the three phases in the second applied voltage K ₁ times is equal to the first offset voltage from the first voltage command. In addition, the second offset calculator 8b calculates the central value of the three applied voltages corresponding to the three phases in the first applied voltage and the central value of the three applied voltages corresponding to the three phases in the second applied voltage K ₁ times is equal to the second offset voltage from the second voltage command. If the phase of the first reference signal and the phase of the second reference signal are equal, K1 is " ₁ ", and if the phase of the first reference signal and the phase of the second reference signal differ by ₁₈₀ degrees, K1 is It is "-1". Thereby, the phase current ripple can be reduced.

FIG. 17 is a diagram for explaining the operation of the first on/off signal generator 9a of FIG. FIG. 17 shows a plurality of first on/off signals and first voltage vectors when α is set to "0" in Equation (2). Here, a period corresponding to two cycles of the carrier wave signal is shown.

When the fundamental wave component of the first applied voltage is removed, the phase currents of the first three-phase windings become equal at t1, t9, and t17. Also, in the section where the effective voltage vector is output, the differential value of the six-phase current is determined by the first voltage vector and the electrical angle, and the phase current changes according to the determined differential value. On the other hand, in the section in which the zero voltage vector is output, the phase current changes toward 0 so as to cancel the change in the phase current in the section in which the effective voltage vector is output.

If α is defined by the following equation (20), the applied voltage Vu1' of the U1 phase, which is the first voltage maximum phase, is Vdc/2, so the length of the section from t4 to t6 is 0. In this case, the peak value of the phase current ripple is twice the width of the current change from t2 to t4.

On the other hand, as shown in FIG. 17, when α is set to "0", the voltage command Vmax1 in the first voltage maximum phase and the voltage command Vmin1 in the first voltage minimum phase are arranged symmetrically about 0V. Therefore, the length of the section from t4 to t6 is equal to the sum of the length of the section from t1 to t2 and the length of the section from t8 to t9, that is, the length of the section from t8 to t10. Therefore, when the fundamental wave component of the first applied voltage is removed, the phase currents at t1, t5, t9, t13, and t17 are equal for each phase.

As a result, the peak value of the phase current ripple becomes equal to the width of the current change from t2 to t4. That is, by setting α to “0” and matching the center value of the three applied voltages corresponding to the three phases in the first applied voltage with the center of the amplitude of the first reference signal, the length of the section from t4 to t6 is The length is equal to the length of the section from t8 to t10. As a result, the zero voltage vectors are evenly arranged, and the effect of suppressing the phase current ripple can be improved. “Uniformly arranging the zero voltage vectors” means equalizing the length of the section for outputting the zero voltage vector V0(1) and the length of the section for outputting the zero voltage vector V7(1).

Further, since the operation of the second on/off signal generator 9b is the same as that of the first on/off signal generator 9a, detailed description thereof will be omitted. The center value of the three applied voltages corresponding to the three phases in the second applied voltage is matched with the center of the amplitude of the second reference signal.

Also, the modulation rate determines the length of the effective voltage vector section. Therefore, by setting the ratio of the modulation rate of the first voltage command to the modulation rate of the second voltage command to be 1:1, the effective voltage vector sections can be overlapped, and the phase current ripple can be further reduced. . Here, the modulation factor is defined as the ratio of the peak value of the line voltage to the DC voltage Vdc.

FIG. 18 is a configuration diagram showing an application example of the power converter of FIG. 1 to a generator motor. Since the configuration of the power converter is as described with reference to FIG. 1, the description thereof is omitted here. The generator motor is, for example, a vehicle generator motor. The generator motor has an AC rotating machine 1 and an internal combustion engine 801 . The generator motor is mounted on a vehicle (not shown).

As an auxiliary machine of the internal combustion engine 801 , the AC rotating machine 1 generates driving force for wheels provided on the vehicle via a drive system component (not shown), and also generates power using the rotation of the internal combustion engine 801 .

The closer the rotational speed of internal combustion engine 801 is to the idling rotational speed, the more frequently AC rotating machine 1 performs the power generation operation. In addition, when the engine is operated at a relatively low rotation speed near the idle rotation speed, the iron loss has a relatively large effect on the power generation efficiency.

According to the power converter of Embodiment 1, the phase current ripple in the power generation operation of the AC rotating machine 1 which is frequently performed near the idling speed of the internal combustion engine 801 is suppressed. As a result, iron loss is reduced and more efficient power generation is performed. Similarly, when the driving force is assisted by power running, the iron loss is reduced and efficient driving is performed, thereby further improving the fuel efficiency of the vehicle.

FIG. 19 is a configuration diagram showing an application example of the power conversion device of FIG. 1 to an electric motor for an electric power steering device. Since the configuration of the power converter is as described with reference to FIG. 1, the description thereof is omitted here. The AC rotary machine 1 is connected to an electric power steering device (not shown) of a vehicle.

The vehicle has a steering wheel 901 , front wheels 902 , a torque detector 903 , gears 904 and a control command generator 905 . The driver of the vehicle steers the front wheels 902 by turning the steering wheel 901 left and right. Torque detector 903 detects a steering torque Ts of the steering system and outputs the detected steering torque Ts to control command generator 905 .

Control command generator 905 calculates a control command for controlling AC rotating machine 1 based on steering torque Ts output from torque detector 903 . The calculated control command is input to the voltage command calculator 7 of the control section 6 . The control command generator 905 calculates a torque current command Iq_tgt as the control command using the following equation (21). where ka is a constant.

By using the power conversion device according to Embodiment 1 for the electric motor for the electric power steering device, the phase current ripple is reduced, and vibrations uncomfortable for the driver are suppressed from being transmitted to the driver via the steering wheel 901. be done. In addition, the noise transmitted into the passenger compartment is reduced.

Note that the constant ka may be set so as to change according to the steering torque Ts or the running speed of the vehicle. Here, the torque current command Iq_tgt is determined using equation (21), but the torque current command Iq_tgt may be determined based on known compensation control according to the steering situation. Here, for simplification, only the torque current command Iq_tgt for the q-axis current is determined. good.

As described above, the power converter according to Embodiment 1 includes the first power converter 4a, the second power converter 4b, and the controller 6. FIG. The first power converter 4a has a plurality of first switching elements Sup1 to Swn1, converts the DC voltage Vdc from the DC power supply 2 into a first AC voltage, and converts the first three-phase Applies to windings U1, V1, W1. The second power converter 4b has a plurality of second switching elements Sup2 to Swn2, converts the DC voltage Vdc into a second AC voltage, and converts the second three-phase windings U2, V2 of the AC rotary machine 1 to the second AC voltage. , W2.

The control unit 6 obtains first applied voltages Vu1′, Vv1′, Vw1′ obtained by subtracting a first offset voltage Voffset1 as a third harmonic signal from the first voltage commands Vu1, Vv1, Vw1, and a first reference voltage Vu1′, Vv1′, Vw1′. Compare with signal. Thereby, the control unit 6 calculates a plurality of first on/off signals Qup1 to Qwn1 for the plurality of first switching elements Sup1 to Swn1. The first voltage commands Vu1, Vv1, Vw1 are voltage commands for the first three-phase windings U1, V1, W1.

The control unit 6 generates second applied voltages Vu2′, Vv2′, Vw2′ obtained by subtracting a second offset voltage Voffset2 as a third-order harmonic signal from the second voltage commands Vu2, Vv2, Vw2, and a second reference voltage Vu2′, Vv2′, Vw2′. Compare with signal. Thereby, the control unit 6 calculates a plurality of second on/off signals Qup2 to Qwn2 for the plurality of second switching elements Sup2 to Swn2. The second voltage commands Vu2, Vv2, Vw2 are voltage commands for the second three-phase windings U2, V2, W2.

The control unit 6 adjusts the central value of the three applied voltages corresponding to the three phases in the _first applied voltage to K1 times the central value of the three applied voltages corresponding to the three phases in the second applied voltage. , the first offset voltage Voffset1 is subtracted from the first voltage command. Along with this, the control unit 6 subtracts the second offset voltage Voffset2 from the second voltage command.

The first reference signal and the second reference signal are carrier signals. When the phase of the first reference signal and the phase of the second reference signal are equal, K1 is ₁ , and when the phase of the first reference signal and the phase of the second reference signal differ by 180 degrees, K1 is _-1 . is.

According to this, since the central time of the effective voltage vector section in the first power converter 4a and the central time of the effective voltage vector section in the second power converter 4b are aligned, the effective voltage vector section becomes the shortest. As a result, the phase current ripple is reduced.

Also, the ratio between the modulation rate in the first voltage command and the modulation rate in the second voltage command is set to 1:1.

According to this, the effective voltage vector section by the first power converter 4a and the effective voltage vector section by the second power converter 4b can be overlapped, thereby more effectively reducing the phase current ripple. .

In addition, the control unit 6 causes the center value of the three applied voltages corresponding to the three phases in the first applied voltage to match the center of the amplitude of the first reference signal, and the three values corresponding to the three phases in the second applied voltage. The center value of the applied voltage is matched with the center of the amplitude of the second reference signal.

According to this, the zero voltage vector sections are evenly arranged. As a result, the phase current ripple is further reduced.

Further, the generator motor control device includes the power conversion device according to the first embodiment.

According to this, iron loss in the generator-motor is reduced, and efficient power generation is possible. Therefore, when applied to a vehicle generator-motor, the fuel consumption of the vehicle can be improved.

Also, the electric power steering system includes the power converter according to the first embodiment.

According to this, by reducing the phase current ripple of the power conversion device, the vibration transmitted to the driver via the steering wheel is suppressed, and the noise in the vehicle interior is reduced.

In the power converter according to Embodiment 1, the phase difference between the first three-phase winding and the second three-phase winding is set to zero, but the phase difference is not necessarily zero. does not have to be In other words, even when the phase difference between the first three-phase winding and the second three-phase winding is not zero, the middle time of the effective voltage vector section in the first power converter 4a and the second power converter By aligning with the mid-time of the effective voltage vector interval in 4b, the phase current ripple is reduced.

Further, the first current detector 5a is, for example, provided with a current detection resistor in series with each of the first low potential side switching elements Sun1, Svn1, and Swn1, and detects the current detection values Iu1s, Iv1s, and Iw1s. current detector.

Further, the first current detector 5a is provided with a current detection resistor between the first power converter 4a and the smoothing capacitor 3 to detect the input current to the first power converter 4a, and from the detected value , current detection values Iu1s, Iv1s, and Iw1s. In these cases, the on/off state of the plurality of first switching elements Sup1 to Swn1 may be determined in consideration of whether or not the current can be detected.

Further, the second current detector 5b is, for example, provided with a current detection resistor in series with each of the second low-potential side switching elements Sun2, Svn2, and Swn2 to detect the current detection values Iu2s, Iv2s, and Iw2s. current detector.

Further, the second current detector 5b is provided with a current detection resistor between the second power converter 4b and the smoothing capacitor 3 to detect the input current to the second power converter 4b, and from the detected value , current detection values Iu2s, Iv2s, and Iw2s. In these cases, the ON/OFF state of the plurality of second switching elements Sup2 to Swn2 may be determined in consideration of whether or not the current can be detected.

Embodiment 2.
20 is a configuration diagram showing a power converter according to Embodiment 2. FIG. The power converter of FIG. 20 is provided with a first current detector 5a1 instead of the first current detector 5a of FIG. 20 is provided with a second current detector 5b1 instead of the second current detector 5b of FIG.

Configurations other than the above are the same as those of the power conversion apparatus in FIG. Hereinafter, the description of the same configuration as that of the power converter of FIG. 1 will be omitted.

The first current detector 5a1 is connected in series with each of the three first low potential side switching elements Sun1, Svn1, and Swn1. The first current detector 5a1 has three shunt resistors. The three shunt resistors are a resistor for sensing the U1 phase current, a resistor for sensing the V1 phase current, and a resistor for sensing the W1 phase current.

More specifically, the shunt resistor for detecting the U1-phase current is connected between the U1-phase first low potential side switching element Sun1 and the negative terminal of the DC power supply 2 . A shunt resistor for detecting the V1-phase current is connected between the V1-phase first low potential side switching element Svn1 and the negative terminal of the DC power supply 2 . A shunt resistor for detecting the W1-phase current is connected between the W1-phase first low potential side switching element Swn1 and the negative terminal of the DC power supply 2 .

When the applied voltage as shown in FIG. 10 is input to the first on/off signal generator 9a, the first current detector 5a1 detects the current flowing through the first three-phase windings U1, V1, W1 at time t5. As detection values, Iu1s, Iv1s, and Iw1s are obtained. However, when any one of the first high-potential side switching elements Sup1, Svp1, and Swp1 is turned on, the first current detector 5a1 detects the current of the phase in which the first high-potential side switching element is turned on. I can't.

That is, the detected value Iu1s of the U1 phase is "0" between t1 to t4 and t6 to t9, the detected value Iv1s of the V1 phase is "0" between t1 to t3 and t7 to t9, and the W1 phase is "0" between t1 and t2 and between t8 and t9.

Therefore, the detected value Iu1s of the U1 phase changes from "0" toward the actually flowing current "Iu1" at time t4. Therefore, the first current detector 5a1 requires settling time for settling the detected current waveform. In order to secure the settling time, the range of applied voltage that allows current to be detected by the first current detector 5a1 is limited to -Vdc/2 to K ₂ ×Vdc. where K2 is a positive value less than _1/2 .

The second current detector 5b1 is connected in series with each of the three second low potential side switching elements Sun2, Svn2, and Swn2. The second current detector 5b1 has three shunt resistors. The three shunt resistors are a resistor for sensing the U2 phase current, a resistor for sensing the V2 phase current, and a resistor for sensing the W2 phase current.

More specifically, the shunt resistor for detecting the U2-phase current is connected between the U2-phase second low potential side switching element Sun2 and the negative terminal of the DC power supply 2 . A shunt resistor for detecting the V2-phase current is connected between the V2-phase second low potential side switching element Svn2 and the negative terminal of the DC power supply 2 . A shunt resistor for detecting the W2-phase current is connected between the W2-phase second low potential side switching element Swn2 and the negative terminal of the DC power supply 2 .

When the applied voltage as shown in FIG. 11 is input to the second on/off signal generator 9b, the second current detector 5b1 detects the current flowing through the second three-phase windings U2, V2, W2 at time t5. Iu2s, Iv2s and Iw2s are obtained as detection values. However, if any one of the second high-potential side switching elements Sup2, Svp2, and Swp2 is turned on, the second current detector 5b1 detects the current of the phase in which the second high-potential side switching element is turned on. I can't.

As in the case of the first current detector 5a1, a waveform settling time is required, so the range of applied voltage in which current can be detected in the second current detector 5b1 is limited to −Vdc/2 to K ₂ ×Vdc. be.

The first offset voltage Voffset1 is calculated according to the above equation (2), and when α is "0", the absolute value of the maximum applied voltage is equal to the absolute value of the minimum applied voltage. Therefore, if the maximum value of the applied voltage is K ₂ ×Vdc or less, it is possible to detect currents in three phases simultaneously at all electrical angles. Therefore, the maximum value of the modulation rate that enables current detection in three phases at the same time is _2K2 .

In the power converter according to the second embodiment, α is given by the following equation (22) so that the currents of the three phases can be detected simultaneously over a wider range of electrical angles. Here, the median value of the first applied voltage and the median value of the second applied voltage are both (K ₂ /2−1/4)×Vdc. Under this condition, when the modulation factor is (K ₂ +1/2) or less, the maximum applied voltage is K ₂ ×Vdc or less and the minimum applied voltage is -Vdc/2 or more at all electrical angles. . This makes it possible to detect currents in three phases at the same time.

When the phase of the first reference signal and the phase of the second reference signal differ by 180 degrees, the timing at which the first current detector 5a1 can detect currents in three phases simultaneously and the timing at which currents in three phases can be detected simultaneously in the second current detector 5b1 is detected at different timings.

Therefore, by equalizing the phase of the first reference signal and the phase of the second reference signal, it is possible to realize a state in which currents in three phases can be detected simultaneously over a wider range of electrical angles.

That is, the center value of the first applied voltage and the center value of the second applied voltage are set to (K ₂ /2−1/4)×Vdc, and the phase of the first reference signal and the phase of the second reference signal are made equal. Therefore, it is possible to suppress the fluctuation of the neutral point potential and reduce the phase current ripple. In addition, the upper limit of the modulation rate that allows detection of currents in three phases at the same time can be increased.

As described above, in the power converter according to the second embodiment, the plurality of first switching elements includes three first high potential side switching elements Sup1, Svp1, Swp1 and three first low potential side switching elements Sun1, Svn1 and Swn1 are included. Three first high potential side switching elements Sup1, Svp1, Swp1 and three first low potential side switching elements Sun1, Svn1, Swn1 correspond to each phase of the first three-phase winding.

The first power converter 4a further has a first current detector 5a1. The first current detector 5a1 detects the current flowing through each phase of the first three-phase winding. The first current detector 5a1 is connected in series with each of the three first low potential side switching elements Sun1, Svn1 and Swn1.

The plurality of second switching elements includes three second high potential side switching elements Sup2, Svp2, Swp2 and three second low potential side switching elements Sun2, Svn2, Swn2. Three second high potential side switching elements Sup2, Svp2, Swp2 and three second low potential side switching elements Sun2, Svn2, Swn2 correspond to each phase of the second three-phase winding.

The second power converter 4b further has a second current detector 5b1. The second current detector 5b1 detects the current flowing through each phase of the second three-phase winding. The second current detector 5b1 is connected in series with each of the three second low potential side switching elements Sun2, Svn2 and Swn2.

The control unit 6 sets the central values of the three applied voltages corresponding to the three phases in the first applied voltage and the central values of the three applied voltages corresponding to the three phases in the second applied voltage to (K ₂ /2-1/ 4) Set to xVdc. Also, the control unit 6 equalizes the phase of the first reference signal and the phase of the second reference signal. Here, the above control is performed in the range of the applied voltage in which the current can be detected by the first current detector 5a1 and the second current detector 5b1 is in the range from -Vdc/2 to K ₂ ×Vdc. It is time. Vdc is the value of DC voltage.

According to this, the first current detector is connected in series with the first low potential side switching element, and the second current detector is connected in series with the second low potential side switching element. Also, it is possible to achieve both current detection and phase current ripple reduction.

The first current detector 5a1 is provided between each of the first low potential side switching elements Sun1, Svn1, and Swn1 and each of the output points Pu1, Pv1, and Pw1 of the first power converter 4a. may Further, the second current detector 5b1 is provided between each of the second low potential side switching elements Sun2, Svn2, and Swn2 and each of the output points Pu2, Pv2, and Pw2 of the second power converter 4b. may

Embodiment 3.
21 is a configuration diagram showing a power converter according to Embodiment 3. FIG. The power converter of FIG. 21 is provided with a first current detector 5a2 instead of the first current detector 5a of FIG. 21 is provided with a second current detector 5b2 instead of the second current detector 5b of FIG.

Configurations other than the above are the same as those of the power conversion apparatus in FIG. Hereinafter, the description of the same configuration as that of the power converter of FIG. 1 will be omitted.

The first current detector 5a2 is connected in series with each of the three first high potential side switching elements Sup1, Svp1, and Swp1. The first current detector 5a2 has three shunt resistors. The three shunt resistors are a resistor for sensing the U1 phase current, a resistor for sensing the V1 phase current, and a resistor for sensing the W1 phase current.

More specifically, the shunt resistor for detecting the U1-phase current is connected between the U1-phase first high potential side switching element Sup1 and the positive terminal of the DC power supply 2 . A shunt resistor for detecting the V1-phase current is connected between the V1-phase first high potential side switching element Svp1 and the positive terminal of the DC power supply 2 . A shunt resistor for detecting the W1-phase current is connected between the W1-phase first high potential side switching element Swp1 and the positive terminal of the DC power supply 2 .

When the applied voltage as shown in FIG. 10 is input to the first on/off signal generator 9a, the first current detector 5a2 switches the first three-phase windings U1, V1, W1 to Iu1s, Iv1s, and Iw1s are obtained as detected values of the flowing current. However, if any one of the first low potential side switching elements Sun1, Svn1 and Swn1 is on, the first current detector 5a2 detects the current of the phase in which the first low potential side switching element is on. I can't. When the first on/off signal is generated by comparing the second carrier signal C2 whose phase is 180 degrees different from the first carrier signal C1, the first three-phase windings U1, V1, Iu1s, Iv1s, and Iw1s can be obtained as the detected values of the current flowing through W1.

That is, the detected value Iu1s of the U1 phase is "0" between t4 and t6, the detected value Iv1s of the V1 phase is "0" between t3 and t7, and the detected value Iw1s of the W1 phase is between t2 and t7. It becomes "0" during t8.

Therefore, the detected value Iw1s of the W1 phase changes from "0" toward the actually flowing current "Iw1" at time t8. Therefore, the first current detector 5a2 requires a settling time for the detected current waveform. In order to secure the settling time, the range of applied voltage that allows current to be detected by the first current detector 5a2 is limited to −K ₃ ×Vdc to Vdc/2. where K3 is a positive value less than _1/2 .

The second current detector 5b2 is connected in series with each of the three second high potential side switching elements Sup2, Svp2, and Swp2. The second current detector 5b2 has three shunt resistors. The three shunt resistors are a resistor for sensing the U2 phase current, a resistor for sensing the V2 phase current, and a resistor for sensing the W2 phase current.

More specifically, the shunt resistor for detecting the U2-phase current is connected between the U2-phase second high potential side switching element Sup2 and the positive terminal of the DC power supply 2 . A shunt resistor for detecting the V2-phase current is connected between the V2-phase second high potential side switching element Svp2 and the positive terminal of the DC power supply 2 . A shunt resistor for detecting the W2-phase current is connected between the W2-phase second high potential side switching element Swp2 and the positive terminal of the DC power supply 2 .

When the applied voltage as shown in FIG. 11 is input to the second on/off signal generator 9b, the second current detector 5b2 switches the second three-phase windings U2, V2, W2 to Iu2s, Iv2s, and Iw2s are obtained as detected values of the flowing current. However, if any of the second low potential side switching elements Sun2, Svn2, and Swn2 is on, the second current detector 5b2 detects the current of the phase in which the second low potential side switching element is on. I can't. When the second on/off signal is generated by comparing with the second carrier signal C2 whose phase is 180 degrees different from the first carrier signal C1, at time t5, the second three-phase windings U2, V2, Iu2s, Iv2s, and Iw2s can be obtained as the detected values of the current flowing through W2.

As in the case of the first current detector 5a2, a waveform settling time is required, so the range of applied voltage in which the current can be detected in the second current detector 5b2 is limited to −K ₃ ×Vdc to Vdc/2. be.

The first offset voltage Voffset1 is calculated according to the above equation (2), and when α is "0", the absolute value of the maximum applied voltage is equal to the absolute value of the minimum applied voltage. Therefore, if the maximum value of the applied voltage is -K ₃ ×Vdc or higher, it is possible to detect currents in three phases simultaneously at all electrical angles. Therefore, the maximum value of the modulation rate that allows current detection in _three phases at the same time is 3K3.

In the power converter according to Embodiment 3, α is given by the following equation (23) so that the currents of the three phases can be detected simultaneously over a wider range of electrical angles. At this time, the center value of the first applied voltage and the center value of the second applied voltage are both (1/4−K ₃ /2)×Vdc.

When the phase of the first reference signal and the phase of the second reference signal differ by 180 degrees, the timing at which the first current detector 5a2 can detect currents in three phases at the same time is detected at different timings.

Therefore, by equalizing the phase of the first reference signal and the phase of the second reference signal, it is possible to realize a state in which currents in three phases can be detected simultaneously over a wider range of electrical angles.

That is, the center value of the first applied voltage and the center value of the second applied voltage are set to (1/4−K ₃ /2)×Vdc, and the phase of the first reference signal and the phase of the second reference signal are made equal. Therefore, it is possible to suppress the fluctuation of the neutral point potential and reduce the phase current ripple. In addition, the upper limit of the modulation rate that allows detection of currents in three phases at the same time can be increased.

As described above, in the power converter according to the third embodiment, the plurality of first switching elements includes three first high potential side switching elements Sup1, Svp1, Swp1 and three first low potential side switching elements Sun1, Svn1 and Swn1 are included. Three first high potential side switching elements Sup1, Svp1, Swp1 and three first low potential side switching elements Sun1, Svn1, Swn1 correspond to each phase of the first three-phase winding.

The first power converter 4a further has a first current detector 5a2. The first current detector 5a2 detects the current flowing through each phase of the first three-phase winding. The first current detector 5a2 is connected in series with each of the three first high potential side switching elements Sup1, Svp1, Swp1.

The plurality of second switching elements includes three second high potential side switching elements Sup2, Svp2, Swp2 and three second low potential side switching elements Sun2, Svn2, Swn2. Three second high potential side switching elements Sup2, Svp2, Swp2 and three second low potential side switching elements Sun2, Svn2, Swn2 correspond to each phase of the second three-phase winding.

The second power converter 4b further has a second current detector 5b2. The second current detector 5b2 detects the current flowing through each phase of the second three-phase winding. The second current detector 5b2 is connected in series with each of the three second high potential side switching elements Sup2, Svp2, Swp2.

The control unit 6 sets the central value of the three applied voltages corresponding to the three phases in the first applied voltage and the central value of the three applied voltages corresponding to the three phases in the second applied voltage to (1/4−K ₃ / 2) Set to xVdc. Also, the control unit 6 equalizes the phase of the first reference signal and the phase of the second reference signal. Here, the above control is performed in the range of the applied voltage in which the current can be detected by the first current detector 5a2 and the second current detector 5b2, from -K ₃ ×Vdc to Vdc/2. It is time. Vdc is the value of DC voltage.

According to this, the first current detector is connected in series with the first high potential side switching element, and the second current detector is connected in series with the second high potential side switching element. Also, it is possible to achieve both current detection and phase current ripple reduction.

The first current detector 5a2 is provided between each of the first high potential side switching elements Sup1, Svp1, and Swp1 and each of the output points Pu1, Pv1, and Pw1 of the first power converter 4a. may Further, the second current detector 5b2 is provided between each of the second high potential side switching elements Sup2, Svp2, and Swp2 and each of the output points Pu2, Pv2, and Pw2 of the second power converter 4b. may

Embodiment 4.
22 is a configuration diagram showing a power converter according to Embodiment 4. FIG. The power converter of FIG. 22 is provided with a first current detector 5a3 instead of the first current detector 5a of FIG. 22 is provided with a second current detector 5b3 instead of the second current detector 5b of FIG.

Configurations other than the above are the same as those of the power conversion apparatus in FIG. Hereinafter, the description of the same configuration as that of the power converter of FIG. 1 will be omitted.

The first current detector 5a3 is connected in series with each of the three first low potential side switching elements Sun1, Svn1, and Swn1. The first current detector 5a3 has three shunt resistors. The three shunt resistors are a resistor for sensing the U1 phase current, a resistor for sensing the V1 phase current, and a resistor for sensing the W1 phase current.

More specifically, the shunt resistor for detecting the U1-phase current is connected between the U1-phase first low potential side switching element Sun1 and the negative terminal of the DC power supply 2 . A shunt resistor for detecting the V1-phase current is connected between the V1-phase first low potential side switching element Svn1 and the negative terminal of the DC power supply 2 . A shunt resistor for detecting the W1-phase current is connected between the W1-phase first low potential side switching element Swn1 and the negative terminal of the DC power supply 2 .

When the applied voltage as shown in FIG. 10 is input to the first on/off signal generator 9a, the first current detector 5a3 detects the current flowing through the first three-phase windings U1, V1, W1 at time t5. As detection values, Iu1s, Iv1s, and Iw1s are obtained. However, if any one of the first high-potential side switching elements Sup1, Svp1, and Swp1 is turned on, the first current detector 5a3 detects the current of the phase in which the first high-potential side switching element is turned on. I can't.

That is, the detected value Iu1s of the U1 phase is "0" between t1 to t4 and t6 to t9, the detected value Iv1s of the V1 phase is "0" between t1 to t3 and t7 to t9, and the W1 phase is "0" between t1 and t2 and between t8 and t9.

Therefore, the detected value Iu1s of the U1 phase changes from "0" toward the actually flowing current "Iu1" at time t4. Therefore, the first current detector 5a3 requires a settling time for the detected current waveform, and the period from t4 to t5 must be longer than the settling time. In other words, if K ₂ is a positive value of 1/2 or less, the range of applied voltage that allows current to be detected by the first current detector 5a3 is -Vdc/2 to K ₂ ×Vdc.

The second current detector 5b3 is connected in series with each of the three second high potential side switching elements Sup2, Svp2, and Swp2. The second current detector 5b3 has three shunt resistors. The three shunt resistors are a resistor for sensing the U2 phase current, a resistor for sensing the V2 phase current, and a resistor for sensing the W2 phase current.

More specifically, the shunt resistor for detecting the U2-phase current is connected between the U2-phase second high potential side switching element Sup2 and the positive terminal of the DC power supply 2 . A shunt resistor for detecting the V2-phase current is connected between the V2-phase second high potential side switching element Svp2 and the positive terminal of the DC power supply 2 . A shunt resistor for detecting the W2-phase current is connected between the W2-phase second high potential side switching element Swp2 and the positive terminal of the DC power supply 2 .

When the applied voltage as shown in FIG. 11 is input to the second on/off signal generator 9b, the second current detector 5b3 switches the second three-phase windings U2, V2, W2 to Iu2s, Iv2s, and Iw2s are obtained as detected values of the flowing current. However, if any one of the second low potential side switching elements Sun2, Svn2, and Swn2 is on, the second current detector 5b3 detects the current of the phase in which the second low potential side switching element is on. I can't.

As with the first current detector 5a3, the waveform needs a settling time, so the period from t8 to t9 must be longer than the settling time. In other words, if K ₃ is a positive value of 1/2 or less, the range of applied voltage that allows current to be detected by the second current detector 5b3 is −K ₃ ×Vdc to Vdc/2.

When the phase of the first reference signal and the phase of the second reference signal are made equal, the timing at which the first current detector 5a3 can simultaneously detect currents in three phases and the timing at which the second current detector 5b3 simultaneously detects currents in three phases It deviates from the timing at which detection is possible.

Therefore, by making the phase of the first reference signal and the phase of the second reference signal differ by 180 degrees, it is possible to realize a state in which currents can be detected simultaneously in three phases over a wider electrical angle range.

When the first offset voltage Voffset1 is given by the formula (2) and the second offset voltage Voffset2 is given by the formula (4), when α is "0", the maximum modulation rate at which currents in three phases can be detected simultaneously becomes 2×min(K ₂ , K ₃ ). where min(a,b) represents the minimum selection of a and b. For example, if a<b, then min(a,b)=a.

In the power converter according to the fourth embodiment, α is given by equation (24) so that the currents of the three phases can be detected simultaneously over a wider range of electrical angles. At this time, the central value of the first applied voltage is (min(K ₂ , K ₃ )/2-1/4)×Vdc, and the central value of the second applied voltage is (1/4-min(K ₂ , K ₃ )/2)×Vdc. Also, the maximum modulation rate at which currents in three phases can be detected simultaneously is (min(K ₂ , K ₃ )+1/2).

That is, in the fourth embodiment, the central value of the first applied voltage is (min(K ₂ , K ₃ )/2−1/4)×Vdc, and the central value of the second applied voltage is (1/4− min(K ₂ , K ₃ )/2)×Vdc, and the phase of the first reference signal and the phase of the second reference signal are shifted by 180 degrees. As a result, fluctuations in the neutral point potential can be suppressed and the phase current ripple can be reduced. In addition, the upper limit of the modulation rate that allows detection of currents in three phases at the same time can be increased.

As described above, in the power converter according to the fourth embodiment, the plurality of first switching elements includes three first high potential side switching elements Sup1, Svp1, Swp1 and three first low potential side switching elements Sun1, Svn1 and Swn1 are included. Three first high potential side switching elements Sup1, Svp1, Swp1 and three first low potential side switching elements Sun1, Svn1, Swn1 correspond to each phase of the first three-phase winding.

The first power converter 4a further has a first current detector 5a3. The first current detector 5a3 detects the current flowing through each phase of the first three-phase winding. The first current detector 5a3 is connected in series with each of the three first low potential side switching elements Sun1, Svn1 and Swn1.

The plurality of second switching elements includes three second high potential side switching elements Sup2, Svp2, Swp2 and three second low potential side switching elements Sun2, Svn2, Swn2. Three second high potential side switching elements Sup2, Svp2, Swp2 and three second low potential side switching elements Sun2, Svn2, Swn2 correspond to each phase of the second three-phase winding.

The second power converter 4b further has a second current detector 5b3. The second current detector 5b3 detects the current flowing through each phase of the second three-phase winding. The second current detector 5b3 is connected in series with each of the three second high potential side switching elements Sup2, Svp2, Swp2.

The control unit 6 sets the center value of the three applied voltages corresponding to the three phases at the first applied voltage to (min (K ₂ , K ₃ )/2−1/4)×Vdc, and at the second applied voltage The central value of the three applied voltages corresponding to the three phases is set to (1/4-min(K ₂ , K ₃ )/2)×Vdc. Further, the control unit 6 causes the phase of the first reference signal and the phase of the second reference signal to differ by 180 degrees. Here, the above control is performed when the range of the applied voltage in which the current can be detected by the first current detector 5a3 is in the range of -Vdc/2 to K ₂ ×Vdc, and the second current detector 5b3 This is when the applied voltage range in which the current can be detected by is in the range of -K ₃ ×Vdc to Vdc/2. Vdc is the value of DC voltage.

According to this, the first current detector is connected in series with the first high potential side switching element, and the second current detector is connected in series with the second low potential side switching element. Also, it is possible to achieve both current detection and phase current ripple reduction.

The first current detector 5a3 is provided between each of the first low potential side switching elements Sun1, Svn1, and Swn1 and each of the output points Pu1, Pv1, and Pw1 of the first power converter 4a. may Further, the second current detector 5b3 is provided between each of the second high potential side switching elements Sup2, Svp2, and Swp2 and each of the output points Pu2, Pv2, and Pw2 of the second power converter 4b. may

Also, the first current detector 5a3 is connected in series with the first high potential side switching elements Sup1, Svp1, and Swp1, and the second current detector 5b3 is connected to the second low potential side switching elements Sun2, Svn2, and Swn2. may be connected in series with

Embodiment 5.
23 is a configuration diagram showing a power converter according to Embodiment 5. FIG. An AC rotating machine 1a is connected to the power converter of FIG. 23 in place of the AC rotating machine 1 of FIG.

Configurations other than the above are the same as those of the power conversion apparatus in FIG. Hereinafter, the description of the same configuration as that of the power converter of FIG. 1 will be omitted.

In the AC rotating machine 1 of FIG. 1, as shown in FIGS. 3 and 5, the first three-phase windings U1, V1, W1 and the second three-phase windings U2, V2, W2 are connected to the first The AC rotating machine 1 is provided so that the phase difference between the three-phase windings U1, V1, W1 and the second three-phase windings U2, V2, W2 is zero. In the AC rotating machine 1a of FIG. 23, the first three-phase windings U1, V1, W1 and the second three-phase windings U2, V2, W2 are connected to the first three-phase windings U1, V1, W1 and the second three-phase windings U1, V1, W1. 2 are provided in the AC rotating machine 1a so that the phase difference with the three-phase windings U2, V2, W2 of No. 2 is 30 degrees.

24 is a diagram showing a first voltage vector and a second voltage vector output by the power converter of FIG. 23. FIG. As shown in FIG. 24, in the power converter according to Embodiment 5, the phase difference between the first three-phase windings U1, V1, W1 and the second three-phase windings U2, V2, W2 is 30 degrees. is.

For example, when controlling the AC rotating machine 1a by equalizing the phase of the first reference signal and the phase of the second reference signal, the first offset calculator 8a calculates the first offset voltage Voffset1 based on the equation (2). Calculate.
The first on/off signal generator 9a calculates a plurality of first on/off signals by comparing the first carrier wave signal C1 and the first applied voltage, and outputs the calculated plurality of first on/off signals to the first power converter. 4a.
Also, the second offset calculator 8b calculates the second offset voltage Voffset2 based on the equation (4).
The second on/off signal generator 9b calculates a plurality of second on/off signals by comparing the first carrier wave signal C1 and the second applied voltage, and outputs the calculated plurality of second on/off signals to the second power converter. 4b.

At this time, since the center value of the first applied voltage and the center value of the second applied voltage are both "-α", the zero voltage vector section can be maximized.
A zero voltage vector section is a section in which both the first power converter 4a and the second power converter 4b output a zero voltage vector.
And thereby, a phase current ripple can be reduced.

FIG. 25 is a diagram showing the relationship between the on/off timing of the first high potential side switching element and the output voltage vector when the central value of the first applied voltage is 0; FIG. 26 is a diagram showing the relationship between the on/off timing of the second high potential side switching element and the output voltage vector when the central value of the second applied voltage is 0. In FIG. In FIGS. 25 and 26, α is set to "0".

The voltage phase of the voltage vector output from the first power converter 4a and the voltage phase of the voltage vector output from the second power converter 4b are different by 30 degrees. Therefore, the combination of voltage vectors simultaneously output from the first power converter 4a and the second power converter 4b differs from the combination shown in FIGS.

FIG. 27 is a diagram showing the relationship between the coupling coefficient k and the differential DC sum of squares. The differential DC sum of squares is determined by the phase difference between the first voltage vector and the second voltage vector. Therefore, when V1(1) is output as the first voltage vector and V4(2) is output as the second voltage vector, the differential DC sum of squares V1(1) and V3(2) are output. is equal to the differential DC sum of squares when

The differential DC sum of squares when V1(1) and V5(2) are output is equal to the differential DC sum of squares when V1(1) and V2(2) are output. The differential DC sum of squares when V1(1) and V6(2) are output is equal to the differential DC sum of squares when V1(1) and V1(2) are output.

By the way, as described in the first embodiment, when the phase difference between the first three-phase winding and the second three-phase winding is 0 degree, for the first voltage vector V1(1), Only V1(2) was the combination of the second voltage vectors that minimized the sum of differential DC squares.
That is, the combination of the first voltage vector and the second voltage vector that minimizes the differential DC sum of squares is only the combination that makes the phase difference between the first voltage vector and the second voltage vector zero.

On the other hand, when the phase difference between the first three-phase winding and the second three-phase winding is 30 degrees as in the present embodiment, differential DC There are two combinations of second voltage vectors that minimize the sum of squares, V6(2) and V1(2). That is, the combination of the first voltage vector and the second voltage vector that minimizes the differential DC sum of squares is a combination that provides a phase difference of 30 degrees between the first voltage vector and the second voltage vector.

Therefore, by setting the phase difference between the first three-phase winding and the second three-phase winding to 30 degrees, the combination of the first voltage vector and the second voltage vector that minimizes the differential DC sum of squares can be determined. Increased choice.

When the coupling coefficient k is greater than 0.32, V1(2) or V6(2) is output as the second voltage vector rather than the zero voltage vector V0(2) as the second voltage vector. can reduce the current change. On the other hand, when V2(2) having a phase difference of 90 degrees from V1(1) or V3(2) having a phase difference of 150 degrees from V1(1) is output as the second voltage vector, current change becomes very large.

Therefore, in order to reduce the phase current ripple, the second voltage vector V1(2) or V6(2) having a phase difference of 30 degrees from the first voltage vector V1(1) and "V1(1)" are output at the same timing.

Although only the case where V1(1) is output as the first voltage vector has been described above, the same relationship holds when V2(1) to V6(1) are output as the first voltage vector.

FIG. 28 is a diagram showing a first example of a combination of the first voltage vector and the second voltage vector in the voltage phase region from 0 degrees to 60 degrees. For example, when the voltage phase is 40 degrees, the combination of the output first voltage vector and second voltage vector is as follows.
A: V7(1) and V7(2), B: V2(1) and V7(2), C: V2(1) and V2(2), D: V2(1) and V1(2), E: V1(1) and V1(2), F: V1(1) and V0(2), and G: V0(1) and V0(2)

In combination A and combination G, both the first voltage vector and the second voltage vector are zero voltage vectors. In combination B and combination F, one of the first voltage vector and the second voltage vector is a zero voltage vector. In combinations C, D, and E, the phase difference between the first voltage vector and the second voltage vector is 30 degrees. As a result, the change in phase current can be reduced, and the phase current ripple can be reduced.

However, in the region where the voltage phase is from 0 degrees to 30 degrees, there is a combination of V2(1) and V6(2), albeit for a short period. Since the phase difference between the first voltage vector and the second voltage vector in the combination of V2(1) and V6(2) is 90 degrees, the phase current ripple cannot be reduced in this section.

Further, when the AC rotating machine 1a is controlled by shifting the phase of the first reference signal and the phase of the second reference signal by 180 degrees, the first offset calculator 8a calculates the first offset voltage Voffset1 based on the equation (2). to calculate. The first on/off signal generator 9a calculates a plurality of first on/off signals by comparing the first carrier wave signal C1 and the first applied voltage, and outputs the calculated plurality of first on/off signals to the first power converter. 4a.

The second offset calculator 8b calculates the second offset voltage Voffset2 based on equation (19). The second on/off signal generator 9b calculates a plurality of second on/off signals by comparing the second carrier wave signal C2 and the second applied voltage, and outputs the calculated plurality of second on/off signals to the second power converter. 4b.

At this time, since the center value of the first applied voltage is "-α" and the center value of the second applied voltage is "α", the zero voltage vector section can be maximized. This reduces the phase current ripple.

FIG. 29 is a diagram showing a second example of a combination of the first voltage vector and the second voltage vector in the voltage phase region from 0 degrees to 60 degrees. For example, when the voltage phase is 20 degrees, the combination of the output first voltage vector and second voltage vector is as follows.
A: V7(1) and V0(2), B: V2(1) and V0(2), C: V2(1) and V1(2), D: V1(1) and V1(2), E: V1(1) and V6(2), F: V1(1) and V7(2), G: V0(1) and V7(2)

In combination A and combination G, both the first voltage vector and the second voltage vector are zero voltage vectors. In combination B and combination F, one of the first voltage vector and the second voltage vector is a zero voltage vector. In combinations C, D, and E, the phase difference between the first voltage vector and the second voltage vector is 30 degrees. As a result, the change in phase current can be reduced, and the phase current ripple can be reduced.

However, in the region where the voltage phase is from 30 degrees to 60 degrees, there is a combination of V1(1) and V2(2), albeit in a short section. Since the phase difference between the first voltage vector and the second voltage vector in the combination of V1(1) and V2(2) is 90 degrees, the phase current ripple cannot be reduced in this section.

Therefore, in the power converter according to Embodiment 5, in the entire voltage phase region, the phase difference between the first voltage vector and the second voltage vector is 30 degrees, or the phase difference between the first voltage vector and the second voltage vector is Control is performed such that at least one of them becomes a zero voltage vector.
For this purpose, the first on/off signal generator 9a and the second on/off signal generator 9b convert at least one of the first reference signal and the second reference signal into the first carrier signal C1 and the Switch to one of the second carrier signals C2.

FIG. 30 is a diagram showing a first example of switching of carrier signals according to voltage phases. The first offset calculator 8a calculates the first offset voltage Voffset1 based on equation (2) in the entire voltage phase region. The first on/off signal generator 9a calculates a plurality of first on/off signals by comparing the calculated first offset voltage Voffset1 and the first carrier wave signal C1.

In the region where the voltage phase is from 60n degrees to (60n+30) degrees, the second offset calculator 8b calculates the second offset voltage Voffset2 based on equation (19). where n is 0 or a positive integer. The second on/off signal generator 9b calculates a plurality of second on/off signals by comparing the calculated second offset voltage Voffset2 and the second carrier wave signal C2.

In the region where the voltage phase is from (60n+30) degrees to 60(n+1) degrees, the second offset calculator 8b calculates the second offset voltage Voffset2 based on equation (4). The second on/off signal generator 9b calculates a plurality of second on/off signals by comparing the calculated second offset voltage Voffset2 and the first carrier wave signal C1.

FIG. 31 is a diagram showing a third example of a combination of the first voltage vector and the second voltage vector in the voltage phase range of 0 degrees to 60 degrees. The description of V0,7(2) means that in the region where the voltage phase is from 0 degrees to 30 degrees, the voltage phase is V0(2) at the left end of FIG. 31, the left end of FIG. 31 is V7(2) and the center is V0(2). For example, when the voltage phase is 20 degrees, the combination of the output first voltage vector and second voltage vector is as follows.
A: V7(1) and V0(2), B: V2(1) and V0(2), C: V2(1) and V1(2), D: V1(1) and V1(2), E: V1(1) and V6(2), F: V1(1) and V7(2), G: V0(1) and V7(2)

In combination A and combination G, both the first voltage vector and the second voltage vector are zero voltage vectors. In combination B and combination F, one of the first voltage vector and the second voltage vector is a zero voltage vector. In combinations C, D, and E, the phase difference between the first voltage vector and the second voltage vector is 30 degrees. As a result, the change in phase current can be reduced, and the phase current ripple can be reduced.

Also, when the voltage phase is 40 degrees, the combination of the output first voltage vector and second voltage vector is as follows.
A: V7(1) and V7(2), B: V2(1) and V7(2), C: V2(1) and V2(2), D: V2(1) and V1(2), E: V1(1) and V1(2), F: V1(1) and V0(2), G: V0(1) and V0(2)

In combination A and combination G, both the first voltage vector and the second voltage vector are zero voltage vectors. In combination B and combination F, one of the first voltage vector and the second voltage vector is a zero voltage vector. In combinations C, D, and E, the phase difference between the first voltage vector and the second voltage vector is 30 degrees. As a result, the change in phase current can be reduced, and the phase current ripple can be reduced.

That is, since the phase difference between the first voltage vector and the second voltage vector is 30 degrees or at least one of the first voltage vector and the second voltage vector is a zero voltage vector, the phase current ripple is reduced.

In this example, even in the region where the voltage phase is from 60 degrees to 360 degrees, at least one of the first voltage vector and the second voltage vector is the zero voltage vector, or the first voltage vector and the first voltage vector The phase difference between the two voltage vectors can be 30 degrees.

In this example, the first carrier wave signal C1 is used as the first reference signal in the entire voltage phase range, and the first carrier wave signal C1 and the second carrier wave signal C2 are switched every 30 degrees as the second reference signal. was However, the first reference signal may also be switched according to the voltage phase.

FIG. 32 is a diagram showing a second example of switching of the carrier signal according to the voltage phase. Also, FIG. 33 is a diagram showing a third example of switching of the carrier signal according to the voltage phase.

In the region where the voltage phase is from 60n degrees to (60n+30) degrees, the carrier wave signal selected as the first reference signal and the carrier wave signal selected as the second reference signal are different. That is, the phase of the first reference signal and the phase of the second reference signal are 180 degrees different. where n is 0 or a positive integer. Therefore, the second on/off signal generator 9b calculates a plurality of second on/off signals by comparing the second applied voltage with the carrier wave signal whose phase is 180 degrees different from the phase of the first reference signal.

In the voltage phase region from (60n+30) degrees to 60(n+1) degrees, the carrier wave signal selected as the first reference signal and the carrier wave signal selected as the second reference signal are equal. That is, the phase of the first reference signal and the phase of the second reference signal are equal. Therefore, the second on/off signal generator 9b calculates a plurality of second on/off signals by comparing the carrier signal having the same phase as the first reference signal and the second applied voltage.

Needless to say, the first offset voltage Voffset1 and the second offset voltage Voffset2 are set according to the selected carrier wave signal.

An example of a control method for selecting a carrier wave signal is described below. In the region where the voltage phase is from 0 degrees to 30 degrees, the first power converter 4a outputs V1(1) and V2(1) as effective voltage vectors, and the second power converter 4b outputs the effective voltage vector , V6(2) and V1(2) are output. In this case, the first voltage maximum phase is the U1 phase, the second voltage maximum phase is the U2 phase, the first voltage minimum phase is the W1 phase, and the second voltage minimum phase is the V2 phase.

On the other hand, in the region where the voltage phase is from 30 degrees to 60 degrees, the first power converter 4a outputs V1(1) and V2(1) as effective voltage vectors, and the second power converter 4b outputs effective Output V1(2) and V2(2) as voltage vectors. In this case, the first voltage maximum phase is the U1 phase, the second voltage maximum phase is the U2 phase, the first voltage minimum phase is the W1 phase, and the second voltage minimum phase is the W2 phase.

Therefore, when the phase difference between the first voltage maximum phase and the second voltage maximum phase and the phase difference between the first voltage minimum phase and the second voltage minimum phase are 30 degrees, the phase of the first reference signal and the phase The carrier signal should be selected so that the phases of the two reference signals are equal. Further, when the phase difference between the first voltage maximum phase and the second voltage maximum phase is not 30 degrees, or when the phase difference between the first voltage minimum phase and the second voltage minimum phase is not 30 degrees, the first reference signal The carrier signal should be selected such that the phase of the second reference signal is 180 degrees different from the phase of the second reference signal.

With such a method, at least one of the first voltage vector and the second voltage vector can be set to a zero voltage vector, or the phase difference between the first voltage vector and the second voltage vector can be set to 30 degrees. . This can suppress changes in the phase current, and as a result, can reduce the phase current ripple.

As described above, in the power converter according to Embodiment 5, the phase of the first three-phase winding and the phase of the second three-phase winding are different by 30 degrees. The control unit 6 converts at least one of the first reference signal and the second reference signal to the first carrier signal and the second carrier signal according to the voltage phase so as to satisfy either of the following two conditions. switch to either
Condition 1: The phase difference between the first voltage vector and the second voltage vector is 30 degrees.
Condition 2: At least one of the first voltage vector and the second voltage vector is a zero voltage vector.

Here, the first voltage vector is the voltage vector output from the first power converter 4a based on the plurality of first on/off signals, and the second voltage vector is the second voltage vector based on the plurality of second on/off signals. It is a voltage vector output from the power converter 4b. Also, the voltage phase is the phase of the first voltage command and the second voltage command. Also, the phase is 180 degrees different from that of the first carrier signal and the second carrier signal.

According to this, phase current ripple is reduced by combining voltage vectors with small current changes.

Further, in the power converter according to Embodiment 5, the control unit 6 sets the phase difference between the first voltage maximum phase and the second voltage maximum phase and the phase difference between the first voltage minimum phase and the second voltage minimum phase to If it is 30 degrees, the phase of the first reference signal and the phase of the second reference signal are made equal.

Further, if either one of the phase difference between the first voltage maximum phase and the second voltage maximum phase and the phase difference between the first voltage minimum phase and the second voltage minimum phase is not 30 The phase of the reference signal and the phase of the second reference signal are made 180 degrees different.

Here, each phase in the first voltage command is defined as a first voltage maximum phase, a first voltage intermediate phase, and a first voltage minimum phase in descending order of voltage command, and each phase in the second voltage command is defined as a voltage command with a large voltage command. A second maximum voltage phase, a second intermediate voltage phase, and a second minimum voltage phase are used in order.

According to this, the carrier wave signal can be determined based on the magnitude order of the voltage commands.

In Embodiments 1 to 5, when the phase of the first reference signal and the phase of the second reference signal are the same, the same carrier signal may be used as the first reference signal and the second reference signal. included.

Also, as the first reference signal and the second reference signal, the first carrier wave signal C1 or the second carrier wave signal C2, which is a triangular wave, was used. may be used. Waves having shapes other than triangular waves include, for example, sawtooth waves.

Also, the functions of the power converters of the first to fifth embodiments are realized by processing circuits. FIG. 34 is a configuration diagram showing a first example of a processing circuit that implements the functions of the power converters of the first to fifth embodiments. The processing circuit 100 of the first example is dedicated hardware.

Further, the processing circuit 100 is, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof. Applicable.

Also, FIG. 35 is a configuration diagram showing a second example of a processing circuit that implements the functions of the power converters of the first to fifth embodiments. The second example processing circuit 200 comprises a processor 201 and a memory 202 .

In the processing circuit 200, the functions of the power converter are realized by software, firmware, or a combination of software and firmware. Software and firmware are written as programs and stored in memory 202 . The processor 201 implements functions by reading and executing programs stored in the memory 202 .

It can also be said that the program stored in the memory 202 causes the computer to execute the procedure or method of each part described above. Here, the memory 202 is a non-volatile memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable and Programmable Read Only Memory). volatile or volatile semiconductor memory. The memory 202 also includes magnetic disks, flexible disks, optical disks, compact disks, mini disks, DVDs, and the like.

It should be noted that the functions of the power conversion device described above may be partially realized by dedicated hardware and partially realized by software or firmware.

Thus, the processing circuitry may implement the functionality of the power conversion device described above through hardware, software, firmware, or a combination thereof.

1, 1a AC rotating machine 2 DC power supply 4a First power converter 4b Second power converter 5a, 5a1, 5a2, 5a3 First current detector 5b, 5b1, 5b2, 5b3 Second current detector , 6 control unit Sup1 to Swn1 first switching elements Sup1, Svp1, Swp1 first high potential side switching elements Sun1, Svn1, Swn1 first low potential side switching elements Sup2 to Swn2 second switching elements Sup2, Svp2 , Swp2 Second high-side switching element Sun2, Svn2, Swn2 Second low-side switching element U1, V1, W1 First three-phase winding U2, V2, W2 Second three-phase winding.

Claims (10)

A first power converter that has a plurality of first switching elements, converts a DC voltage from a DC power supply into a first AC voltage, and applies it to a first three-phase winding of an AC rotating machine;
a second power converter having a plurality of second switching elements, converting the DC voltage into a second AC voltage, and applying the DC voltage to a second three-phase winding of the AC rotating machine; and By comparing the first applied voltage obtained by subtracting the first offset voltage as the third harmonic signal from the first voltage command, which is the voltage command for the three-phase winding, with the first reference signal, the plurality of While calculating a plurality of first on-off signals for the first switching element of, subtracting a second offset voltage as a third harmonic signal from a second voltage command that is a voltage command for the second three-phase winding A control unit that calculates a plurality of second on/off signals for the plurality of second switching elements by comparing the obtained second applied voltage and a second reference signal,
The control unit
so that the central value of the three applied voltages corresponding to the three phases in the first applied voltage and the central value of the three applied voltages corresponding to the three phases in the second applied voltage are equal to K ₁ times Subtracting the first offset voltage from one voltage command and subtracting the second offset voltage from the second voltage command,
the first reference signal and the second reference signal are carrier signals;
When the phase of the first reference signal and the phase of the second reference signal are equal, the K1 is ₁ , and when the phase of the first reference signal and the phase of the second reference signal differ by 180 degrees, Said K ₁ is -1 Power converter. The power converter according to claim 1, wherein a ratio of the modulation rate in said first voltage command and the modulation rate in said second voltage command is set to 1:1. The phase of the first three-phase winding is different from the phase of the second three-phase winding by 30 degrees,
The control unit
A first voltage vector, which is a voltage vector output from the first power converter based on the plurality of first on/off signals, and a voltage vector output from the second power converter based on the plurality of second on/off signals The first reference signal and the At least one of the second reference signals is a first carrier wave signal and a second carrier wave signal whose phases are different by 180 degrees according to the voltage phase that is the phase of the first voltage command and the second voltage command. The power converter according to claim 1 or 2, wherein switching is performed between the two. Each phase in the first voltage command is set to a first voltage maximum phase, a first voltage intermediate phase, and a first voltage minimum phase in descending order of voltage command, and each phase in the second voltage command is set in descending order of voltage command. , second voltage maximum phase, second voltage intermediate phase, and second voltage minimum phase,
The control unit
When the phase difference between the first voltage maximum phase and the second voltage maximum phase and the phase difference between the first voltage minimum phase and the second voltage minimum phase are 30 degrees, the phase of the first reference signal and Equalize the phase of the second reference signal,
When either one of the phase difference between the first voltage maximum phase and the second voltage maximum phase and the phase difference between the first voltage minimum phase and the second voltage minimum phase is not 30 degrees, the first reference signal The power converter according to claim 3, wherein the phase of and the phase of the second reference signal are different from each other by 180 degrees. The control unit
The center value of the three applied voltages corresponding to the three phases in the first applied voltage is matched with the center of the amplitude of the first reference signal, and the center of the three applied voltages corresponding to the three phases in the second applied voltage The power converter according to any one of claims 1 to 4, wherein the value is matched with the center of the amplitude of the second reference signal. The plurality of first switching elements include three first high potential side switching elements corresponding to the phases of the first three-phase winding and three first high-potential side switching elements corresponding to the phases of the first three-phase winding. including three first low-side switching elements in which
The first power converter further includes a first current detector that detects a current flowing through each phase of the first three-phase winding,
The first current detector is connected in series with each of the three first low potential side switching elements,
The plurality of second switching elements include three second high potential side switching elements corresponding to each phase of the second three-phase winding and three second switching elements corresponding to each phase of the second three-phase winding. including three second low side switching elements in which
The second power converter further includes a second current detector that detects a current flowing through each phase of the second three-phase winding,
The second current detector is connected in series with each of the three second low potential side switching elements,
The control unit
Assuming that the value of the DC voltage is Vdc, the range of the applied voltage in which the current can be detected by the first current detector and the second current detector is a range from -Vdc/2 to K ₂ ×Vdc , When K2 is a positive value less than 1/2 _,
The central value of the three applied voltages corresponding to the three phases in the first applied voltage and the central value of the three applied voltages corresponding to the three phases in the second applied voltage are respectively (K / _2-1 /4) × set to Vdc,
The power converter according to any one of claims 1 to 4, wherein the phase of the first reference signal and the phase of the second reference signal are made equal. The plurality of first switching elements include three first high potential side switching elements corresponding to the phases of the first three-phase winding and three first high-potential side switching elements corresponding to the phases of the first three-phase winding. including three first low-side switching elements in which
The first power converter further includes a first current detector that detects a current flowing through each phase of the first three-phase winding,
The first current detector is connected in series with each of the three first high potential side switching elements,
The plurality of second switching elements include three second high potential side switching elements corresponding to each phase of the second three-phase winding and three second switching elements corresponding to each phase of the second three-phase winding. including three second low side switching elements in which
The second power converter further includes a second current detector that detects a current flowing through each phase of the second three-phase winding,
The second current detector is connected in series with each of the three second high potential side switching elements,
The control unit
Assuming that the value of the DC voltage is Vdc, the range of the applied voltage in which the current can be detected by the first current detector and the second current detector is a range from -K ₃ ×Vdc to Vdc/2 , When K3 is a positive value less than 1/2 _,
The median value of the three applied voltages corresponding to the three phases in the first applied voltage and the median value of the three applied voltages corresponding to the three phases in the second applied voltage are respectively (1/4−K ₃ /2)× set to Vdc,
The power converter according to any one of claims 1 to 4, wherein the phase of the first reference signal and the phase of the second reference signal are made equal. The plurality of first switching elements include three first high potential side switching elements corresponding to the phases of the first three-phase winding and three first high-potential side switching elements corresponding to the phases of the first three-phase winding. including three first low-side switching elements in which
The first power converter further includes a first current detector that detects a current flowing through each phase of the first three-phase winding,
The first current detector is connected in series with each of the three first low potential side switching elements,
The plurality of second switching elements include three second high potential side switching elements corresponding to each phase of the second three-phase winding and three second switching elements corresponding to each phase of the second three-phase winding. including three second low side switching elements in which
The second power converter further includes a second current detector that detects a current flowing through each phase of the second three-phase winding,
The second current detector is connected in series with each of the three second high potential side switching elements,
The control unit
Assuming that the value of the DC voltage is Vdc, the applied voltage range in which the current can be detected by the first current detector is from −Vdc/2 to K ₂ ×Vdc, and the second current detector When the applied voltage range in which the current can be detected is from −K ₃ ×Vdc to Vdc/2, and both K ₂ and K ₃ are positive values less than 1/2 ,
setting the center value of the three applied voltages corresponding to the three phases in the first applied voltage to (min (K ₂ , K ₃ )/2−1/4)×Vdc;
setting the center value of the three applied voltages corresponding to the three phases in the second applied voltage to (1/4-min(K ₂ , K ₃ )/2)×Vdc;
The power converter according to any one of claims 1 to 4, wherein the phase of the first reference signal and the phase of the second reference signal are different by 180 degrees. A generator-motor control device comprising the power conversion device according to any one of claims 1 to 8. An electric power steering device comprising the power conversion device according to any one of claims 1 to 8.

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