JPH09215341A - High-frequency leakage current reducing device in inverter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen high-frequency leakage current by detecting high-frequency leakage current appearing on a three-phase power line and amplifying the detected high-frequency leakage current and then causing the amplified high-frequency leakage current of an opposite phase to flow electromagnetically in the three-phase power line. SOLUTION: Rotary torque is generated by a three-phase motor according to the three-phase AC current generated by an inverter device 3 and a vehicle is driven by the rotary torque. At that time, zero-phase leakage current of the three-phase AC current at a common mode supplied to the three-phase motor 13 from the inverter device 3 via a three-phase power line 5 is detected by a current detecting coil 7. The detected leakage current is supplied to a high-frequency amplifier 9 and is power-amplified. The amplified current of an opposite phase is caused to flow electromagnetically in the three-phase power line 5 through a matching coil 11. By this method, high-frequency leakage current can be lessened and thereby the troubles due to electromagnetic noise can be eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency leakage current reducing device in an inverter device capable of reducing the leakage current generated in the inverter device.

[0002]

2. Description of the Related Art Generally, in an electric vehicle, a direct current supplied from a main battery is turned on by a switching element according to a PWM signal separately input by an inverter device.
The N / OFF control is performed to generate a three-phase alternating current, and the alternating current is applied to the three-phase motor to drive the vehicle.

When this switching device is used, when a switching element in the switching device switches using a three-phase motor or a power supply line as a load, a zero-phase leakage current having a pulsed positive polarity or a negative damped oscillation waveform is generated. Since it is generated, the radio noise trouble is caused by the high frequency component of the generated leakage current.

Therefore, in order to reduce the leakage current generated on the three-phase power supply line wired between the inverter device and the three-phase motor, conventionally, the IEEJ Transactions on D (115 Vol. 1)
No. pp. 77-83 1995, National Conference of the Institute of Electrical Engineers of Japan, No. 756), there is known a method of reducing leakage current using a common mode choke or a common mode transformer. The method using the common mode choke is to insert a common mode choke on the three-phase power line that is wired between the inverter device and the three-phase motor, and increase the impedance of the three-phase power line to the common mode to achieve zero. This is to reduce the peak value of the phase current. The method using the common mode transformer is to add a secondary winding to the common mode choke to construct a common mode transformer, and short-circuit this secondary winding with an appropriate resistor R so that the resistor R can eliminate zero. The energy of the phase component is consumed and the effective value of the leakage current is reduced.

[0005]

However, in the conventional method for reducing the leakage current, a larger inductance is required to increase the leakage current reducing effect. In particular, in an inverter device for supplying a large amount of power, a common mode choke or a common mode transformer has an extremely large shape and weight, which causes a problem of high cost. Further, it is impossible to reduce the leakage current to zero when the conventional method for reducing the leakage current is used. The present invention has been made in view of the above, and an object thereof is to provide an inverter device capable of reducing high-frequency leakage current generated on a three-phase power supply line wired between an inverter device and a three-phase motor. An object is to provide a high frequency leakage current reduction device.

[0006]

According to the first aspect of the present invention,
In order to solve the above problems, a high-frequency leakage current reducing device in an inverter device for reducing high-frequency leakage current generated on a three-phase power supply line that is wired between an inverter device and a three-phase motor, Current detecting means for detecting a high frequency leakage current generated on the phase power supply line, high frequency amplifying means for amplifying the detected high frequency leakage current, and the amplified high frequency leakage current electromagnetically to the three-phase power supply line in opposite phase. And a reverse phase injection means for injecting.

In order to solve the above-mentioned problems, the present invention provides an inverter device for reducing high-frequency leakage current generated on a three-phase power supply line wired between an inverter device and a three-phase motor. A high frequency leakage current reducing device, wherein current waveform generating means for generating a pseudo high frequency leakage current waveform in response to a drive pulse for driving a switching element inside the inverter device, and the generated pseudo high frequency leakage current High-frequency amplification means for amplifying
And a reverse phase injection means for electromagnetically injecting the amplified pseudo high frequency leakage current into the three-phase power supply line in a reverse phase.

In order to solve the above problems, the high frequency amplifying means has control means for controlling the amplification factor so that the high frequency leak current generated on the three-phase power supply line is minimized. That is the summary.

According to a fourth aspect of the present invention, in order to solve the above-mentioned problems, the anti-phase injecting means has a positive or negative damped vibration in accordance with a drive pulse for driving a switching element inside the inverter device. The gist is to have a waveform generating means for generating a waveform.

[0010]

As described above, according to the present invention as set forth in claim 1, the high frequency leakage current generated on the three-phase power supply line wired between the inverter device and the three-phase motor is detected. Amplifies the detected high frequency leakage current. Next, the amplified high frequency leakage current is electromagnetically injected into the three-phase power line in the opposite phase to cancel the high-frequency leakage current generated on the three-phase power line. It is possible to reduce high frequency leakage current.

According to the second aspect of the present invention, the waveform of the high frequency leakage current is artificially generated according to the drive pulse for driving the switching element inside the inverter device, and the generated pseudo high frequency leakage is generated. Amplify the current. Next, by electromagnetically injecting the amplified pseudo high-frequency leakage current into the three-phase power line in the opposite phase, the high-frequency leakage current generated on the three-phase power line is canceled out. The high frequency leakage current generated can be reduced.

According to the third aspect of the present invention, the high-frequency leakage current generated on the three-phase power supply line is controlled by controlling the amplification factor so that the high-frequency leakage current generated on the three-phase power supply line is minimized. Can be canceled to minimize
It is possible to reduce the high frequency leakage current generated on the three-phase power supply line to the minimum.

According to the present invention as defined in claim 4, after the positive or negative damping vibration waveform is generated in response to the drive pulse for driving the switching element in the inverter device, the positive or negative By electromagnetically injecting a negative damping vibration waveform into the three-phase power supply line, the high-frequency leakage current generated on the three-phase power supply line is canceled, so the high-frequency leakage current generated on the three-phase power supply line is reduced. can do.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIGS. 1A and 1B are diagrams showing a system configuration of a high frequency leakage current reducing apparatus 1 according to a first embodiment of the present invention. As shown in FIGS. 1 (a) and 1 (b), the high frequency leakage current reduction device 1 controls ON / OFF of a switching element of a direct current (DC input) supplied from a main battery according to a PWM signal. Inverter device 3 for generating a phase alternating current, and a current detection coil 7 for detecting a high frequency leakage current generated on the three-phase power supply line 5.
A high-frequency amplifier 9 for power-amplifying the detected high-frequency leakage current, a matching coil 11 for electromagnetically injecting the amplified high-frequency leakage current into the three-phase power supply line 5 in an opposite phase, and a matching coil 11 generated by the inverter device 3. It is composed of a three-phase motor 13 that drives the vehicle by generating a rotational torque according to the three-phase alternating current, and a controller 15 that controls the amplification factor of the high-frequency amplifier 9.

Next, the operation of the high frequency leakage current reducing apparatus 1 will be described with reference to FIG. First, the direct current (DC input) supplied from the main battery is the inverter device 3
At, the switching element is ON / OFF controlled according to the separately input PWM signal to generate a three-phase AC current. Next, the three-phase motor 13 generates a rotation torque according to the three-phase AC current generated by the inverter device 3 to drive the vehicle. Here, the common mode zero-phase leakage current of the three-phase AC current supplied from the inverter device 3 to the three-phase motor 13 via the three-phase power supply line 5 is detected by the current detection coil 7. The leakage current detected by the current detection coil 7 is supplied to the high frequency amplifier 9 for power amplification. The common mode power is amplified and then electromagnetically injected into the three-phase power supply line 5 via the matching coil 11 in antiphase. In this way, when the supplied anti-phase currents are equal to the zero-phase leakage current, they cancel each other out, so that the leakage current can be made zero.

The amplification factor of the high-frequency amplifier 9 is adjusted and fixed in advance so that the currents become equal. However, the coupling factor of each coil and the amplification factor of the high-frequency amplifier 9 may be changed by external factors such as temperature change. When changing, the controller 15 may be provided as needed to control the amplification factor of the high-frequency amplifier 9 to maintain a desired condition. Further, the bandwidth of the high-frequency amplifier 9 covers the frequency band of AM radio broadcasting, for example, as a frequency band in which at least leakage current is desired to be reduced from the switching fundamental wave of the inverter device 3. Further, the current detection coil 7 may be of a size that does not cause saturation or the like due to leakage current,
The matching coil 11 may be of a size that does not interfere with the output power of the high-frequency amplifier 9, so that a coil that is considerably smaller and lighter than the conventional common mode choke may be used.

As described above, when the antiphase current supplied to the zero-phase leakage current is made equal, the zero-phase leakage current can be experimentally reduced by 10 dB or more. As shown in FIG. 1B, a controller 15 is provided, and the leakage current value detected by the current detection coil 7 is input to the controller 15 to control the amplification factor of the high frequency amplifier so that this value becomes zero. By doing so, the zero-phase leakage current that constantly flows through the three-phase power supply line 5 of the inverter device 3 becomes zero regardless of changes in external factors such as the operating states of the three-phase motor 13 and the inverter device 3 and the temperature difference. Therefore, the more stable high frequency leakage current reducing device 1 can be configured.
In addition, the delay time from the detection of the leakage current until the amplification factor of the high frequency amplifier 9 is controlled, the control error due to the delay between the input and output of the high frequency amplifier 9, and the S / N deterioration in the state where the leakage current is close to zero. Even if the control error due to the above is taken into consideration, the effect of reducing the leakage current of 10 dB or more has been confirmed experimentally.

(Second Embodiment) FIG. 2 is a diagram showing a system configuration of a high frequency leakage current reducing apparatus 1 according to a second embodiment of the present invention. As shown in FIG. 2, the features of the high frequency leakage current reduction device 1 are that, in addition to those shown in FIG.
Logic circuits 21a to 21c for inputting an upper side (U) signal, a lower side (L) signal and a polarity signal (P) for OFF control and selecting a drive pulse, and the logic circuits 21a to 21a.
21 c, which delays the drive pulse output from 21 c by an arbitrary set time and outputs the drive pulse, and a waveform of a pseudo high-frequency leakage current in response to the drive pulse delayed via the delay circuits 23 a to 23 c. Waveform synthesizer 25a to 25c for generating a waveform, and waveform synthesis of synthesizing a pseudo three-phase high frequency leakage current waveform by inputting the waveform of the high frequency leakage current of each phase pseudo generated by the waveform generators 25a to 25c. 27, a current detection transformer 29 for detecting a high frequency leakage current generated on the three-phase power supply line 5, and a pseudo high frequency leakage current amplified by the high frequency amplifier 9 to have opposite phases, and the three-phase power supply line 5 is electromagnetically coupled. And a matching transformer 31 for selectively injecting.

Next, FIG. 3 is a diagram showing a logic circuit 21a for one phase, a delay circuit 23a, a waveform generator 25a and a waveform synthesizer 27 which constitute the high frequency leakage current reducing apparatus 1. As shown in FIG. 3, in the logic circuit 21a, an upper side (U) signal, a lower side (L) signal, and a polarity signal (P) for controlling ON / OFF of a switching element inside the inverter device 3 are input, AN according to the logic of the polarity signal (P)
Either the upper side (U) signal or the lower side (L) signal input to the D gates 41 and 45 is selected, and the OR gate 47 outputs a drive pulse for one phase. Next, in the delay circuit 23a, the drive pulse for one phase output from the logic circuit 21a is delayed and output corresponding to the time constant composed of the semi-fixed resistor VR1 and the capacitor C1. Next, the logic of the drive pulse delayed by the inverter 49 is inverted.

Here, the zero-phase leakage current generated by the inverter device 3 is a pulse-like one that is generated when the switching element inside the inverter device 3 switches by using the three-phase motor 13 or the three-phase power supply line 5 as a load. In general, as shown in FIG. 4A, since it is a positive (a) or negative (b) damping oscillation waveform, each constant of the LCR circuit is optimized and set in the waveform generator 25a. by doing,
A leak current waveform for one phase can be artificially generated.
Next, in the operational amplifier OP1, the pseudo leak current waveform is input and impedance conversion is performed, and the waveform for each phase is synthesized at the connection point of the resistors R2, R4, and R5. Next, in the operational amplifier OP2, this composite waveform is input, impedance conversion is performed, and the result is output to the high-frequency amplifier 9, so that as a power supply used for driving the three-phase motor, as shown in FIG. 4B. It is possible to generate a pseudo leak current waveform such as an example of the waveform of the zero-phase leak current observed in the AC line (c) and the DC power supply line (d) input to the inverter device 3.

Further, the matching transformer 31 includes the three-phase power line 5
And a total of four output lines of the high frequency amplifier 9 are bundled and wound (penetrated) once in the ferrite core. The larger the permeability of the ferrite material and the larger the number of turns, the higher the degree of coupling and the smaller the loss. In the present embodiment, μ = 10000
A ferrite core of a certain degree was used. Since the three-phase power supply line 5 is generally thick, it is difficult to wind it a large number of times. Therefore, it is possible to deal with this coupling loss by increasing the output power of the high frequency amplifier 9 while winding it once. .

Next, the operation of the high frequency leakage current reducing apparatus 1 will be described with reference to FIG. First, in the inverter device 3, a direct current (DC input) supplied from the main battery controls ON / OFF of a switching element according to a separately input PWM signal to generate a three-phase alternating current.
Next, the three-phase motor 13 generates a rotation torque according to the three-phase AC current generated by the inverter device 3 to drive the vehicle. Here, the waveform generator 25 artificially generates a waveform of the high-frequency leakage current in response to the drive pulse for driving the switching element inside the inverter device 3. Next, the generated pseudo high frequency leakage current is amplified by the high frequency amplifier 9. Next, the amplified pseudo high frequency leakage current is electromagnetically injected into the three-phase power supply line 5 in the opposite phase by the matching transformer 31. In this way, since the high frequency leakage current generated on the three-phase power supply line 5 is canceled out, the high frequency leakage current generated on the three-phase power supply line can be reduced.

The output of the waveform generator 25 is amplified by the wide-band high-frequency amplifier 9 and then electromagnetically injected into the three-phase power supply line 5 through the matching transformer 31 in the opposite phase. Not limited to such a case, as a method of creating an opposite phase when electromagnetically injected into the three-phase power supply line 5, when the winding of the matching transformer 31 is inverted, the waveform generator 25 is used.
When inverting the trigger pulse of a in advance (FIG. 3 shows this example; the waveform is shaped by the inverter device 3), a high-frequency current generated in three phases is also generated by using an inverting amplifier for the high-frequency amplifier 9. It is possible to electromagnetically inject the power line 5 in the opposite phase.

In order to make the zero-phase leakage current and the generated high frequency current have the same amplitude amount, if the amplification factor of the high frequency amplifier 9 is set to have the same amplitude in advance, three separate current monitoring transformers are required. It may be provided in the phase power supply line 5, and the case where the controller 15 controls the amplification factor of the high frequency amplifier 9 so that the zero-phase current of the three-phase power supply line 5 is minimized may be used. Thus, the leakage current reduction effect of 20 dB or more has been confirmed experimentally. The present embodiment can be applied to an inverter device that drives a 10 kw class three-phase AC induction motor as the three-phase motor 13. The inverter device obtains the driving PWM pulse by comparing the triangular waves.

(Third Embodiment) FIG. 5 is a diagram showing a system configuration of a high frequency leakage current reducing apparatus 1 according to a third embodiment of the present invention. As shown in FIG. 5, in addition to the features shown in FIGS. 2 and 3, the high frequency leakage current reduction device 1 is characterized by an inverter 49 for inverting a drive pulse for one phase from the delay circuit 23a and an inverter 49. Drive circuit 51 that drives the switching element bridges Tr1 and Tr2 in accordance with the drive pulse of the above, and drive that internally inverts the drive pulse from the inverter 49 and then drives the switching element bridges Tr3 and Tr4 in accordance with the inverted drive pulse. Circuit 53 and a switching element bridge Tr for switching and connecting one end of the LCR circuit to the power supply Vcc or GND
1, Tr2 and switching element bridges Tr3, Tr4,
An LCR circuit formed of an inductance L2, a capacitor C6, and a resistor R6 having a frequency approximating a high-frequency leakage current signal to form a positive or negative damping vibration waveform, and a damping vibration waveform generated by the LCR circuit in three phases The matching transformer 57 electromagnetically injected into the power supply line 5 and the collector voltage Vcc of the switching element bridges Tr1 and Tr3 are variably set, and Vcc is set so that the zero-phase leakage current detected by the current detection transformer 29 is minimized. It is composed of a control circuit 55 for variably controlling. Since L2 is wound around the ferrite core penetrating the three-phase power line 5, the damped vibration waveform generated in the LCR circuit is electromagnetically injected into the three-phase power line 5 as it is.

Next, the operation of the high frequency leakage current reducing device 1 will be described with reference to FIG. First, when the drive pulse from the inverter 49 is a positive drive pulse that changes from Low to High, the drive circuit 51 turns on the switching element bridge Tr1 to connect the L side of the LCR circuit to the power supply Vcc. On the other hand, the drive circuit 53 controls the switching element bridge Tr4 to turn on the R side of the LCR circuit to GND.
4 (a), a positive (a) damped oscillation waveform is electromagnetically injected into the three-phase power supply line 5 from the LCR circuit via the matching transformer 57, as shown in FIG.

On the other hand, when the drive pulse from the inverter 49 is a negative drive pulse that changes from High to Low, the drive circuit 51 controls the switching element bridge Tr2 to be ON and the L side of the LCR circuit is set to GND. Meanwhile, the drive circuit 53 is connected to the switching element bridge Tr3.
By controlling ON of the LCR circuit and connecting the R side of the LCR circuit to the power supply Vcc, as shown in FIG. 4A, the negative vibration waveform of the negative polarity (b) is three-phase from the LCR circuit through the matching transformer 57. Electromagnetically injected into the power line 5. In this way, a positive or negative damped oscillation waveform is electromagnetically applied to the three-phase power line 5 via the matching transformer 57 so as to cancel the negative or positive high-frequency leakage current generated on the three-phase power line 5. The high frequency leakage current generated on the three-phase power supply line can be reduced because the injection is performed in this way.

In this embodiment, since a relatively large current waveform can be directly obtained by using the LCR circuit, there is an advantage that the high frequency amplifier 9 is unnecessary in the circuit. Further, the switching element bridge T is designed to minimize the zero-phase leakage current of the three-phase power supply line 5 detected by the current detection transformer 29.
By variably controlling the collector voltage Vcc of r1 and Tr3 by the control circuit 55, a more stable operation can be obtained. Note that a leakage current reduction effect of 20 dB or more has been confirmed experimentally.

In each of the first to third embodiments, the case where the canceling current is electromagnetically injected into the three-phase power supply line (AC line) has been described, but it is injected into the input DC line of the inverter device. Even if the same effect is obtained. Also, a current detection transformer may be provided in the input DC line. That is, it may be observed that one of the DC line and the AC line has a large value depending on the path through which the leakage current flows. Good.

As described above, according to the present invention, a zero-phase leakage current can be reduced by electromagnetically injecting a current having the same amplitude but opposite phase as a zero-phase current into a three-phase power supply line. Therefore, it is possible to eliminate the radio noise interference caused by the high frequency component of the leakage current. In addition, since a large common mode choke and a common mode transformer as in the prior art are not required and a small and lightweight coil may be used instead, it is particularly advantageous to mount the electric vehicle.

[Brief description of drawings]

FIG. 1 is a diagram showing a system configuration of a high frequency leakage current reduction device 1 according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a system configuration of a high frequency leakage current reduction device 1 according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a logic circuit 21a for one phase, a delay circuit 23a, a waveform generator 25a, and a waveform synthesizer 27, which constitute the high frequency leakage current reduction device 1.

FIG. 4 is a waveform of a zero-phase leakage current observed in a positive (a) or negative (b) damped oscillation waveform and an AC line (c) and a DC power supply line (d) input to the inverter device 3. It is a figure which shows an example.

FIG. 5 is a diagram showing a system configuration of a high frequency leakage current reduction device 1 according to a third embodiment of the present invention.

[Explanation of Codes] 3 Inverter device 5 Three-phase power supply line 7 Current detection coil 7 9 High frequency amplifier 11 Matching coil 13 Three-phase motor

Claims (4)

[Claims] 1. A high-frequency leakage current reducing device in an inverter device for reducing a high-frequency leakage current generated on a three-phase power supply line wired between an inverter device and a three-phase motor, said three-phase power supply being provided. Current detection means for detecting high-frequency leakage current generated on the line, high-frequency amplification means for amplifying the detected high-frequency leakage current, and electromagnetically injecting the amplified high-frequency leakage current into the three-phase power line in reverse phase A high-frequency leakage current reduction device in an inverter device, comprising: an anti-phase injection means. 2. A high-frequency leakage current reducing device in an inverter device for reducing a high-frequency leakage current generated on a three-phase power supply line wired between an inverter device and a three-phase motor, the inside of the inverter device. Current waveform generation means for generating a pseudo high-frequency leakage current waveform in response to a drive pulse for driving the switching element, high-frequency amplification means for amplifying the generated pseudo-high-frequency leakage current, and amplified pseudo high-frequency A high-frequency leakage current reducing device in an inverter device, comprising: an anti-phase injection means for electromagnetically injecting a leakage current into the three-phase power supply line in anti-phase. 3. The inverter according to claim 1, wherein the high frequency amplification means has a control means for controlling an amplification factor so that a high frequency leakage current generated on the three-phase power supply line is minimized. High frequency leakage current reduction device in equipment. 4. The anti-phase injection means has a waveform generation means for generating a positive or negative damped oscillation waveform according to a drive pulse for driving a switching element inside the inverter device. The high frequency leakage current reducing device in the inverter device according to claim 2.