TW201142313A - Device for detecting deterioration in insulation - Google Patents

Abstract

The present invention intends to provide a device for detecting deterioration in insulation, the device being capable of returning quickly to a measurable condition without causing the problem of voltage drift even when a disturbing voltage is applied. Although injected and extracted currents are unbalanced, the current injection and the extraction is executed till a voltage is fixed. Accordingly, when a great disturbing voltage is applied from a direct-current power source side of an insulation condenser, the current extraction or the current injection is executed in the immediately subsequent at the next period so that it is possible to quickly return to the measurable condition without causing the problem of voltage drift.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulation deterioration detecting device for detecting insulation degradation between a vehicle body of an electric vehicle and the like and a high-voltage direct current power source, for example, and a vehicle body. The electrically insulated DC power supply (hereinafter, for convenience of explanation) is also referred to as a high voltage DC power supply, but there is no limit of a few volts or more. [Prior Art] Generally, in an electric vehicle (or a so-called hybrid vehicle) using a high-voltage direct current power source such as a lithium ion battery cell or a super capacitor unit as a driving energy source, in order to prevent electric shock, it is designed to be a high voltage direct current power source. It is electrically insulated from the body at ground potential. However, in the case where the insulation characteristics are deteriorated due to deterioration of the material of the battery pack or the like, the leakage current flowing from the high-voltage DC power source into the vehicle body is transmitted to the human body that touches the vehicle body, which may cause electric shock. Therefore, an electric vehicle needs to be provided with an insulation deterioration detecting device. The inventors of the present invention have proposed an insulation deterioration detecting device. As shown in Patent Document 1, the insulation deterioration detecting device can detect insulation deterioration in a short time or can measure the insulation resistance 値. By using this insulation deterioration detecting device, the driver can confirm that the insulation is not deteriorated in a short time from the time when the engine is turned on, and the driver can be quickly started. [Patent Document 1] Japanese Patent Application No. 2009-102850 No. 201142313 [Problem to be Solved by the Invention] However, in the insulation deterioration detecting device proposed in Patent Document 1, a constant current is intermittently applied to the insulating capacitor at a constant cycle. The injection and extraction are performed. Therefore, when the current balance of the injection and extraction is completely inconsistent, the error is accumulated and a voltage offset occurs. As a countermeasure against this, a voltage dividing resistor is used. In addition, when the main switch is switched from off to on, and a step-like large disturbance voltage is applied from the high-voltage DC power supply side of the insulating capacitor, the range is exceeded, and the insulation resistance cannot be measured in the out-of-range range. value. In the insulation deterioration detecting device proposed in Patent Document 1, after such a large interference voltage is applied, the constant current injection and extraction of the insulating capacitor are alternately performed in a periodic manner, and therefore, the time constant of the circuit is determined by the time constant. After the lapse of time, return to the original measurable state. In addition, there is a case where the insulation is deteriorated after the start of the electric vehicle, and in this case, the user of the electric vehicle or the like may be in danger. Here, after the start of the electric vehicle, it is also necessary to immediately detect the deterioration of the insulation and issue an alarm. Further, although the insulation degradation is not caused by the high-voltage DC power supply, it is desirable to detect the insulation deterioration in the case where the inverter or the motor in the motor drive device of the electric vehicle is deteriorated in insulation. The present invention has been made to solve the above problems, and an object thereof is to provide an insulation deterioration detecting device which does not cause a voltage offset due to error accumulation even when the current balance of injection and extraction is completely inconsistent.

/1 S 201142313 The problem of shifting, in addition, can quickly return to the measurable state when the interference voltage is applied. Another object of the present invention is to provide an insulation deterioration detecting device which can detect the presence or absence of insulation deterioration in a short time after starting of an electric vehicle or the like, or can measure the insulation resistance 在 in a short time. [Means for Solving the Problem] The insulation deterioration detecting device of the present invention is configured as follows. (1) An insulation deterioration detecting device is connected to a DC power source and is composed of an insulating capacitor and a measuring circuit for detecting leakage of a DC power source that electrically insulates a ground portion, and the insulating deterioration detecting device is characterized by: The measuring current system is composed of a constant current alternating circuit and an arithmetic control circuit; the constant current alternating circuit performs the injection and extraction of the constant current of the insulating capacitor in a manner that the peak value of the output voltage becomes a constant voltage. The arithmetic control circuit determines whether or not insulation degradation occurs based on the period of injection and extraction. By designing such a configuration, even if there is an imbalance between the currents to be injected and extracted, current injection and current extraction are performed until a certain voltage is applied, so that the problem of voltage offset does not occur, and thus it is not necessary to The voltage divider resistor of the countermeasure. In addition, even if a large interference voltage is applied from the DC power supply side of the insulating capacitor, the current is drawn to a certain voltage (or current injection) in the cycle immediately after that, so that it can be quickly restored to the original state. Determination status. (2) The constant current altering circuit in the insulating deterioration detecting device of the present invention is characterized in that the maximum peak 値 and the minimum peak 输出 of the output voltage are 2011. Injection and extraction of a constant current of an insulating capacitor. By designing such a configuration, both current injection up to a constant voltage and current extraction up to a constant voltage are performed. Therefore, both the injection time and the extraction time reflect the insulation resistance. (3) The constant current alternating circuit in the insulation deterioration detecting device of the present invention is characterized in that the insulating capacitor is formed such that one of the maximum peak value and the minimum peak value of the output voltage becomes a constant voltage. The constant current is injected and extracted, and the other of the injection and extraction is performed at the same time as the time required for either of the injection and the extraction. By designing such a configuration, only one of current injection up to a constant voltage and current extraction up to a constant voltage is performed, so that the voltage can be easily detected. (4) The constant current alternating circuit in the insulation deterioration detecting device of the present invention is specifically configured such that both the maximum peak value and the minimum peak value of the output voltage become positive voltage or negative voltage. Injection and extraction of a constant current to the insulating capacitor are performed. By designing such a configuration, a constant current alternating circuit can be constructed with a single power source. The maximum peak 値 can be set to a positive voltage, the minimum peak 値 can be set to 0V, the maximum peak 値 can be set to OV, and the minimum peak 値 can be set to a negative voltage. (5) The insulation deterioration detecting device of the present invention is characterized in that a Zener diode is further provided which limits the output voltage to the maximum driving voltage of the constant current alternating circuit.

S 201142313 By designing such a configuration, even if a large interference voltage is applied, the constant current altering circuit can be operated, and the original measurable state can be quickly restored. (6) The insulation deterioration detecting device of the present invention is characterized in that the number of injections and extractions required for determining the insulation deterioration of the measuring circuit is set to be smaller than when the machine is to be started when the machine to be measured is started. By designing such a configuration, the insulation deterioration can be quickly determined when the device to be measured is started, and the insulation deterioration can be determined in consideration of possible interference during the operation of the device. (7) An insulation deterioration detecting device for detecting insulation degradation in a motor driving device, the motor driving device having: a DC power source electrically insulated from the ground portion; the motor is powered by the power from the DC power source And a power converter that converts power from the DC power source into power suitable for driving the motor; the insulation degradation detecting device is characterized in that: a measuring circuit is provided, and the measuring circuit is connected to the DC power source The insulation resistance 値 in the motor drive device is measured; the measurement circuit has a high frequency discrimination circuit that restricts the inflow of the high frequency component of the operation of the power converter toward the measurement circuit. By designing such a configuration, the power converter can be operated without any influence of high-frequency components, and the insulation resistance 値 can be accurately measured by the measurement circuit provided on the DC power supply side, and the motor drive can be detected. The insulation of the device is degraded. (8) The insulation deterioration detecting device of the present invention is characterized in that, in particular, the 201142313 high-frequency discrimination circuit is a low-pass filter that forms a closed-loop with the power converter and the motor for the high-frequency component generated by the power converter. In the circuit, the cutoff frequency is set to be higher than the frequency of the injection and extraction operations of the constant current of the measurement circuit, and is lower than the frequency of the high frequency component generated by the power converter. By designing such a configuration, the high-frequency component flows into the measurement circuit during operation of the power converter, and is also blocked by the low-pass filter. The frequency component of the injection and extraction operation of the constant current of the measuring circuit is used to measure the insulation resistance of the measuring circuit, thereby detecting the insulation deterioration of the motor driving device. (9) Further, the insulation deterioration detecting device of the present invention is characterized by, for example, a 'motor-based alternating current motor, a power converter-based inverter; and a high-frequency-separating circuit for limiting the high force generated by the operation of the inverter. The inflow of the frequency component toward the measuring circuit* is designed such that even when the inverter operates, the high-frequency component generated by the inverter flows into the measuring circuit, and the high-frequency becomes a distinguishing circuit (for example, low) Pass filter). Therefore, it is not affected by high-frequency components. 'The insulation resistance 値 can be accurately measured by the measurement circuit provided on the DC power supply side, and the insulation deterioration of the motor drive device can be detected.> In the motor-based DC motor, power conversion In the case of a chopper circuit, the present invention is equally applicable, and the inflow of the high-frequency component generated by the chopper circuit toward the DC power source side is limited by a high-frequency discrimination circuit (for example, a low-pass filter). (10) Here, the inventors have considered that the case where the power converter is an inverter and the 201142313 PWM control the inverter has a high-frequency component which is a V-shaped wave generated under the PWM control of the inverter. Here, the high-frequency discrimination circuit (for example, a low-pass filter) is configured as a V-shaped wave discrimination circuit for limiting the inflow of the high-frequency component of the V-shaped wave toward the DC power supply side. By designing such a configuration, even when the inverter is operated, it is not affected by the high-frequency component, and the insulation resistance 値 can be accurately measured by the measurement circuit provided on the DC power supply side, and can be detected. The insulation of the motor drive device is deteriorated. [Effect of the Invention] According to the present invention, it is possible to provide an insulation deterioration detecting device which does not require a voltage offset countermeasure due to the imbalance of injection and extraction of current, and can reduce the unmeasurable cause of interference. The time of the state. Further, according to the present invention, it is possible to provide an insulation deterioration detecting device which can detect the presence or absence of insulation deterioration after the start of an electric vehicle or the like, or can measure the insulation resistance 値. [Embodiment] Hereinafter, an embodiment of an insulation deterioration detecting device of the present invention will be described with reference to the accompanying drawings. First, before describing the configuration of the insulation deterioration detecting device according to the embodiment of the present invention, the overall configuration of the insulation deterioration detecting device 10 and the high voltage circuit 15 in the electric vehicle will be described with reference to Fig. 1 . The high-voltage circuit 15 shown in Fig. 1 is a high-voltage DC power source 16 for generating a high voltage by stacking a lithium ion battery cell and a supercapacitor cell, a main switch 17 , an inverter 18 , and an AC motor 19 . Composition.

S 201142313 The measurement circuit 12 is connected to a 12 V power supply used in an ordinary automobile including an electric vehicle, and is configured to output an alarm signal when the insulation deterioration is detected or when the insulation resistance 値 becomes a predetermined value or less. . If it is designed to detect that the insulation resistance 値 is less than or equal to a predetermined value in the pre-stage of insulation failure that does not reach the degree of insulation degradation, an insulation deterioration detection with higher reliability can be performed. Further, the measuring circuit 12 can monitor the insulation resistance 时 from time to time, and when the insulation resistance 値 is lower than the set resistance 値, it outputs a warning signal or an alarm signal. The high-voltage DC power supply 16 is insulated from the vehicle body at the ground potential, that is, the chassis, in order to prevent electric shock. Here, the insulation resistance (insulation resistance) and Cx indicate stray capacitance. Fig. 2 shows the principle of the insulation deterioration detecting device of the constant current alternating mode. First, during the injection of the constant current, the constant current alternating circuit 20 reverses the direction of the constant current 1 按照 for each sampling period Ts by a current conversion signal from an arithmetic control circuit (not shown). The injection and extraction operations of the constant current 1 朝 of the insulating capacitor 1 l (Ci), the insulation resistance Rx, and the stray capacitance Cx are repeatedly performed. Here, the sampling period Ts is set to be a multiple of the time constant (TX = CxRx) of the circuit (Ts >> τ χ). Fig. 3 shows the output voltage Vout of the constant current alternating circuit 20 in the injection period (+1 〇 period) of the constant current and the extraction period (-1 〇 period). Vci is the voltage between the terminals of the insulated capacitor 'Vex is the stray capacitance voltage. The output voltage v 〇 ut of the +1 〇 period when the current is reversed is expressed by the following equation 1 and the output voltage Vout of the period ’ Ι is expressed by the following Equation 2. Where ' -10- 201142313 sets the residual voltage of Ci to Vci〇. Further, 'Vout(nTs) => Vout(n) is simply indicated. [Formula 1].

Vcu, («) = VCX (n) + VC (M) =^TS+ Kw + Rxh (1 _ £'TS,TX )=~^rTS+ VClO +

Cl C1 [Expression 2]

Kul (« + !) = Va (n + l) + Va (n + l) = VCi0 - RI0 (1 - ε~τ^ )2 - Vcl0 - RI0 Then, in order to cancel the residual voltage Vcio of Ci, take a positive peak The absolute 値Vo lit PP of the difference between the 値 voltage and the negative peak , voltage is calculated by Equation 3 to calculate the resistance 値RCx. Then, the calculated resistance 値RCx can be expressed by Equation 4. [Expression 3] KUIPP = K («) - Kul (η +1)1 = Ί rs + 2RXI0 (1 - ) - ^/0 (1 - )s-T^- Let s+2RxI. [Expression 4] v PP T f ^ 1 Λ RC v_^L__L_ = r \-±£~^ +l£-^ ^ f. V2C, 丄2, 2h, calculate the resistance 値y, sell the resistor iv, calculate the polynomial of the resistance 値, and calculate the resistance 値RCx, which is calculated from VontPP using the equation of the calculated resistance ,, which is also the exponential function. The polynomial is multiplied by the actual resistance 値Rx. Here, if Ts >> τ χ, the polynomial of the exponential function is close to 1, so that the actual insulation resistance R X can be calculated with sufficiently high accuracy in calculating the resistance 値RCx. For example, if T s = 3 τ X, it can be calculated as -11-201142313 with an accuracy of 90%, and Ts = 4tx, which can be calculated with an accuracy of 97.3%. If Τπ5τχ, it can be calculated with an accuracy of 99.0%, Ts = 6tx can be calculated with an accuracy of 99.6%, and TS = 7τx, which can be calculated with an accuracy of 99.9%. Then, if the sampling period Ts is extended, the accuracy becomes higher, but it is known that the accuracy obtained by Τδ = 3τχ is sufficient in practical use, and the sampling period (Ts) is set to be able to be detected in a short time. It is preferable that at least three times or more of the time constant (τ χ) of the circuit to be measured. That is, the calculation of the resistance 値RCx is based on the assumption that the peak-to-turn voltage VoxitPP can be accurately measured as a correct calculation. Fig. 4 shows a configuration in which the insulation deterioration detecting device of the constant current alternating mode shown in Fig. 2 is designed to be more practical. In Fig. 4, a voltage dividing resistor 41 and a Zener diode 42 are added. When the insulation is normal, that is, when the insulation resistance Rx is large, the output voltage VoutPP is increased, so that the constant current cannot be flown from the driving power source of the constant current alternating circuit 20. Here, when the output voltage VoutPP is increased, the output voltage VoutPP can be suppressed to a certain voltage I 〇 Rm or less by increasing the current flowing through the voltage dividing resistor 4 1 and reducing the current flowing through the insulation resistance RX. In addition, there is a case where the variation of the high-voltage DC voltage source is extremely large. When the motor is started, when the light load of the motor is converted to full load, when the motor is stopped, or when the rapid charging mode is switched to the high-voltage DC voltage source, a large current flows out to the high-voltage DC voltage source in a short time. Inflow/stop. As a result, the voltage variation of the high voltage DC voltage source also increases. This will become an important factor in the measurement accuracy of the insulation resistance. Moreover, when the voltage of the high-voltage DC voltage source is high, there will be a case where the maximum driving voltage (±VDD) of the constant current circuit exceeds -12-5 201142313, which may cause an oscillation phenomenon. In the worst case, the constant current circuit may be exceeded. It is resistant to voltage and 'causes damage. As a countermeasure, a Zener diode is placed to limit the upper and lower limits of the output voltage vout. The Zener voltage VZ of the inserted Zener diode is selected to satisfy the condition of VDD > VZ > IoRm. In this configuration, the insulating capacitors are alternately injected and extracted at regular intervals. Therefore, when the current balances of the injection and extraction are completely inconsistent, the error is accumulated and a voltage shift occurs. As a countermeasure against this, a voltage dividing resistor 4 1 is used. Fig. 5 is a view showing a voltage waveform of the operation of the measuring circuit 12 in Fig. 4 when a stepped large disturbance voltage is applied from the high voltage direct current power source side of the insulating capacitor. In Fig. 5, the constant current alternating circuit 20 is between the maximum peak voltage 4V and the minimum peak voltage -4V in a period from 0 seconds to 5 seconds, each in 0.2 seconds. The injection and extraction operations are performed. At the time of 5 seconds elapsed, when an interference voltage of, for example, 5 OV is applied, this is reduced by the action of the Zener diode 42, but the output voltage of the constant current altering circuit 20 becomes, for example, 12V. Each of the operations of injecting and extracting in 0:2 seconds causes the peak-to-peak voltage to gradually decrease. In the example of Fig. 5, after about 20 seconds, the state before the application of the interference voltage is restored. The configuration of the insulation deterioration detecting device 70 according to the first embodiment of the present invention will be described with reference to Fig. 6 . In Fig. 6, the insulation deterioration detecting device 70 is composed of a computer-made arithmetic control circuit 71, a constant current alternating circuit 72, and a Zener diode 73 for circuit protection. Constant current alternating circuit 72

-13 - S 201142313 is a direction of current (1〇) by a current conversion signal from the arithmetic control circuit 71. Here, the 値Ci of the insulating capacitor 11 is set to be 10 times or more larger than the capacitance 値Cx. The insulation between the measuring circuit and the high-voltage DC voltage source is ensured by the insulation _ @ ^ 11. The range of the measurable gastric voltage DC voltage is determined by the withstand voltage of the insulating capacitor 11, which is a component requiring high reliability. As the insulating capacitor 11, it is preferable to have high-temperature resistance characteristics and characteristics, and the failure mode is open. The insulating deterioration detecting device 70 is a hard body, and can be composed of a general automobile specification product (withstand voltage of 60 V or less) except for the insulating capacitor g 1 1 , and it is not necessary to use a high-priced special specification product. A single-chip microcomputer with a built-in data flash memory and a 10-bit high-speed AD converter can be used in the digital unit. In the power supply unit, the reverse power supply can be implemented by generating a stabilized power supply that supplies the supply voltages DC8 to 1 6 V to the digital unit and the analog unit. The consumption current can be set to 150 mA or less as a low power consumption. In the actual device, the installation position can be set in the battery pack, and the maximum operation guaranteed temperature can be set to 85 °C. In addition, although the series communication and operation check terminals of CAN and RS 2 3 2 C are built in for evaluation, they may be configured not to be connected to the connector pins. At the time of mass production, miniaturization of the device can be achieved by removing these functions. Next, the operation of the insulation deterioration detecting device 70 will be described with reference to Figs. 7 to 10 . Here, Figure 7 shows that the insulation resistance 値 is 500kii, the upper limit is

S -14-201142313 The voltage waveform of the injection and extraction operation of the insulation deterioration detecting device 70 when the voltage Vh is 5 V and the lower limit voltage VL is 〇V. Further, Fig. 8 shows a voltage waveform of the injection and extraction operation of the insulation deterioration detecting device 70 when the insulation resistance 値 is 100 Ω, the upper limit voltage VH is 5 V, and the lower limit voltage is 〇 ν. In addition, Fig. 9 is a schematic view of Fig. 7, and Fig. 10 is a schematic view of Fig. 8. First, as shown in FIG. 9, during the injection of the constant current, the constant current altering circuit 72 reverses the direction of the constant current 1 藉 at time T! by the current switching signal from the arithmetic control circuit 71. The constant current Ιο is injected into the insulating capacitor 1 1 (electrostatic capacitance 値Ci ) 'insulation resistance Rx, stray capacitance Cx. When the arithmetic control circuit 71 detects that the output voltage V〇ut reaches a positive constant voltage (upper limit voltage VH), the current conversion signal that reverses the direction of the constant current 1〇 is supplied to the constant current alternating circuit 72. The current is drawn out. When the arithmetic control circuit 71 detects that the output voltage Vout has reached a negative constant voltage (lower limit voltage VL), the current conversion signal that reverses the direction of the constant current 1 供给 is supplied to the constant current alternating circuit 72 to perform current. Injection. That is, the switching control of the injection and extraction of the constant current Ιο by the current alternating circuit 72 is performed as follows. • After the current is drawn to lower the output voltage Vout to the lower limit voltage VL, it is converted into current injection (time ΤΊ, T3, T5). • After current injection is performed to increase the output voltage Vout to the upper limit voltage VH, it is converted to current extraction (times T2, T4, and T6). The arithmetic control circuit 7 1 measures the following injection time and extraction time. -15- 201142313 • Injection time = Τ 1~Τ 2 time, Τ 3~Τ 4 time, Τ 5 ～τ6 time... • Extraction time = time between τ2~τ3, τ4~τ5 Time, time between τ6 and τ7... According to the injection extraction period (injection time + extraction time), the magnitude of the insulation resistance 値 is determined. As can be seen from Fig. 10, when the insulation resistance is small, the injection time (time between τ! and τ2) and the extraction time (time between τ2 and τ3) become long, and therefore the injection extraction period becomes long. Therefore, by measuring the injection extraction period, the insulation resistance 値 can be indirectly measured, and the insulation deterioration can be judged. For example, the injection extraction period corresponding to the predetermined insulation resistance 値 is set to a critical value, and if the measured injection extraction period reaches the critical value, it is judged that the insulation is deteriorated. According to the insulation deterioration detecting device 70', for example, even when the current balance of the injection and extraction has a large error, the current is injected and extracted until the output voltage becomes a constant upper limit voltage VH and lower limit voltage VL. Therefore, the problem of voltage offset does not occur 'and thus does not need to set the voltage dividing resistor as shown in Fig. 4. The error of the current balance occurs as an error corresponding to the injection and extraction time, which is only a measurement error as an insulation resistance. The determination of the presence or absence of insulation deterioration does not require the measurement of the high-precision insulation resistance ’, so that it does not become a problem in practical applications. Fig. 11 shows that an interference voltage is applied to the insulation deterioration detecting device 70

-16- S The voltage waveform of the current injection and extraction operation in the case of 201142313. In Fig. 11, the constant current alternating circuit 70 is at the upper limit voltage (maximum peak voltage) 5v and the lower limit voltage (minimum peak voltage OV) OV from the time of the leap second to the time of 5 seconds elapsed. Injection and extraction operations are performed between them. At the time of 5 seconds elapsed, when an interference voltage of, for example, 50 V is applied, the output voltage of the constant current altering circuit 72 becomes, for example, 1 2 V, although it is reduced by the action of the Zener diode. Since the voltage is equal to or higher than the upper limit voltage VH, the constant current altering circuit 72 performs the extraction operation, and when the lower limit voltage V1 is reached, the constant current altering circuit 72 performs the injection operation. As described above, even when a large disturbance voltage is applied, the constant current altering circuit 72 performs the extraction operation to the lower limit voltage V1, and the normal operation can be resumed at once. In the case of Fig. 1, the time required to return to the state before the application of the interference voltage is about 5 seconds, which is considerably shortened compared with the case shown in Fig. 5. Fig. 12 shows a second example of the injection and extraction operation of the constant current by the insulation deterioration detecting device 70. In this case, the switching control of the constant current alternating circuit 72 is performed as follows. • After the current is injected to increase the output voltage V out to reach the upper limit voltage VH, it is converted to current extraction (times T2, T4, T6). • After conversion, after the time equal to the closest current injection time, it is converted into current injection (time Τ丨, Τ3, Τ5). The arithmetic control circuit 7 1 measures the following injection time. • Injection time = Τ, ~ Τ 2 time, Τ 3 ~ Τ 4 time, Τ 5 ~ Τ 6 time... -17- £ 201142313 • Extraction time = the closest injection time according to this injection extraction cycle (injection time + Take time) = (2χ injection time), determine the size of the insulation resistance 値. In this case, the maximum peak 输出 of the output voltage V out of each cycle is equal to the upper limit voltage V η , but the minimum peak 不 is not equal to the same voltage due to the imbalance of the currents injected and extracted. As in this example, the magnitude of the insulation resistance 値 can be determined based only on the injection time of the current. Fig. 13 shows a third example of the injection and extraction operation of the constant current by the insulation deterioration detecting device 70. In this case, the switching control of the constant current alternating circuit 72 is performed as follows. • After the current is drawn to lower the output voltage Vout to reach the lower limit voltage VL, it is converted into current injection (times T!, T3, TS). • After the conversion, after the time equal to the closest current extraction time, it is converted to current extraction (times T2, T4, T6). The arithmetic control circuit 7 1 measures the following extraction time. . Extraction time = time between Τ2 and Τ3, time between Τ4 and Τ5, time between Τ6 and Τ7... • Injection time = closest extraction time according to this injection extraction period (injection time + extraction time) = (2χ extraction Time), determine the size of the insulation resistance 値. In this case, the minimum peak 输出 of the output voltage v 〇ut of each cycle is equal to the lower limit voltage VL, but the maximum peak 不 is not equal to the same voltage due to the current imbalance of the injection and extraction. As in this example, the insulation resistance 値 can be judged based only on the current extraction time -18 - 5 201142313. In the injection and extraction operation of the currents shown in FIGS. 7 to 8 and 12 and 13 , the upper limit voltage VH is set to a positive voltage and the lower limit voltage VL is set to a negative voltage. In the case shown in Fig. 11, a single power source, for example, the upper limit voltage VH may be set to a positive voltage, and the lower limit voltage V1 may be set to ον. Further, the lower limit voltage vL may not be set to ον, but may be set to a positive voltage. In this case, one of the protection Zener diodes 83 shown in FIG. 14 may be provided in the opposite direction shown in FIG. 6 instead of the two Zener diodes for protection connected in series. 73. Further, the upper limit voltage ν 〇 may be set to 〇V' to set the lower limit voltage VL to a negative voltage, or the upper limit voltage VH may be set to a negative voltage without being set to 0V. In the present case, the [injection extraction cycle] includes: the sum of the injection time and the extraction time, only the injection time, only the extraction time, the multiples of these, or a combination thereof. In the above description, although [positive voltage] and 0V and [negative voltage] are distinguished from 0V, in the present case, the case where [positive voltage] includes ον may be used. There may also be cases where [negative voltage] contains 0V. In the determination of the deterioration of the insulation, the number of injection extraction cycles which are the basis of the determination can be changed before and during the start of the operation of the device (including the inverter or the like). This is the case where the magnitude of the disturbance voltage is different before and during the start of the machine. For example, the following judgment can be made. Before starting the machine (small interference voltage): The insulation deterioration is judged by the average 値 or cumulative 注入 of the injection extraction cycle measured for the first or second to third times of the injection -19-201142313. When the machine is operating (interference voltage is large): The insulation deterioration is judged by the average 値 or cumulative 注入 of the injection extraction period measured for a plurality of injection extraction operations. According to the above configuration, it is possible to determine whether or not the insulation deterioration is high at a high speed before the start of the machine, and it is possible to judge whether or not the insulation deterioration is caused while reducing the influence of the interference voltage during the operation of the machine. As shown in the previous application, it can be seen from the insulation deterioration detecting device shown in FIGS. 1 to 4 that the inverter can be detected before the start of the inverter of the electric vehicle, that is, until the main switch 17 is turned on. The presence or absence of insulation degradation of the DC circuit portion. Here, the main switch 17 is turned on, and the influence on the insulation deterioration detection after the inverter 18 and the AC motor 19 are driven is investigated. Fig. 15 shows the time variation of the output voltage Vout before and after the inverter 18 is driven, and Fig. 16 is a partially enlarged view thereof. As shown in Figs. 15 and 16, the output voltage is changed at a low frequency and a small amplitude according to the injection and extraction of the constant current before the inverter 18 is driven. Further, after the driving of the inverter 18, as shown in the figure, a voltage having a large amplitude of a high frequency was observed. The inventors of the present invention examined the causes of such high-frequency and large-amplitude voltages after the inverter 18 was driven. Figure 17 shows the high voltage circuitry of an electric car. In Fig. 17, the high voltage circuit 15 is, for example, a motor drive device for an electric vehicle, and the high voltage circuit 15 is composed of a high voltage direct current power source 16, a main switch 丨7, an inverter 18, and an alternating current motor 119. High here

-20- S 201142313 The DC section of the voltage circuit system has a high voltage DC power supply 16 and a main switch 17, which has an AC motor 19 in the AC section. The inverter 18 converts DC power from the DC unit (high-voltage DC power source 16) into AC power during operation, and supplies it to the AC unit (AC motor 19), and converts the AC power of the AC unit to DC during regeneration. Electricity is supplied to the DC section. However, the 'AC motor 19' is driven by PwM control according to the triangular wave comparison method, and the waveform of each part is as shown in Fig. 18. (a) Display triangular transport wave, U phase modulated wave, V phase modulated wave, w phase modulated wave; (b) Display U phase voltage, V phase voltage, W phase voltage; (c) Display U - V line Inter-voltage, VW line voltage ' WU line voltage. Therefore, the voltage Vpc at the lowest potential portion of the high-voltage DC power supply 16 in Fig. 17 is a waveform called a V-shaped wave as shown in Fig. 19. As a result of the comparison, it is conceivable that the observed waveforms shown in Figs. 15 and 16 may be caused by V-shaped waves. In addition, it is conceivable that the V-shaped wave generated by the inverter may be transmitted to the DC portion via the ground (chassis) to affect the output voltage. The insulation deterioration detecting device according to the second embodiment of the present invention includes a V-shaped wave discriminating circuit that removes the influence of the V-shaped wave. Fig. 20 is a view showing the configuration of an insulation deterioration detecting device of this embodiment. In Fig. 20, the description of the same components as those shown in Fig. 4 (the constant current alternating circuit 20, the insulating capacitor 1 1 , the voltage dividing resistor 41, and the Zener diode 42) will be omitted. In Fig. 20, the V-shaped wave discriminating circuit 50 is provided between the insulating capacitor 11 and the constant current alternating circuit 20. The V-shaped wave discrimination circuit 50 does not affect the output voltage v〇ut of the insulation degradation detecting device from the tube frequency component transmitted from the AC-21 - 5 201142313. Fig. 21 shows an example of a specific circuit of the V-shaped wave discriminating circuit 50. In Fig. 21, the V-shaped wave discrimination circuit 50 is a low-pass filter 6A, and is composed of a resistor 61 and a capacitor 62. The low-pass filter 6 is provided between the insulating capacitor 11 and the constant current alternating circuit 20, and functions to allow low-frequency components to pass but to block high-frequency components. The resistance 値 and the electrostatic capacitance 电阻 of the resistor 61 and the capacitor 62 are set such that the cutoff frequency of the low-pass filter 60 is lower than the frequency of the V-shaped wave and the frequency of the constant current injection circuit 20 is injected and extracted. (The above is explained by the cycle) is high. The frequency at which the constant current is converted and extracted by the constant current alternating circuit 20 is, for example, several Hz, and the frequency of the V-shaped wave is, for example, several KHz. Therefore, when viewed for high-frequency components, the V-shaped wave discriminating circuit 50 forms a closed loop with the inverter 18 and the AC motor 19 so that the high frequency component of the v-shaped wave does not affect the output voltage Vout. Therefore, after the inverter is started, the insulation resistance 値 can be accurately measured, that is, the correct insulation degradation can be detected. Further, in this case, not only the insulation deterioration of the high-voltage DC power source 16 in the high-voltage circuit 15 but also the insulation deterioration of the inverter 18 and the AC motor 19 can be detected. Further, the V-shaped wave discriminating circuit 50 can be applied not only to the insulating deterioration device described with reference to Figs. 2 to 4, but also to the insulating deterioration device described with reference to Figs. 6 to 14 . The present invention is not limited to the insulation deterioration device for a motor vehicle of an electric vehicle or a hybrid vehicle, and can be applied to a system for power storage such as a wind power generation, a solar power generation, a fuel cell, or the like, for example, in a capacitor. In the case where such a high-voltage DC power source is connected to a power system through a system-connected inverter or the like, it is also possible to determine the insulation degradation between the high-voltage DC power source and the casing. When the frame is connected to the ground wire of the ground, it can be judged when the device for isolating the high-voltage DC power source from the power system is stopped, and when the frame is not connected to the ground wire of the ground, the device can be operated. Make a judgment. [Industrial Applicability] The present invention can detect insulation degradation of a power system using a high voltage direct current power source, for example, a power source and a drive device of an electric car or a hybrid car, a wind power generation, a solar power generation, a fuel cell, or the like. Further, the present invention can be used in a motor drive device for an electric vehicle or a hybrid vehicle including a high-voltage circuit including a high-voltage DC power supply, an inverter, a motor, etc., and can also detect the presence or absence of insulation degradation after the start of the inverter. . BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing the overall configuration of an insulation deterioration detecting device and a motor driving device for measuring an insulation resistance according to the present invention. Table 2 is an equivalent circuit of the insulation deterioration detecting device which does not apply the constant current alternating mode of the present invention. FIG. 3 is a view showing the output of the current injection and extraction operation of the insulation deterioration detecting device shown in FIG. Voltage waveform diagram. Fig. 4 is a view showing the configuration of the insulation deterioration detecting device -23- 1 201142313 proposed by the inventors of the present invention. Fig. 5 is a view showing a voltage waveform of a constant current injection and extraction operation in the case where an interference voltage is applied in the insulation deterioration detecting device of the prior art. Fig. 6 is a schematic view showing the configuration of an insulation deterioration detecting device according to the first embodiment of the present invention. Fig. 7 is a view showing the voltage waveform of the constant current injection and extraction operation when the insulation resistance 値 is 50 OkQ. Fig. 8 is a view showing a voltage waveform of a constant current injection and extraction operation when the insulation resistance 値 is 10 OkQ. Figure 9 is a schematic diagram of Figure 7. Figure 10 is a schematic diagram of Figure 8. Fig. 1 is a view showing a voltage waveform of a constant current injection and extraction operation when an interference voltage is applied in the insulation deterioration detecting device according to the first embodiment of the present invention. Fig. 1 is a schematic diagram showing a voltage waveform at the time of the injection/extraction operation in which only the upper limit voltage is set to a constant voltage by the constant current alternating circuit shown in Fig. 6 in the case where the insulation resistance is large. In the case of the case where the insulation resistance is large, the constant current alternating circuit shown in Fig. 6 is a schematic diagram of the voltage waveform at the time of the injection and extraction operations in which only the lower limit voltage is set to a constant voltage. Fig. 14 is a view showing the connection of the -24-201142313 nano-polar body of the insulating deterioration detecting device when the maximum peak 値 is a positive voltage and the minimum peak 値 is 〇V. Fig. 15 is a waveform diagram showing output voltages before and after the inverter is started in the insulation deterioration detecting device shown in Fig. 2. Fig. 16 is a partially enlarged view showing the inverter when the output voltage waveform diagram shown in Fig. 15 is started. Fig. 17 is a view showing the configuration of an example of a motor driving device. Figure 18 is an explanatory diagram showing the PWM control of the inverter. Fig. 19 is a waveform diagram showing a V-shaped wave generated by PWM control by a converter. Fig. 20 is a view showing the configuration of an insulation deterioration detecting device according to a second embodiment of the present invention. Fig. 2 is a circuit diagram showing an example of a v-shaped wave discriminating circuit shown in Fig. 2 . Fig. 22 is a diagram showing waveforms of output voltages before and after the start of the inverter in the insulation deterioration detecting device shown in Fig. 20. [Main component symbol description] 10 Insulation deterioration detection device 1 1 Insulation capacitor 12 Measurement circuit 13 Sensing terminal 15 High voltage circuit 16 Commercial voltage DC power supply 17 Main switch 1 8 Inverter 19 AC motor-25- 201142313 20 Constant current Alternating circuit 4 1 voltage dividing resistor 42 Zener diode 50 V wave discriminating circuit 60 low pass filter 6 1 resistor 62 capacitor 70 insulation deterioration detecting device 7 1 arithmetic control circuit 72 constant current alternating circuit 73 Zener diode 83 Zener diode -26- 5

Claims (1)

201142313 VII. Patent application scope: 1. An insulation deterioration detecting device is connected to a DC power source, and is composed of an insulating capacitor and a measuring circuit for detecting leakage of the DC power source electrically insulating the grounding portion, the insulation The deterioration detecting device is characterized in that: the measuring current is composed of a constant current alternating circuit and an arithmetic control circuit; and the constant current alternating circuit is configured such that a peak value of the output voltage thereof becomes a fixed voltage, and interactively The constant current injection and extraction of the insulating capacitor are performed. The arithmetic control circuit determines the insulation degradation based on the period of the injection and extraction. 2. The insulating deterioration detecting device according to claim 1, wherein the constant current alternating circuit is interactively performed in such a manner that both the maximum peak value and the minimum peak value of the output voltage become a certain voltage. The constant current of the insulating capacitor is injected and extracted. 3. The insulation deterioration detecting device according to claim 1, wherein the constant current alternating circuit is configured such that one of a maximum peak value and a minimum peak value of the output voltage becomes a constant voltage The injection current and the extraction of the constant current of the insulating capacitor are performed in the same manner as the time required for either of the injection and the extraction. 4. The insulation deterioration detecting device according to any one of claims 1 to 3, wherein the constant current alternating circuit is a positive voltage or both of a maximum peak value and a minimum peak value of the output voltage thereof In the negative voltage mode, the constant current injection and extraction of the insulating capacitor are performed in place -27- 5 201142313. 5. The insulating deterioration detecting device of any one of claims 1 to 4, wherein a Zener diode is further provided, the Zener diode system limiting an output voltage to the constant current alternating circuit The maximum drive voltage is below. (6) The insulation deterioration detecting device of any one of the first to fifth aspects of the invention, wherein the number of injections and extractions required for determining the insulation deterioration of the measurement circuit is set to be Less than when the machine is moving. 7. An insulation deterioration detecting device for detecting insulation degradation in a motor driving device, the motor driving device having: a DC power source electrically insulated from a ground portion; the motor is powered by the power from the DC power source And a power converter for converting power from the DC power source into power suitable for driving the motor; the insulation degradation detecting device is characterized by: having a measuring circuit connected to the DC power source And measuring the insulation resistance 値 in the motor driving device; the measuring circuit has a high frequency forming circuit for limiting the inflow of the high frequency component of the operation of the power converter toward the measuring circuit* 8 An insulation deterioration detecting device according to claim 7, wherein the high frequency discrimination circuit is a low pass filter, and a high frequency component generated by the power converter is closed with the power converter and the motor Back to -28-201142313, the cutoff frequency is set to be higher than the injection and extraction of the constant current of the measurement circuit. And a low frequency component of the generated high-frequency ratio of the power converter. 9. The insulation deterioration detecting device according to claim 7 or 8, wherein the motor is an AC motor, and the power converter is an inverter; the high frequency discrimination circuit limits the action of the inverter The generated high frequency component flows into the measurement circuit. The insulation deterioration detecting device according to any one of claims 7 to 9, wherein the high frequency component is a V-shaped wave generated by PWM control of the inverter. S -29-