WO2019123618A1 - Zero-crossing detection device and power conversion device - Google Patents

Zero-crossing detection device and power conversion device Download PDF

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Publication number
WO2019123618A1
WO2019123618A1 PCT/JP2017/045998 JP2017045998W WO2019123618A1 WO 2019123618 A1 WO2019123618 A1 WO 2019123618A1 JP 2017045998 W JP2017045998 W JP 2017045998W WO 2019123618 A1 WO2019123618 A1 WO 2019123618A1
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Prior art keywords
power supply
detected
supply voltage
half wave
point
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PCT/JP2017/045998
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French (fr)
Japanese (ja)
Inventor
公輔 小山
達也 前川
宏気 鹿屋
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東芝キヤリア株式会社
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Priority to PCT/JP2017/045998 priority Critical patent/WO2019123618A1/en
Publication of WO2019123618A1 publication Critical patent/WO2019123618A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/175—Indicating the instants of passage of current or voltage through a given value, e.g. passage through zero
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode

Definitions

  • the present invention relates to a zero-crossing detecting device for detecting a zero crossing point of an AC power supply voltage, and a power conversion device provided with the zero-crossing detecting device.
  • the zero cross point of the AC power supply voltage is detected to improve power factor and suppress harmonic current, and the switching element is turned on based on the detected zero cross point,
  • the off operation timing is determined. For example, in a high power factor power supply circuit, a short circuit to an AC power supply is formed through the reactor for a predetermined period based on the zero crossing point.
  • the zero cross point of the AC power supply voltage is detected using a photocoupler.
  • the photocoupler used to detect the zero cross point has a rapid rise in output voltage when a current flows through the light emitting element and the light receiving element is turned on, but the output voltage when the light emitting element is turned off and the light receiving element is turned off There is a characteristic that falling is slow. If the on / off state of the photocoupler is detected as the zero cross point of the AC power supply voltage, an error occurs in the detection. As a result, the power converter can not obtain the originally intended power factor improvement and harmonic current suppression effects. In addition, when both positive and negative zero crossings of the AC power supply are detected, a current always flows through the photocoupler in a period excluding the vicinity of the zero crossing, which leads to power loss.
  • An object of the zero-crossing detecting device is to capture the zero-crossing point of the AC power supply voltage efficiently and accurately without error.
  • the zero-crossing detection apparatus includes a photocoupler and an operation unit.
  • the photocoupler has a light emitting element which emits light by a half wave of an AC power supply voltage and a light receiving element which is turned on in response to the light emission of the light emitting element.
  • the operation unit sequentially detects the rising point of the half wave of the AC power supply voltage from the output of the photocoupler, and among the detected rising points, the rising point detected last and the rising point detected one before the last Time interval is detected as the cycle of the alternating current power supply voltage, and the time point when the half of the detected cycle is added to the last detected rising point is the alternating current after the last detected rising point
  • the point at which the zero crossing point of the first half wave of the power supply voltage is estimated, and the point at which the detected period is added to the last detected rising point is estimated as the zero crossing point of the next half wave of the first half wave.
  • FIG. 1 is a block diagram showing the configuration of one embodiment.
  • FIG. 2 is a diagram showing a waveform of an AC power supply voltage, a waveform of an output voltage of a photocoupler, and a waveform of an input voltage to a computing unit in one embodiment.
  • FIG. 3 is a flowchart showing processing of the computing unit in one embodiment.
  • the input end of the converter 2 is connected to the L phase and the N phase of the AC power supply 1, and the input end of the inverter 3 is connected to the output end of the converter 2.
  • the output terminal of the inverter 3 is connected to a brushless DC motor 4 for driving a compressor.
  • Converter 2 includes a reactor 11 disposed in a power supply line connected to L phase of AC power supply 1, a short circuit 12 connected between L phase and N phase of AC power supply 1 via reactor 11, and the above reactor 11.
  • the short circuit 12 includes a bridge circuit of four diodes 12a to 12d and one switching element such as an IGBT (Insulated Gate Bipolar Transistor) 12t.
  • IGBT Insulated Gate Bipolar Transistor
  • Inverter 3 converts the output voltage of converter 2 (voltage of smoothing capacitor 14) into AC voltage of a predetermined frequency by switching according to a command from inverter control unit 40b of controller 40, and drives it to brushless DC motor 4 Output as power.
  • the number of rotations of the brushless DC motor 4 changes in accordance with the frequency (referred to as output frequency) of the output voltage of the inverter 3.
  • a current sensor 5 for detecting a current flowing through the brushless DC motor 4 is disposed for each phase of the current passage between the inverter 3 and the brushless DC motor 4.
  • the anode of a photodiode (light emitting diode) 23a which is a light emitting element of the photocoupler 23 is connected to the L phase of the AC power supply 1 via a diode 21 for half wave rectification and a resistor 22 for power consumption reduction in series.
  • the cathode of the photodiode 23 a is connected to the N phase of the AC power supply 1. That is, this photocoupler 23 is a so-called photodiode coupler.
  • the diode 21 is for protection against applying an excessive reverse voltage to the photodiode 23a, and applies a positive half wave of the AC power supply voltage Vc to the photodiode 23a.
  • the photocoupler 23 has a CTR (Current Transfer Ratio: also referred to as current transfer ratio or conversion efficiency) of, for example, 100% to 300%.
  • a resistor 25b is connected to the positive side terminal 24a via a resistor 25a, and the other end of the resistor 25b is The negative terminal 24b is connected between the collector and the emitter of the NPN transistor 26 which is a semiconductor switch.
  • the resistor 25 a is, for example, 0 ⁇
  • the resistor 25 b is, for example, 1 k ⁇ .
  • the base of the transistor 26 is connected to one end of the resistor 25 b via the collector and the emitter of the phototransistor 23 b which is a light receiving element of the photocoupler 23.
  • a voltage generated in a series circuit of the resistor 25 b and the collector-emitter of the transistor 26 is applied between the base-emitter of the transistor 26 via the collector-emitter of the phototransistor 23 b of the photocoupler 23.
  • the transistor 26 is turned on in response to the rise from the zero level of the base-emitter voltage Va which is the output voltage of the phototransistor 23 b of the photocoupler 23 and is turned off in response to the fall of the base-emitter voltage Va.
  • the voltage Vb between the collector of the transistor 26 and the negative terminal 24 b is input to the operation unit 29 through a noise filter composed of the resistor 27 and the capacitor 28.
  • the voltage Va between the base and the emitter is referred to as the output voltage Va of the photocoupler 23, and the voltage Vb between the collector of the transistor 26 and the negative terminal 24b is referred to as the input voltage Vb to the operation unit 29.
  • the photocoupler 23 has a rapid rise of the output voltage Va when the current flows through the photodiode 23a and the phototransistor 23b operates (turns on), but the conduction to the photodiode 23a stops and the phototransistor 23b turns off. There is a characteristic that the fall of the output voltage Va is slow.
  • Arithmetic unit 29 sequentially detects the rising point of the positive half wave of AC power supply voltage Vc from the change in state (turn on) of transistor 26 based on the output of photocoupler 23, and the time interval between the detected plural rising points. Is detected as the cycle T of the AC power supply voltage Vc as a so-called power supply cycle T, and the zero cross point of the AC power supply voltage Vc in the period after the detected rising point is estimated based on the detected power supply cycle T.
  • a detection unit 29a, a second detection unit 29b, a first estimation unit 29c, and a second estimation unit 29d are included, and a memory 30 is attached and provided.
  • the operation unit 29 can be configured by a microcomputer, and the first detection unit 29a, the second detection unit 29b, the first estimation unit 29c, and the second estimation unit 29d perform their functions by program processing incorporated in the microcomputer. Can be achieved.
  • the rising point of the positive half wave of the AC power supply voltage Vc is the time when the AC power supply voltage Vc starts to change from the zero level toward the positive peak level.
  • the first detection unit 29a captures the change in state (turn-on) of the transistor 26 based on the output of the photocoupler 23 from the input voltage Vb during the operation of the inverter 3, and detects the change in the captured state.
  • the rising points from the zero level are sequentially detected.
  • the second detection unit 29b sequentially sets, as a power supply cycle T, a period between the rising point t2 detected last among the rising points detected by the first detection unit 29a and the rising point t1 detected one before the last. To detect. Rising points t1 and t2 mean time.
  • the second detection unit 29b includes a timer (clocking means) for measuring a period (time) between the rising point t2 and the rising point t1.
  • the controller 50 is notified of the estimated zero cross point Pd.
  • the falling of the positive half wave of the AC power supply voltage Vc means that the AC power supply voltage Vc changes from the positive peak level toward the zero level.
  • the falling zero cross point Pd of the positive half wave of the AC power supply voltage Vc is a point when the AC power supply voltage Vc changes from the positive peak level toward the zero level and crosses the zero level.
  • the rising of the positive half wave of the AC power supply voltage Vc is a state in which the AC power supply voltage Vc changes from the zero level toward the positive peak level.
  • the rising zero cross point Pu of the positive half wave of the AC power supply voltage Vc is the time when the AC power supply voltage Vc changes from the negative level to the positive level and crosses the zero level.
  • the first estimation unit 29c uses the variation of the value of the AC power supply voltage Vc, the variation of CTR of the photocoupler 23, the ambient temperature variation of the photocoupler 23, etc. Not only adding 1/2 of the power supply period T but also adding a correction value "-.DELTA.t" corresponding to the response delay to the last detected rising point t2 in consideration of the response delay of the photocoupler 23 .
  • the correction value “ ⁇ t” is a fixed value obtained by the following experiment using at least one of the value of the AC power supply voltage Vc, the CTR of the photocoupler 23 and the ambient temperature of the photocoupler 23 as a parameter. It is stored in advance.
  • the fluctuation range of the value of the AC power supply voltage Vc is 170 V to 276 V
  • the fluctuation range of the CTR of the photocoupler 23 is 100% to 300%
  • the fluctuation range of the ambient temperature of the photocoupler 23 is -30 ° C to + 80 ° C.
  • the value of AC power supply voltage Vc is set to the lower limit value "170 V” of fluctuation range
  • the CTR of photocoupler 23 is set to the lower limit value "100%” of fluctuation range
  • the ambient temperature of photocoupler 23 is changed range
  • the lower limit value of “ ⁇ 30 ° C.” is set, and in this state, the turn on of the transistor 26 based on the on output of the phototransistor 23 b of the photocoupler 23 is detected as the rising point tx of the positive half wave of the AC power supply voltage Vc.
  • the value of AC power supply voltage Vc is set to the upper limit value "276 V” of fluctuation range
  • the CTR of photo coupler 23 is set to the upper limit value "300%” of fluctuation range
  • the ambient temperature of photo coupler 23 is the upper limit value.
  • the turn-on of the transistor 26 based on the on output of the phototransistor 23b of the photocoupler 23 is detected as the rising point ty of the positive half wave of the AC power supply voltage Vc1.
  • a difference occurs in the rise time of the AC power supply voltage Vc.
  • the power supply frequency is high, the time required for the AC power supply voltage Vc to reach the voltage at which the photocoupler is lit from the zero cross point is shorter than when the power supply frequency is low. Therefore, taking into consideration that there is an area with a power supply frequency of 50 Hz and an area with a power supply frequency of 60 Hz, a correction value “ ⁇ ta” obtained by adding a correction for the power supply frequency of 50 Hz to the correction value ⁇ t
  • the correction value "-.DELTA.tb" to which the correction of the above is added is obtained in advance and stored in the memory 30.
  • the correction value “ ⁇ t” was obtained using three parameters of the value of the AC power supply voltage Vc, the CTR of the photocoupler 23, and the ambient temperature of the photocoupler 23. Any one of these three parameters The correction value “ ⁇ t” may be determined using only one or two parameters.
  • the diode 21, the resistor 22, the photocoupler 23, the positive terminal 24a, the negative terminal 24b, the resistors 25a and 25b, the transistor 26, the resistor 27, the capacitor 8, the computing unit 29, and the memory 30 make the zero cross detection device 20 Is configured.
  • the controller 40 includes a short circuit control unit 40 a that controls the converter 2 and an inverter control unit 40 b that controls the inverter 3.
  • the short circuit control unit 40a controls the operation timing of the IGBT 12t of the converter 2 using the zero crossing points Pd and Pu estimated by the zero crossing detection device 20 for the improvement of the power factor and the suppression of the harmonic current.
  • the on / off switching of the IGBT 12t of the short circuit 12 is performed in a predetermined period with reference to Pd and Pu, for example, a phase 0 ° to 60 ° and / or a specific timing within a phase 120 ° to 180 °. Since the harmonics increase as the number of on / off switching increases, it is desirable that the number of on / off switching is about 1 to 5 times.
  • a short circuit via the reactor 11 to the AC power supply 1 is intermittently formed by the on / off switching. Along with this, the input current from the AC power supply 1 to the converter 2 becomes a sine wave without distortion. This improves the power factor.
  • the inverter control unit 40b estimates the rotational speed of the brushless DC motor 4 from the detected current of the current sensor 5, and switches the inverter 4 at a timing based on the detected current of the current sensor 5 such that the estimated rotational speed becomes the target rotational speed. So as to change the output frequency of the inverter 4 and execute so-called sensorless vector control.
  • the converter 2, the inverter 3, the current sensor 5, the zero cross detection device 20, and the controller 40 constitute a power conversion device that outputs drive power to the brushless DC motor 4.
  • the photodiode 23a of the photocoupler 23 emits light in response to the rise, and the phototransistor 23b receiving the light is turned on.
  • the transistor 26 is turned on in response to the rise. Then, in response to the turning on of the transistor 26, the input voltage Vb to the operation unit 29 changes from the high level "H" to the low level "L".
  • operation unit 29 sets count value n for cycle specification, rising point t1 in memory 30, and flag f for process confirmation to "0". Clear (S2). Then, the operation unit 29 starts time counting t (S3) and monitors the change of the input voltage Vb from high level "H” to low level “L” (S4).
  • the calculation unit 29 confirms the flag f (S5). Since the flag f at this time is "0" (NO in S5), the calculation unit 29 returns to the monitoring of S4.
  • the operation unit 29 increments the count value n by “1” to “1”.
  • the time count t at this time is detected as the rising point (rising timing) t2 of the first (first) positive half wave Vc1 of the AC power supply voltage Vc.
  • the power supply cycle or cycle means the time required for one cycle of the power supply voltage.
  • the calculation unit 29 determines whether or not the detected power supply cycle T1 falls under the appropriate condition (Ta ⁇ T1 ⁇ Tc) such that the detected power supply cycle T1 is not less than the cycle Ta corresponding to the lower limit frequency 45 Hz and less than the cycle Tc corresponding to the upper limit frequency 66 Hz. It judges (S9).
  • the power supply cycle T1 detected at the rise of the first positive half wave Vc1 immediately after the start of the operation of the inverter 3 may be small and may not satisfy the appropriate condition. If the power supply cycle T1 does not satisfy the appropriate condition (NO in S9), the calculation unit 29 clears the power supply cycle T1 to "0" (S10). Then, the operation unit 29 updates and holds the rising point t2 detected this time as the rising point t1 in the memory 30 (S16). Subsequently, when the operation of the inverter 3 is not stopped (NO in S17), the operation unit 29 returns to S4 and monitors the change of the input voltage Vb from high level "H" to low level "L".
  • the calculation unit 29 confirms the flag f (S5). Since the flag f at this time is still "0" (NO in S5), the calculation unit 29 returns to the monitoring of S4.
  • the calculation unit 29 determines whether the detected power supply cycle T2 satisfies the appropriate condition (Ta ⁇ T2 ⁇ Tc) (S9). If the power supply cycle T2 satisfies the appropriate condition (YES in S9), the calculation unit 29 compares the power supply cycle T2 with the cycle Tb corresponding to the reference frequency 55 Hz (S11). If the power supply cycle T2 is less than or equal to the cycle Tb (T2 ⁇ Tb; YES in S11), the calculation unit 29 determines that the power supply frequency is 50 Hz and sets 1 / l of the power supply cycle T2 to the rising point t2 detected this time.
  • the calculation unit 29 notifies the short circuit control unit 40a of the controller 40 of the estimated zero crossing point Pd (S14). Subsequently, the operation unit 29 sets the flag f to "1" (S15), and updates and holds the rising point t2 in the memory 30 as the rising point t1 in the memory 30 (S16). If the operation of inverter 3 is not stopped (NO at S17), operation unit 29 returns to S4 to monitor the change of input voltage Vb from high level "H" to low level "L".
  • the correction value "-.DELTA.tz” is either one of the correction value "-.DELTA.ta” for 50 Hz or the correction value "-.DELTA.tb” for 60 Hz used according to the comparison result of S11.
  • operation unit 29 notifies the estimated zero crossing point Pu to the short circuit control unit 40a of the controller 40 (S19), and clears the flag f to "0" (S20). Subsequently, if the operation of inverter 3 is not stopped (NO at S17), operation unit 29 returns to S4 and monitors the change of input voltage Vb from high level "H” to low level “L”. .
  • the calculation unit 29 determines whether the detected power supply cycle T3 satisfies the appropriate condition (Ta ⁇ T3 ⁇ Tc) (S9). If the power supply cycle T3 satisfies the appropriate condition (YES in S9), the calculation unit 29 compares the power supply cycle T3 with the cycle Tb corresponding to the reference frequency 55 Hz (S11). If the power supply cycle T3 is equal to or less than the cycle Tb (T3 ⁇ Tb; YES in S11), the calculation unit 29 determines that the power supply frequency is 50 Hz, the power supply cycle detected immediately before the rising point t2 detected this time.
  • the calculation unit 29 determines that the power supply frequency is 60 Hz, and holds 1 to 1 of the power supply cycle T3 at the rising point t2 held this time.
  • the point (t2 + T3 / 2- ⁇ tb) at which the value of / 2 and the correction value "- ⁇ tb" for 60 Hz are added is estimated as the zero-crossing point Pd of the falling edge of the third half wave (the next time) S13).
  • the calculation unit 29 notifies the short circuit control unit 40a of the controller 40 of the estimated zero crossing point Pd (S14). Subsequently, the operation unit 29 sets the flag f to "1" (S15), and updates and holds the rising point t2 in the memory 30 as the rising point t1 in the memory 30 (S16). If the operation of inverter 3 is not stopped (NO at S17), operation unit 29 returns to S4 to monitor the change of input voltage Vb from high level "H" to low level "L".
  • operation unit 29 notifies the estimated zero crossing point Pu to the short circuit control unit 40a of the controller 40 (S19), and clears the flag f to "0" (S20). Subsequently, if the operation of inverter 3 is not stopped (NO at S17), operation unit 29 returns to S4 and monitors the change of input voltage Vb from high level "H” to low level “L”. .
  • the falling zero cross point Pd of the third positive half wave Vc3 and the rising zero cross point Pu of the fourth positive half wave Vc4 are estimated. I will not.
  • the next power supply cycle T4 is detected based on the rising point t2 of the fourth positive half wave Vc4 to be detected next, and the fourth positive half wave Vc4 is detected based on the power supply cycle T4. And the rising zero cross point Pu of the fifth (next) positive side half wave Vc5 are estimated.
  • the photocoupler 23 has a rapid rise of the output voltage Va when the current flows through the photodiode 23a and the phototransistor 23b is turned on, but the output voltage Va when the conduction to the photodiode 23a is stopped and the phototransistor 23b is turned off. Fall is slow. For this reason, as in the prior art, when on and off of the photocoupler 23 are detected as the zero cross point of the AC power supply voltage Vc, an error occurs in detection.
  • a light emitting element emitting light by a half wave of an AC power supply voltage and a photo coupler having a light receiving element turned on in response to the light emission of the light emitting element
  • the rising point of the wave is detected, the time interval between the detected rising points is detected as the period of the AC power supply voltage, and the zero crossing point of the AC power supply voltage in the period after the detected rising point is detected
  • an operation unit that estimates based on the above. Therefore, in consideration of the characteristics of photocoupler 23, the rising point of the positive half wave corresponding to the rising of output voltage Va is sequentially detected through photocoupler 23, and power supply cycle T is detected from each detected rising point.
  • the zero cross points Pd and Pu of the AC power supply voltage Vc are You can catch it properly.
  • the rising points of the positive half wave are sequentially detected, the actual power supply cycle T is detected from each detected rising point, and the next and the next time on the basis of the detected power supply cycle T. Since the zero crossing points Pd and Pu are estimated, the zero crossing points Pd and Pu can be accurately estimated regardless of the local power supply situation.
  • the correction value “ ⁇ t” is added to the estimation of the zero cross points Pd and Pu, a photocoupler that takes fluctuation of the value of the AC power supply voltage Vc, fluctuation of CTR of the photocoupler 23, ambient temperature fluctuation of the photocoupler 23, etc. The influence on the response delay of 23 can be mitigated, and also at this point, the zero crossing points Pd and Pu can be accurately estimated. Further, since the correction values “ ⁇ ta” and “ ⁇ tb” based on the power supply frequency are added to the estimation of the zero crossing points Pd and Pu, the zero crossing points Pd and Pu can be estimated more accurately.
  • the rising point of the positive half wave of the AC power supply voltage Vc is detected by the photocoupler 23, but the polarity of the diode 21 and the polarity of the photodiode 23a are respectively connected reversely to the state of FIG.
  • the rising point of the negative half wave of the AC power supply voltage Vc may be detected.
  • the rising of the negative half wave of the AC power supply voltage Vc means that the AC power supply voltage Vc changes from the zero level toward the peak level on the negative side.
  • Arithmetic unit 29 estimates the zero cross point Pu of the rise of the negative half wave of AC power supply voltage Vc and the zero cross point Pd of the fall of the negative half wave of AC power supply voltage Vc.
  • the zero cross point Pu of the rise of the negative half wave of the AC power supply voltage Vc is the time when the AC power supply voltage Vc changes from the positive level to the negative level and crosses the zero level.
  • the falling zero cross point Pd of the negative half wave of the AC power supply voltage Vc is a point when the AC power supply voltage Vc changes from the negative peak level toward the zero level and crosses the zero level.
  • the estimated zero crossing points Pd and Pu are used for on / off switching control to improve the power factor.
  • the estimated zero crossing points Pd and Pu are not limited to the above.
  • power factor improvement and suppression of harmonic current can also be performed by applying to a reference of on / off timing of a switching element of a step-up chopper circuit or a switching element of a step-up chopper circuit or a PWM converter which boosts alternating current of alternating current power.

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  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Inverter Devices (AREA)

Abstract

The present invention detects the rising points of a half wave of an AC power supply voltage from the output of a photocoupler, detects the time interval between a plurality of detected rising points as the period of the AC power supply voltage, and uses the detected period to estimate the zero crossing points (Pd, Pu) of the AC power supply voltage in a period of time after the detected rising points.

Description

ゼロクロス検出装置および電力変換装置Zero-crossing detection device and power converter
　この発明は、交流電源電圧のゼロクロス点を検出するゼロクロス検出装置およびこのゼロクロス検出装置を備えた電力変換装置に関する。 The present invention relates to a zero-crossing detecting device for detecting a zero crossing point of an AC power supply voltage, and a power conversion device provided with the zero-crossing detecting device.
　交流電源を整流するコンバータを備えた電力変換装置では、力率の改善や高調波電流の抑制などのため、交流電源電圧のゼロクロス点を検出し、検出したゼロクロス点を基準としてスイッチング素子のオン,オフ動作タイミングを決定している。たとえば、高力率電源回路では、ゼロクロス点を基準とした所定期間において、交流電源に対する短絡回路をリアクタを通して形成する。 In a power converter provided with a converter that rectifies AC power, the zero cross point of the AC power supply voltage is detected to improve power factor and suppress harmonic current, and the switching element is turned on based on the detected zero cross point, The off operation timing is determined. For example, in a high power factor power supply circuit, a short circuit to an AC power supply is formed through the reactor for a predetermined period based on the zero crossing point.
　このような電力変換装置では、交流電源電圧のゼロクロス点をフォトカプラを用いて検出している。 In such a power converter, the zero cross point of the AC power supply voltage is detected using a photocoupler.
特開昭５８－４６７１８号公報Japanese Patent Application Laid-Open No. 58-46718 特許第４１５７６１９号公報Patent No. 4157619 gazette
　ゼロクロス点の検出に用いるフォトカプラは、発光素子に電流が流れて受光素子がオンするときの出力電圧の立上がりは速いが、発光素子への通電が止まって受光素子がオフするときの出力電圧の立下がりは遅いという特性がある。このフォトカプラのオン，オフを交流電源電圧のゼロクロス点として検出すると、検出に誤差を生じてしまう。この結果、電力変換装置としては、当初目的とした力率の改善および高調波電流の抑制効果が得られなくなる。また、交流電源の正負の双方のゼロクロスを検出する場合、フォトカプラにはゼロクロス近辺を除く期間で常に電流が流れ、電力ロスにつながる。 The photocoupler used to detect the zero cross point has a rapid rise in output voltage when a current flows through the light emitting element and the light receiving element is turned on, but the output voltage when the light emitting element is turned off and the light receiving element is turned off There is a characteristic that falling is slow. If the on / off state of the photocoupler is detected as the zero cross point of the AC power supply voltage, an error occurs in the detection. As a result, the power converter can not obtain the originally intended power factor improvement and harmonic current suppression effects. In addition, when both positive and negative zero crossings of the AC power supply are detected, a current always flows through the photocoupler in a period excluding the vicinity of the zero crossing, which leads to power loss.
　本発明の実施形態のゼロクロス検出装置は、交流電源電圧のゼロクロス点を効率的に誤差なく的確に捕えることを目的とする。 An object of the zero-crossing detecting device according to the embodiment of the present invention is to capture the zero-crossing point of the AC power supply voltage efficiently and accurately without error.
　請求項１のゼロクロス検出装置は、フォトカプラおよび演算部を備える。フォトカプラは、交流電源電圧の半波により発光する発光素子およびこの発光素子の発光を受けてオンする受光素子を有する。演算部は、前記フォトカプラの出力から前記交流電源電圧の半波の立上がり点を逐次に検出し、検出した立上がり点のうち最後に検出した立上がり点と最後より１つ前に検出した立上がり点との時間間隔を前記交流電源電圧の周期として検出し、前記最後に検出した立上がり点に前記検出した周期の1/2の値を加えた時点を、前記最後に検出した立上がり点の後の前記交流電源電圧の最初の半波のゼロクロス点として推定し、前記最後に検出した立上がり点に前記検出した周期を加えた時点を、前記最初の半波の次の半波のゼロクロス点として推定する。 The zero-crossing detection apparatus according to claim 1 includes a photocoupler and an operation unit. The photocoupler has a light emitting element which emits light by a half wave of an AC power supply voltage and a light receiving element which is turned on in response to the light emission of the light emitting element. The operation unit sequentially detects the rising point of the half wave of the AC power supply voltage from the output of the photocoupler, and among the detected rising points, the rising point detected last and the rising point detected one before the last Time interval is detected as the cycle of the alternating current power supply voltage, and the time point when the half of the detected cycle is added to the last detected rising point is the alternating current after the last detected rising point The point at which the zero crossing point of the first half wave of the power supply voltage is estimated, and the point at which the detected period is added to the last detected rising point is estimated as the zero crossing point of the next half wave of the first half wave.
図１は一実施形態の構成を示すブロック図である。FIG. 1 is a block diagram showing the configuration of one embodiment. 図２は一実施形態における交流電源電圧の波形、フォトカプラの出力電圧の波形、および演算部への入力電圧の波形を示す図である。FIG. 2 is a diagram showing a waveform of an AC power supply voltage, a waveform of an output voltage of a photocoupler, and a waveform of an input voltage to a computing unit in one embodiment. 図３は一実施形態における演算部の処理を示すフローチャートである。FIG. 3 is a flowchart showing processing of the computing unit in one embodiment.
　以下、本発明の一実施形態について図面を参照して説明する。　
　図１に示すように、交流電源１のＬ相とＮ相にコンバータ２の入力端が接続され、そのコンバータ２の出力端にインバータ３の入力端が接続されている。そして、インバータ３の出力端に圧縮機駆動用のブラシレスＤＣモータ４が接続されている。 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the input end of the converter 2 is connected to the L phase and the N phase of the AC power supply 1, and the input end of the inverter 3 is connected to the output end of the converter 2. The output terminal of the inverter 3 is connected to a brushless DC motor 4 for driving a compressor.
　コンバータ２は、交流電源１のＬ相につながる電源ラインに配置されたリアクタ１１、このリアクタ１１を介して交流電源１のＬ相とＮ相との間に接続された短絡回路１２、上記リアクタ１１を介して交流電源１のＬ相とＮ相との間に接続された全波整流回路１３、この全波整流回路１３の出力端に接続された平滑コンデンサ１４を含み、交流電源１の電圧（交流電源電圧という）Ｖcを直流電圧に変換する。短絡回路１２は、４つのダイオード１２a～１２dのブリッジ回路および１つのスイッチング素子たとえばＩＧＢＴ（Insulated Gate Bipolar Transistor）１２tを有する。交流電源電圧Ｖcの正レベル期間においてＩＧＢＴ１２tがオンすると、交流電源１のＬ相からリアクタ１１，ダイオード１２c，ＩＧＢＴ１２t，ダイオード１２bを通って交流電源１のＮ相に通じる短絡路が形成される。交流電源電圧Ｖｃの負レベル期間においてＩＧＢＴ１２tがオンすると、交流電源１のＮ相からダイオード１２d，ＩＧＢＴ１２t，ダイオード１２a，リアクタ１１を通って交流電源１のＬ相に通じる短絡路が形成される。ＩＧＢＴ１２tは、コントローラ４０の短絡制御部４０aによりオン，オフ制御される。 Converter 2 includes a reactor 11 disposed in a power supply line connected to L phase of AC power supply 1, a short circuit 12 connected between L phase and N phase of AC power supply 1 via reactor 11, and the above reactor 11. Includes a full wave rectifier circuit 13 connected between the L phase and the N phase of the AC power supply 1 via the output terminal of the full wave rectifier circuit 13 and a smoothing capacitor 14 connected to the output terminal of the full wave Convert the AC power supply voltage Vc into a DC voltage. The short circuit 12 includes a bridge circuit of four diodes 12a to 12d and one switching element such as an IGBT (Insulated Gate Bipolar Transistor) 12t. When the IGBT 12t is turned on during the positive level period of the AC power supply voltage Vc, a short circuit leading to the N phase of the AC power supply 1 is formed from the L phase of the AC power supply 1 through the reactor 11, the diode 12c, the IGBT 12t, and the diode 12b. When the IGBT 12t is turned on in a negative level period of the AC power supply voltage Vc, a short circuit from the N phase of the AC power supply 1 through the diode 12d, the IGBT 12t, the diode 12a, and the reactor 11 is formed. The IGBT 12 t is on / off controlled by the short circuit control unit 40 a of the controller 40.
　インバータ３は、コンバータ２の出力電圧（平滑コンデンサ１４の電圧）をコントローラ４０のインバータ制御部４０ｂからの指令に応じたスイッチングにより所定周波数の交流電圧に変換し、それをブラシレスＤＣモータ４への駆動電力として出力する。このインバータ３の出力電圧の周波数（出力周波数という）に応じてブラシレスＤＣモータ４の回転数が変化する。インバータ３とブラシレスＤＣモータ4との間の各相の通電路毎に、ブラシレスＤＣモータ４に流れる電流を検知する電流センサ５が配置されている。 Inverter 3 converts the output voltage of converter 2 (voltage of smoothing capacitor 14) into AC voltage of a predetermined frequency by switching according to a command from inverter control unit 40b of controller 40, and drives it to brushless DC motor 4 Output as power. The number of rotations of the brushless DC motor 4 changes in accordance with the frequency (referred to as output frequency) of the output voltage of the inverter 3. A current sensor 5 for detecting a current flowing through the brushless DC motor 4 is disposed for each phase of the current passage between the inverter 3 and the brushless DC motor 4.
　一方、交流電源１のＬ相に半波整流用のダイオード２１および消費電力低減用の抵抗器２２を直列に介してフォトカプラ２３の発光素子であるフォトダイオード（発光ダイオード）２３aのアノードが接続され、そのフォトダイオード２３aのカソードが交流電源１のＮ相に接続されている。すなわち、このフォトカプラ２３は、いわゆるフォトダイオードカプラである。ダイオード２１は、フォトダイオード２３aへ過大な逆電圧が印加されないようにする保護用であり、交流電源電圧Ｖｃの正側半波をフォトダイオード２３aに印加する。フォトカプラ２３は、CTR（Current Transfer Ratio：電流伝達率または変換効率ともいう）が例えば100%～300%である。 On the other hand, the anode of a photodiode (light emitting diode) 23a which is a light emitting element of the photocoupler 23 is connected to the L phase of the AC power supply 1 via a diode 21 for half wave rectification and a resistor 22 for power consumption reduction in series. The cathode of the photodiode 23 a is connected to the N phase of the AC power supply 1. That is, this photocoupler 23 is a so-called photodiode coupler. The diode 21 is for protection against applying an excessive reverse voltage to the photodiode 23a, and applies a positive half wave of the AC power supply voltage Vc to the photodiode 23a. The photocoupler 23 has a CTR (Current Transfer Ratio: also referred to as current transfer ratio or conversion efficiency) of, for example, 100% to 300%.
　直流定電圧（5V）が印加される正側端子２４aおよび負側端子２４bのうち、正側端子２４aに抵抗器２５aを介して抵抗器２５bの一端が接続され、その抵抗器２５bの他端が半導体スイッチであるＮＰＮ型トランジスタ２６のコレクタ・エミッタ間を介して負側端子２４bに接続されている。抵抗器２５aは例えば0Ω、抵抗器２５bは例えば1kΩである。トランジスタ２６のベースは、フォトカプラ２３の受光素子であるフォトトランジスタ２３bのコレクタ・エミッタ間を介して抵抗器２５bの一端に接続されている。すなわち、抵抗器２５bとトランジスタ２６のコレクタ・エミッタ間との直列回路に生じる電圧が、フォトカプラ２３のフォトトランジスタ２３bのコレクタ・エミッタ間を介してトランジスタ２６のベース・エミッタ間に印加される。 Of the positive side terminal 24a and the negative side terminal 24b to which a constant DC voltage (5 V) is applied, one end of a resistor 25b is connected to the positive side terminal 24a via a resistor 25a, and the other end of the resistor 25b is The negative terminal 24b is connected between the collector and the emitter of the NPN transistor 26 which is a semiconductor switch. The resistor 25 a is, for example, 0Ω, and the resistor 25 b is, for example, 1 kΩ. The base of the transistor 26 is connected to one end of the resistor 25 b via the collector and the emitter of the phototransistor 23 b which is a light receiving element of the photocoupler 23. That is, a voltage generated in a series circuit of the resistor 25 b and the collector-emitter of the transistor 26 is applied between the base-emitter of the transistor 26 via the collector-emitter of the phototransistor 23 b of the photocoupler 23.
　トランジスタ２６は、フォトカプラ２３のフォトトランジスタ２３bの出力電圧であるベース・エミッタ間電圧Ｖaのゼロレベルからの立上がりに応じてターンオンし、そのベース・エミッタ間電圧Ｖaの立下がりに応じてターンオフする。とくに、トランジスタ２６は、小さいベース・エミッタ間電圧Ｖaでもターンオンする特性を有する例えば入力抵抗r1=2.2kΩおよびベース・エミッタ間抵抗r2=47kΩの製品名“RN1405”という素子であり、ベース・エミッタ間電圧Ｖaの立上がりに対する応答性が速い。このトランジスタ２６のコレクタと負側端子２４bとの間の電圧Ｖbが、抵抗器２７およびコンデンサ２８からなるノイズフィルタを介して、演算部２９に入力される。 The transistor 26 is turned on in response to the rise from the zero level of the base-emitter voltage Va which is the output voltage of the phototransistor 23 b of the photocoupler 23 and is turned off in response to the fall of the base-emitter voltage Va. In particular, the transistor 26 is an element with a product name “RN1405” having an input resistance r1 = 2.2 kΩ and a base-emitter resistance r2 = 47 kΩ, for example, having characteristics of turning on even with a small base-emitter voltage Va. Responsiveness to the rise of voltage Va is fast. The voltage Vb between the collector of the transistor 26 and the negative terminal 24 b is input to the operation unit 29 through a noise filter composed of the resistor 27 and the capacitor 28.
　以下、ベース・エミッタ間電圧Ｖaのことをフォトカプラ２３の出力電圧Ｖaと称し、トランジスタ２６のコレクタと負側端子２４bとの間の電圧Ｖbのことを演算部２９への入力電圧Ｖbと称する。 Hereinafter, the voltage Va between the base and the emitter is referred to as the output voltage Va of the photocoupler 23, and the voltage Vb between the collector of the transistor 26 and the negative terminal 24b is referred to as the input voltage Vb to the operation unit 29.
　フォトカプラ２３は、フォトダイオード２３aに電流が流れてフォトトランジスタ２３bが動作（オン）するときの出力電圧Ｖaの立上がりは速いが、フォトダイオード２３aへの通電が止まってフォトトランジスタ２３bがオフするときの出力電圧Ｖaの立下がりは遅いという特性がある。 The photocoupler 23 has a rapid rise of the output voltage Va when the current flows through the photodiode 23a and the phototransistor 23b operates (turns on), but the conduction to the photodiode 23a stops and the phototransistor 23b turns off. There is a characteristic that the fall of the output voltage Va is slow.
　演算部２９は、フォトカプラ２３の出力に基づくトランジスタ２６の状態変化（ターンオン）から交流電源電圧Ｖcの正側半波の立上がり点を逐次に検出し、検出した複数の立上がり点の相互の時間間隔を交流電源電圧Ｖcの周期Ｔいわゆる電源周期Ｔとして検出し、上記検出した立上がり点より後の期間における交流電源電圧Ｖcのゼロクロス点を上記検出した電源周期Ｔに基づいて推定するもので、第１検出部２９a，第２検出部２９b，第１推定部２９c，第２推定部２９dを含むとともに、メモリ３０を付属して備える。演算部２９はマイクロコンピュータで構成することができ、第１検出部２９a，第２検出部２９b，第１推定部２９c，第２推定部２９dはそのマイクロコンピュータに組み込まれたプログラム処理によってその機能を達成することができる。なお、交流電源電圧Ｖcの正側半波の立上がり点とは、交流電源電圧Ｖcがゼロレベルから正側のピークレベルに向かい変化を始める時点のことである。 Arithmetic unit 29 sequentially detects the rising point of the positive half wave of AC power supply voltage Vc from the change in state (turn on) of transistor 26 based on the output of photocoupler 23, and the time interval between the detected plural rising points. Is detected as the cycle T of the AC power supply voltage Vc as a so-called power supply cycle T, and the zero cross point of the AC power supply voltage Vc in the period after the detected rising point is estimated based on the detected power supply cycle T. A detection unit 29a, a second detection unit 29b, a first estimation unit 29c, and a second estimation unit 29d are included, and a memory 30 is attached and provided. The operation unit 29 can be configured by a microcomputer, and the first detection unit 29a, the second detection unit 29b, the first estimation unit 29c, and the second estimation unit 29d perform their functions by program processing incorporated in the microcomputer. Can be achieved. The rising point of the positive half wave of the AC power supply voltage Vc is the time when the AC power supply voltage Vc starts to change from the zero level toward the positive peak level.
　第１検出部２９aは、インバータ３の運転時、フォトカプラ２３の出力に基づくトランジスタ２６の状態変化（ターンオン）を入力電圧Ｖbから捕え、捕えた状態変化から交流電源電圧Ｖcの正側半波のゼロレベルからの立上がり点を逐次に検出する。第２検出部２９bは、第１検出部２９aが検出した複数の立上がり点のうち最後に検出した立上がり点ｔ2と最後より１つ前に検出した立上がり点ｔ1との期間を電源周期Ｔとして逐次に検出する。立上がり点ｔ１，ｔ２は、時間を意味する。なお、第２検出部２９bは、立上がり点ｔ2と立上がり点ｔ1との間の期間（時間）を計測するためのタイマー（計時手段）を備える。 The first detection unit 29a captures the change in state (turn-on) of the transistor 26 based on the output of the photocoupler 23 from the input voltage Vb during the operation of the inverter 3, and detects the change in the captured state. The rising points from the zero level are sequentially detected. The second detection unit 29b sequentially sets, as a power supply cycle T, a period between the rising point t2 detected last among the rising points detected by the first detection unit 29a and the rising point t1 detected one before the last. To detect. Rising points t1 and t2 mean time. The second detection unit 29b includes a timer (clocking means) for measuring a period (time) between the rising point t2 and the rising point t1.
　第１推定部２９cは、上記最後に検出した立上がり点ｔ2に上記検出した電源周期Ｔの1/2の値を加えた時点（=t2＋T/2）を、上記最後に検出した立上がり点ｔ2の後の期間における交流電源電圧Ｖcの最初(次)の正側半波の立下がりのゼロクロス点Ｐdとして推定し、推定したゼロクロス点Ｐdをコントローラ４０に通知する。交流電源電圧Ｖcの正側半波の立下がりとは、交流電源電圧Ｖcが正側のピークレベルからゼロレベルに向かって変化していく様子のことである。交流電源電圧Ｖcの正側半波の立下がりのゼロクロス点Ｐdとは、交流電源電圧Ｖcが正側のピークレベルからゼロレベルに向かい変化してゼロレベルを横切る時点のことである。 The first estimation unit 29c adds a point (= t2 + T / 2) at which the value of 1⁄2 of the detected power supply cycle T is added to the last detected rising point t2 after the last detected rising point t2. Of the first (next) positive side half wave of the AC power supply voltage Vc in the period of 1, and the controller 50 is notified of the estimated zero cross point Pd. The falling of the positive half wave of the AC power supply voltage Vc means that the AC power supply voltage Vc changes from the positive peak level toward the zero level. The falling zero cross point Pd of the positive half wave of the AC power supply voltage Vc is a point when the AC power supply voltage Vc changes from the positive peak level toward the zero level and crosses the zero level.
　第２推定部２９dは、上記最後に検出した立上がり点ｔ2に上記検出した電源周期Ｔを加えた時点（=t2＋T）を、上記最後に検出した立上がり点ｔ2の後の期間における交流電源電圧Ｖcの上記最初(次)の次の正側半波の立上がりのゼロクロス点Ｐuとして推定し、推定したゼロクロス点Ｐuをコントローラ４０に通知する。交流電源電圧Ｖcの正側半波の立上がりとは、交流電源電圧Ｖcがゼロレベルから正側のピークレベルに向かい変化していく様子のことである。交流電源電圧Ｖcの正側半波の立上がりのゼロクロス点Ｐuとは、交流電源電圧Ｖcが負側レベルから正側レベルに向かい変化してゼロレベルを横切る時点のことである。 The second estimation unit 29d adds the detected power supply cycle T to the last detected rising point t2 (= t2 + T) at the time of the AC power supply voltage Vc in the period after the last detected rising point t2. It estimates as a zero crossing point Pu of the rise of the first (next) following positive side half wave, and notifies the controller 40 of the estimated zero crossing point Pu. The rising of the positive half wave of the AC power supply voltage Vc is a state in which the AC power supply voltage Vc changes from the zero level toward the positive peak level. The rising zero cross point Pu of the positive half wave of the AC power supply voltage Vc is the time when the AC power supply voltage Vc changes from the negative level to the positive level and crosses the zero level.
　さらに、第１推定部２９cは、ゼロクロス点Ｐｄ，Ｐｕの推定精度を上げるために、交流電源電圧Ｖcの値の変動、フォトカプラ２３のCTRの変動、フォトカプラ２３の周囲温度変動などを要因とするフォトカプラ２３の応答遅れを考慮して、上記最後に検出した立上がり点ｔ2に、電源周期Ｔの1/2の値を加えるだけでなく、応答遅れに相当する補正値“－Δｔ”も加える。こうして求めた時点（=t2＋T/2－Δt）を、第１推定部２９ｃは、上記最後に検出した立上がり点ｔ2の後の期間における交流電源電圧Ｖcの最初(次)の正側半波の立下がりのゼロクロス点Ｐdとして推定する。 Furthermore, in order to increase the estimation accuracy of the zero-crossing points Pd and Pu, the first estimation unit 29c uses the variation of the value of the AC power supply voltage Vc, the variation of CTR of the photocoupler 23, the ambient temperature variation of the photocoupler 23, etc. Not only adding 1/2 of the power supply period T but also adding a correction value "-.DELTA.t" corresponding to the response delay to the last detected rising point t2 in consideration of the response delay of the photocoupler 23 . The first estimation unit 29c determines the time (= t2 + T / 2−Δt) obtained in this way, by the first (next) positive half wave of the AC power supply voltage Vc in the period after the last detected rising point t2. Estimated as a falling zero crossing point Pd.
　補正値“－Δｔ”は、交流電源電圧Ｖcの値、フォトカプラ２３のCTR、フォトカプラ２３の周囲温度の少なくとも１つをパラメータとして用いる下記の実験により求めた固定の値であり、メモリ３０に予め記憶されている。 The correction value “−Δt” is a fixed value obtained by the following experiment using at least one of the value of the AC power supply voltage Vc, the CTR of the photocoupler 23 and the ambient temperature of the photocoupler 23 as a parameter. It is stored in advance.
　例えば、交流電源電圧Ｖcの値の変動幅が170V～276V、フォトカプラ２３のCTRの変動幅が100%～300%、フォトカプラ２３の周囲温度の変動幅が-30℃～+80℃であると仮定する。この場合、交流電源電圧Ｖcの値を変動幅の下限値“170V”に設定し、フォトカプラ２３のCTRを変動幅の下限値“100%”に設定し、フォトカプラ２３の周囲温度を変動幅の下限値“-30℃”に設定し、この状態で、フォトカプラ２３のフォトトランジスタ２３bのオン出力に基づくトランジスタ２６のターンオンを交流電源電圧Ｖcの正側半波の立上がり点ｔxとして検出する。次に、交流電源電圧Ｖcの値を変動幅の上限値“276V”に設定し、フォトカプラ２３のCTRを変動幅の上限値“300%”に設定し、フォトカプラ２３の周囲温度を上限値“+80℃”に設定し、この状態で、フォトカプラ２３のフォトトランジスタ２３bのオン出力に基づくトランジスタ２６のターンオンを交流電源電圧Ｖc1の正側半波の立上がり点ｔyとして検出する。そして、検出したゼロクロス点ｔx，ｔyの和の1/2の値[=(tx＋ty)/2]に負の符号を付し、それを補正値“－Δｔ”と定める。 For example, the fluctuation range of the value of the AC power supply voltage Vc is 170 V to 276 V, the fluctuation range of the CTR of the photocoupler 23 is 100% to 300%, and the fluctuation range of the ambient temperature of the photocoupler 23 is -30 ° C to + 80 ° C. Suppose. In this case, the value of AC power supply voltage Vc is set to the lower limit value "170 V" of fluctuation range, the CTR of photocoupler 23 is set to the lower limit value "100%" of fluctuation range, and the ambient temperature of photocoupler 23 is changed range The lower limit value of “−30 ° C.” is set, and in this state, the turn on of the transistor 26 based on the on output of the phototransistor 23 b of the photocoupler 23 is detected as the rising point tx of the positive half wave of the AC power supply voltage Vc. Next, the value of AC power supply voltage Vc is set to the upper limit value "276 V" of fluctuation range, the CTR of photo coupler 23 is set to the upper limit value "300%" of fluctuation range, and the ambient temperature of photo coupler 23 is the upper limit value. In this state, the turn-on of the transistor 26 based on the on output of the phototransistor 23b of the photocoupler 23 is detected as the rising point ty of the positive half wave of the AC power supply voltage Vc1. Then, a negative sign is attached to the value [= (tx + ty) / 2] which is half the sum of the detected zero crossing points tx and ty, and this is defined as a correction value “−Δt”.
　さらに、電源周波数が異なると、交流電源電圧Ｖcの立ち上がり時間に差が生じる。具体的には、電源周波数が高い場合は、低い場合に比して、交流電源電圧Ｖｃがゼロクロス点からフォトカプラが点灯する電圧に達するまでの時間が短くなる。そこで、電源周波数50Hzの地域と電源周波数60Hzの地域があることを考慮し、上記補正値Δｔに電源周波数50Hz用の補正を加えた補正値“－Δｔa”および上記補正値Δｔに電源周波数60Hz用の補正を加えた補正値“－Δｔb”を予め求めて、それをメモリ３０に記憶している。 Furthermore, when the power supply frequency is different, a difference occurs in the rise time of the AC power supply voltage Vc. Specifically, when the power supply frequency is high, the time required for the AC power supply voltage Vc to reach the voltage at which the photocoupler is lit from the zero cross point is shorter than when the power supply frequency is low. Therefore, taking into consideration that there is an area with a power supply frequency of 50 Hz and an area with a power supply frequency of 60 Hz, a correction value “−Δta” obtained by adding a correction for the power supply frequency of 50 Hz to the correction value Δt The correction value "-.DELTA.tb" to which the correction of the above is added is obtained in advance and stored in the memory 30.
　上記実験では、交流電源電圧Ｖcの値、フォトカプラ２３のCTR、フォトカプラ２３の周囲温度の３つのパラメータを用いて補正値“－Δｔ”を求めたが、これら３つのパラメータのうちいずれか１つまたは２つのパラメータのみを用いて補正値“－Δｔ”を求めてもよい。 In the above experiment, the correction value “−Δt” was obtained using three parameters of the value of the AC power supply voltage Vc, the CTR of the photocoupler 23, and the ambient temperature of the photocoupler 23. Any one of these three parameters The correction value “−Δt” may be determined using only one or two parameters.
　上記ダイオード２１、抵抗器２２、フォトカプラ２３、正側端子２４a、負側端子２４b、抵抗器２５a，２５ｂ、トランジスタ２６、抵抗器２７、コンデンサ８、演算部２９、メモリ３０により、ゼロクロス検出装置２０が構成されている。 The diode 21, the resistor 22, the photocoupler 23, the positive terminal 24a, the negative terminal 24b, the resistors 25a and 25b, the transistor 26, the resistor 27, the capacitor 8, the computing unit 29, and the memory 30 make the zero cross detection device 20 Is configured.
　コントローラ４０は、コンバータ２を制御する短絡制御部４０aおよびインバータ３を制御するインバータ制御部４０bを含む。短絡制御部４０aは、力率の改善および高調波電流の抑制のため、ゼロクロス検出装置２０によって推定されたゼロクロス点Ｐd，Ｐuを用いてコンバータ２のＩＧＢＴ１２ｔの動作タイミングを制御するもので、ゼロクロス点Ｐd，Ｐuを基準とする所定期間たとえば位相0°～60°の期間および／または位相120°～180°の期間内の特定のタイミングにおいて、短絡回路１２のＩＧＢＴ１２tのオン，オフスイッチングを行う。なお、オン，オフスイッチングの回数が多くなると高調波が増加するため、オン，オフの回数は１～５回程度が望ましい。このオン，オフスイッチングにより、交流電源１に対するリアクタ１１を介した短絡回路が断続的に形成される。これに伴い、交流電源１からコンバータ２への入力電流が歪のない正弦波となる。これにより、力率が改善される。インバータ制御部４０bは、電流センサ５の検知電流からブラシレスＤＣモータ４の回転速度を推定し、推定した回転速度が目標回転速度となるように電流センサ５の検知電流に基づくタイミングでインバータ４のスイッチングを制御して同インバータ４の出力周波数を変化させるもので、いわゆるセンサレスベクトル制御を実行する。 The controller 40 includes a short circuit control unit 40 a that controls the converter 2 and an inverter control unit 40 b that controls the inverter 3. The short circuit control unit 40a controls the operation timing of the IGBT 12t of the converter 2 using the zero crossing points Pd and Pu estimated by the zero crossing detection device 20 for the improvement of the power factor and the suppression of the harmonic current. The on / off switching of the IGBT 12t of the short circuit 12 is performed in a predetermined period with reference to Pd and Pu, for example, a phase 0 ° to 60 ° and / or a specific timing within a phase 120 ° to 180 °. Since the harmonics increase as the number of on / off switching increases, it is desirable that the number of on / off switching is about 1 to 5 times. A short circuit via the reactor 11 to the AC power supply 1 is intermittently formed by the on / off switching. Along with this, the input current from the AC power supply 1 to the converter 2 becomes a sine wave without distortion. This improves the power factor. The inverter control unit 40b estimates the rotational speed of the brushless DC motor 4 from the detected current of the current sensor 5, and switches the inverter 4 at a timing based on the detected current of the current sensor 5 such that the estimated rotational speed becomes the target rotational speed. So as to change the output frequency of the inverter 4 and execute so-called sensorless vector control.
　上記コンバータ２、インバータ３、電流センサ５、ゼロクロス検出装置２０、およびコントローラ４０により、ブラシレスＤＣモータ４への駆動電力を出力する電力変換装置が構成されている。 The converter 2, the inverter 3, the current sensor 5, the zero cross detection device 20, and the controller 40 constitute a power conversion device that outputs drive power to the brushless DC motor 4.
　交流電源電圧Ｖcの波形、フォトカプラ２３の出力電圧Ｖaの波形、および演算部２９への入力電圧Ｖbの波形を図２に示す。 The waveform of the AC power supply voltage Vc, the waveform of the output voltage Va of the photocoupler 23, and the waveform of the input voltage Vb to the calculation unit 29 are shown in FIG.
　交流電源電圧Ｖcの正側半波がゼロレベルから立上がると、その立上がりに応じてフォトカプラ２３のフォトダイオード２３aが発光し、この発光を受けたフォトトランジスタ２３bがターンオンする。このターンオンに応じてフォトカプラ２３の出力電圧Ｖａがゼロレベルから立上がると、その立上がりに応じてトランジスタ２６がターンオンする。そして、このトランジスタ２６のターンオンに応じて演算部２９への入力電圧Ｖbが高レベル“H”から低レベル“L”に変化する。出力電圧Ｖaの立上がりに対する応答性が速いトランジスタ２６を用いているので、交流電源電圧Ｖcの正側半波がゼロレベルから立上がるタイミングと、入力電圧Ｖｂが高レベル“H”から低レベル“L”に変化するタイミングとの時間的な“ずれ”は非常に小さい。 When the positive half wave of the AC power supply voltage Vc rises from the zero level, the photodiode 23a of the photocoupler 23 emits light in response to the rise, and the phototransistor 23b receiving the light is turned on. When the output voltage Va of the photocoupler 23 rises from the zero level in response to the turn-on, the transistor 26 is turned on in response to the rise. Then, in response to the turning on of the transistor 26, the input voltage Vb to the operation unit 29 changes from the high level "H" to the low level "L". Since the transistor 26 having quick response to the rise of the output voltage Va is used, the timing when the positive half wave of the AC power supply voltage Vc rises from the zero level and the input voltage Vb from high level "H" to low level "L" The "time gap" with the timing which changes to "is very small.
　交流電源電圧Ｖcの正側半波が立下がると、その立下がりに応じてフォトカプラ２３のフォトダイオード２３aが消光し、この消光によりフォトトランジスタ２３bがターンオフする。このターンオフに応じてフォトカプラ２３の出力電圧Ｖaが高レベル“H”から低レベル“L”に立下がり、この立下がりに応じてトランジスタ２６がターンオフする。そして、このトランジスタ２６のターンオフに応じて演算部２９への入力電圧Ｖbが低レベル“L”から高レベル“H”に変化する。この消光側については、フォトトランジスタ２３bおよびトランジスタ２６の素子の特性上、フォトトランジスタ２３bおよびトランジスタ２６のターンオフに遅れが生じるが、この際の入力電圧Ｖｂの変化はセロクロス点の推定に用いることがないため、問題はない。なお、交流電源電圧Ｖcの正側半波の立下がり後の負側半波の期間は演算部２９への入力電圧Ｖbは高レベル“H”が維持される。 When the positive half wave of the AC power supply voltage Vc falls, the photodiode 23a of the photocoupler 23 is extinguished in response to the fall, and the phototransistor 23b is turned off by this extinction. In response to the turn-off, the output voltage Va of the photocoupler 23 falls from the high level "H" to the low level "L", and in response to this fall, the transistor 26 is turned off. Then, in response to the turn-off of the transistor 26, the input voltage Vb to the operation unit 29 changes from the low level "L" to the high level "H". On the light-off side, due to the characteristics of the elements of phototransistor 23b and transistor 26, there is a delay in turning off phototransistor 23b and transistor 26, but the change in input voltage Vb at this time is not used to estimate the cellocross point. Because, there is no problem. During the period of the negative half wave after the fall of the positive half wave of the AC power supply voltage Vc, the input voltage Vb to the calculation unit 29 is maintained at the high level "H".
　つぎに、ゼロクロス検出装置２０の演算部２９が実行する処理を図２の波形および図３のフローチャートを参照しながら説明する。フローチャートの符号S1～S22は処理ステップを示す。 Next, the process performed by the calculation unit 29 of the zero cross detection device 20 will be described with reference to the waveform of FIG. 2 and the flowchart of FIG. The symbols S1 to S22 in the flowchart indicate processing steps.
　［正側半波Ｖc1の立上がり検出］　
　コントローラ４０の制御によるインバータ３の運転開始時（S1のYES）、演算部２９は、周期指定用のカウント値ｎ、メモリ３０内の立上がり点ｔ1、処理確認用のフラグｆをそれぞれ“０”にクリアする（S2）。そして、演算部２９は、タイムカウントｔを開始するとともに（S3）、入力電圧Ｖbの高レベル“H”から低レベル“L”への変化を監視する（S4）。 [Detection of rising edge of positive half wave Vc1]
At the start of operation of inverter 3 under control of controller 40 (YES in S1), operation unit 29 sets count value n for cycle specification, rising point t1 in memory 30, and flag f for process confirmation to "0". Clear (S2). Then, the operation unit 29 starts time counting t (S3) and monitors the change of the input voltage Vb from high level "H" to low level "L" (S4).
　入力電圧Ｖbに高レベル“H” から低レベル“L”への変化がないとき（S4のNO）、演算部２９は、フラグｆを確認する（S5）。この時点のフラグｆは“０”なので（S5のNO）、演算部２９はS4の監視に戻る。 When the input voltage Vb does not change from the high level "H" to the low level "L" (NO in S4), the calculation unit 29 confirms the flag f (S5). Since the flag f at this time is "0" (NO in S5), the calculation unit 29 returns to the monitoring of S4.
　正側半波Ｖc1が立上がり、入力電圧Ｖbが高レベル“H”から低レベル“L”に変化したとき（S4のYES）、演算部２９は、カウント値ｎを“１”アップして“１”とするとともに（n=n＋1=1；S6）、この時点のタイムカウントtを交流電源電圧Ｖcの１つ目（最初）の正側半波Ｖc1の立上がり点（立上がりタイミング）ｔ2として検出しそれをメモリ３０に保持する（S7）。そして、演算部２９は、検出した立上がり点ｔ2とメモリ３０内の立上がり点ｔ1（現時点では“０”）との時間間隔を、カウント値ｎ（=1）に対応する電源周期Ｔnすなわち電源周期Ｔ1（=t2－t1）として検出する（S8）。なお、ここで、電源周期や周期とは、電源電圧の１周期に要する時間を意味している。 When the positive half wave Vc1 rises and the input voltage Vb changes from the high level “H” to the low level “L” (YES in S4), the operation unit 29 increments the count value n by “1” to “1”. (N = n + 1 = 1; S6), the time count t at this time is detected as the rising point (rising timing) t2 of the first (first) positive half wave Vc1 of the AC power supply voltage Vc. Are stored in the memory 30 (S7). Then, operation unit 29 sets the time interval between detected rising point t2 and rising point t1 ("0" at this time) in memory 30 to a power supply cycle Tn corresponding to count value n (= 1), ie, a power supply cycle T1. It is detected as (= t2-t1) (S8). Here, the power supply cycle or cycle means the time required for one cycle of the power supply voltage.
　続いて、演算部２９は、検出した電源周期Ｔ1が、下限周波数45Hzに対応する周期Ｔa以上かつ上限周波数66Hzに対応する周期Ｔc未満という適正条件（Ta≦T1＜Tc）に収まるか否かを判定する（S9）。 Subsequently, the calculation unit 29 determines whether or not the detected power supply cycle T1 falls under the appropriate condition (Ta ≦ T1 <Tc) such that the detected power supply cycle T1 is not less than the cycle Ta corresponding to the lower limit frequency 45 Hz and less than the cycle Tc corresponding to the upper limit frequency 66 Hz. It judges (S9).
　なお、インバータ３の運転開始直後の１つ目の正側半波Ｖc1の立上がりに際して検出される電源周期Ｔ1は、小さくて適正条件を満たさない可能性がある。電源周期Ｔ1が適正条件を満たさない場合（S9のNO）、演算部２９は、電源周期Ｔ1を“０”にクリアする（S10）。そして、演算部２９は、今回検出した立上がり点ｔ2を立上がり点ｔ1としてメモリ３０に更新保持する（S16）。続いて、演算部２９は、インバータ３の運転が停止でなければ（S17のNO）、上記S4に戻って入力電圧Ｖbの高レベル“H”から低レベル“L”への変化を監視する。 The power supply cycle T1 detected at the rise of the first positive half wave Vc1 immediately after the start of the operation of the inverter 3 may be small and may not satisfy the appropriate condition. If the power supply cycle T1 does not satisfy the appropriate condition (NO in S9), the calculation unit 29 clears the power supply cycle T1 to "0" (S10). Then, the operation unit 29 updates and holds the rising point t2 detected this time as the rising point t1 in the memory 30 (S16). Subsequently, when the operation of the inverter 3 is not stopped (NO in S17), the operation unit 29 returns to S4 and monitors the change of the input voltage Vb from high level "H" to low level "L".
　入力電圧Ｖbに高レベル“H”から低レベル“L”への変化がないとき（S4のNO）、演算部２９は、フラグｆを確認する（S5）。この時点のフラグｆはまだ“０”なので（S5のNO）、演算部２９はS4の監視に戻る。 When the input voltage Vb does not change from the high level "H" to the low level "L" (NO in S4), the calculation unit 29 confirms the flag f (S5). Since the flag f at this time is still "0" (NO in S5), the calculation unit 29 returns to the monitoring of S4.
　［正側半波Ｖc2の立上がり検出］　
　続いて、正側半波Ｖc2の立上がり、入力電圧Ｖbが高レベル“Ｈ”から低レベル“Ｌ”に変化したとき（S4のYES）、演算部２９は、カウント値ｎを“１”アップして“２”とするとともに（n=n＋1=2；S6）、その時点のタイムカウントtを交流電源電圧Ｖcの２つ目(最初の次)の正側半波Ｖc2の立上がり点ｔ2として検出しそれをメモリ３０に更新保持する（S7）。そして、演算部２９は、今回検出した立上がり点ｔ2とメモリ３０内の立上がり点ｔ1（前回検出した立上がり点ｔ2）との時間間隔を、カウント値ｎ（=2）に対応する電源周期Ｔnすなわち電源周期Ｔ2（=t2－t1）として検出する（S8）。 [Detection of rise of positive half wave Vc2]
Subsequently, when the positive side half wave Vc2 rises and the input voltage Vb changes from the high level “H” to the low level “L” (YES in S4), the operation unit 29 increments the count value n by “1”. And “2” (n = n + 1 = 2; S6), and the time count t at that time is detected as the rising point t2 of the second (first subsequent) positive half wave Vc2 of the AC power supply voltage Vc. It is updated and held in the memory 30 (S7). Then, operation unit 29 sets a time interval between rising point t2 detected this time and rising point t1 in memory 30 (rising point t2 detected last time) to a power supply cycle Tn corresponding to count value n (= 2), ie, power supply It is detected as a cycle T2 (= t2-t1) (S8).
　続いて、演算部２９は、検出した電源周期Ｔ2が、適正条件（Ta≦T2＜Tc）を満たすか否かを判定する（S9）。電源周期Ｔ2が適正条件を満たす場合（S9のYES）、演算部２９は、電源周期Ｔ2と基準周波数55Hzに対応する周期Ｔbとを比較する（S11）。電源周期Ｔ2が周期Ｔb以下の場合（T2≦Tb；S11のYES）、演算部２９は、電源周波数が50Hzであるとの判断の下に、今回検出した立上がり点ｔ2に電源周期Ｔ2の1/2の値および50Hz用の補正値“－Δｔa”を加えた時点（=t2＋T2/2－Δta）を上記２つ目(次回)の正側半波Ｖc2の立下がりのゼロクロス点Ｐdとして推定する（S12）。 Subsequently, the calculation unit 29 determines whether the detected power supply cycle T2 satisfies the appropriate condition (Ta ≦ T2 <Tc) (S9). If the power supply cycle T2 satisfies the appropriate condition (YES in S9), the calculation unit 29 compares the power supply cycle T2 with the cycle Tb corresponding to the reference frequency 55 Hz (S11). If the power supply cycle T2 is less than or equal to the cycle Tb (T2 ≦ Tb; YES in S11), the calculation unit 29 determines that the power supply frequency is 50 Hz and sets 1 / l of the power supply cycle T2 to the rising point t2 detected this time. The point (= t2 + T2 / 2−Δta) at which the value of 2 and the correction value “−Δta” for 50 Hz are added is estimated as the falling zero cross point Pd of the second (next) positive half wave Vc2. S12).
　電源周期Ｔ2が基準周期Ｔbより大きい場合（Tb＜T2；S11のNO）、演算部２９は、電源周波数が60Hzであるとの判断の下に、今回保持した立上がり点ｔ2に電源周期Ｔ2の1/2の値および60Hz用の補正値“－Δｔb”を加えた時点（=t2＋T2/2－Δtb）を上記２つ目(次回)の正側半波Ｖc2の立下がりのゼロクロス点Ｐdとして推定する（S13）。 If the power supply cycle T2 is larger than the reference cycle Tb (Tb <T2; NO in S11), the calculation unit 29 determines that the power supply frequency is 60 Hz, the power cycle T2 at 1 Estimate the time (= t 2 + T 2/2-Δ t b) at which the value of 2 and the correction value for -60 Hz (= t 2 + T 2/2-Δ t b) is added as the zero crossing point Pd of the second (next) positive half wave Vc 2 falling (S13).
　そして、演算部２９は、推定したゼロクロス点Ｐdをコントローラ４０の短絡制御部４０aに通知する（S14）。続いて、演算部２９は、フラグｆを“１”にセットするとともに（S15）、メモリ３０内の立上がり点ｔ2を立上がり点ｔ1としてメモリ３０に更新保持する（S16）。そして、演算部２９は、インバータ３の運転が停止でなければ（S17のNO）、上記S4に戻って入力電圧Ｖbの高レベル“H”から低レベル“L”への変化を監視する。 Then, the calculation unit 29 notifies the short circuit control unit 40a of the controller 40 of the estimated zero crossing point Pd (S14). Subsequently, the operation unit 29 sets the flag f to "1" (S15), and updates and holds the rising point t2 in the memory 30 as the rising point t1 in the memory 30 (S16). If the operation of inverter 3 is not stopped (NO at S17), operation unit 29 returns to S4 to monitor the change of input voltage Vb from high level "H" to low level "L".
　入力電圧Ｖｂに高レベル“H”から低レベル“L”への変化がないとき（S4のNO）、演算部２９は、フラグｆを確認する（S5）。この時点のフラグｆは“１”なので（S5のYES）、演算部２９は、メモリ３０内の立上がり点ｔ2に電源周期Ｔ2および補正値“－Δｔｚ”を加えた時点（=t2＋T2－Δtｚ）を３つ目(次回)の正側半波Ｖc3の立上がりのゼロクロス点Ｐuとして推定する（S18）。なお、補正値“－Δｔｚ”は、上記S11の比較結果に応じて使用される50Hz用の補正値“－Δｔa”または60Hz用の補正値“－Δｔb”のいずれか一方である。 When the input voltage Vb does not change from the high level "H" to the low level "L" (NO in S4), the calculation unit 29 confirms the flag f (S5). Since the flag f at this time is “1” (YES in S5), the calculating unit 29 sets the time (= t2 + T2-Δtz) at which the power supply cycle T2 and the correction value “−Δtz” are added to the rising point t2 in the memory 30. It is estimated as the zero cross point Pu of the rising of the third (next) positive half wave Vc3 (S18). The correction value "-.DELTA.tz" is either one of the correction value "-.DELTA.ta" for 50 Hz or the correction value "-.DELTA.tb" for 60 Hz used according to the comparison result of S11.
　そして、演算部２９は、推定したゼロクロス点Ｐuをコントローラ４０の短絡制御部４０aに通知するとともに（S19）、フラグｆを“０”にクリアする（S20）。続いて、演算部２９は、インバータ３の運転が停止していなければ（S17のNO）、上記S4に戻って入力電圧Ｖbの高レベル“H”から低レベル“L”への変化を監視する。 Then, the operation unit 29 notifies the estimated zero crossing point Pu to the short circuit control unit 40a of the controller 40 (S19), and clears the flag f to "0" (S20). Subsequently, if the operation of inverter 3 is not stopped (NO at S17), operation unit 29 returns to S4 and monitors the change of input voltage Vb from high level "H" to low level "L". .
　［正側半波Ｖｃ３の立上がり検出］　
　入力電圧Ｖbが高レベル“H”から低レベル“L”に変化したとき（S4のYES）、演算部２９は、カウント値ｎを“１”アップして“３”とするとともに（n=n＋1=3；S6）、その時点のタイムカウントtを交流電源電圧Ｖcの３つ目(最初の次の次)の正側半波Ｖc3の立上がり点ｔ2として検出しそれをメモリ３０に更新保持する（S7）。そして、演算部２９は、今回検出した立上がり点ｔ2とメモリ３０内の立上がり点ｔ1（前回検出した立上がり点ｔ2）との期間を、カウント値ｎ（=3）に対応する電源周期Ｔnすなわち電源周期Ｔ3（=t2－t1）として検出する（S8）。 [Detection of rising edge of positive half wave Vc3]
When the input voltage Vb changes from the high level “H” to the low level “L” (YES in S4), the operation unit 29 increments the count value n by “1” to “3” (n = n + 1 = 3; S6) The time count t at that time is detected as the rising point t2 of the third (first next) positive half wave Vc3 of the AC power supply voltage Vc, and is updated and held in the memory 30 ((6) S7). Then, operation unit 29 sets a period between rising point t2 detected this time and rising point t1 in memory 30 (rising point t2 detected last time) to a power supply cycle Tn corresponding to count value n (= 3), that is, a power supply cycle. It is detected as T3 (= t2-t1) (S8).
　続いて、演算部２９は、検出した電源周期Ｔ3が、適正条件（Ta≦T3＜Tc）を満たすか否かを判定する（S9）。電源周期Ｔ3が適正条件を満たす場合（S9のYES）、演算部２９は、電源周期Ｔ3と基準周波数55Hzに対応する周期Ｔbとを比較する（S11）。電源周期Ｔ3が周期Ｔb以下の場合（T3≦Tb；S11のYES）、演算部２９は、電源周波数が50Hzであるとの判断の下に、今回検出した立上がり点ｔ2に直前に検出した電源周期Ｔ3の1/2の値および50Hz用の補正値“－Δｔa”を加えた時点（=t3＋T3/2－Δta）を上記３つ目(次回)の正側半波Ｖc3の立下がりのゼロクロス点Ｐdとして推定する（S12）。 Subsequently, the calculation unit 29 determines whether the detected power supply cycle T3 satisfies the appropriate condition (Ta ≦ T3 <Tc) (S9). If the power supply cycle T3 satisfies the appropriate condition (YES in S9), the calculation unit 29 compares the power supply cycle T3 with the cycle Tb corresponding to the reference frequency 55 Hz (S11). If the power supply cycle T3 is equal to or less than the cycle Tb (T3 ≦ Tb; YES in S11), the calculation unit 29 determines that the power supply frequency is 50 Hz, the power supply cycle detected immediately before the rising point t2 detected this time. A point (= t3 + T3 / 2−Δta) at which a half value of T3 and a correction value “−Δta” for 50 Hz are added is a zero cross point Pd of the falling edge of the third (next) positive half wave Vc3. It estimates as (S12).
　電源周期Ｔ3が基準周期Ｔbより大きい場合（Tb＜T3；S11のNO）、演算部２９は、電源周波数が60Hzであるとの判断の下に、今回保持した立上がり点ｔ2に電源周期Ｔ3の1/2の値および60Hz用の補正値“－Δｔb”を加えた時点（t2＋T3/2－Δtb）を上記３つ目(次回)の正側半波Ｖc3の立下がりのゼロクロス点Ｐdとして推定する（S13）。 If the power supply cycle T3 is larger than the reference cycle Tb (Tb <T3; NO in S11), the calculation unit 29 determines that the power supply frequency is 60 Hz, and holds 1 to 1 of the power supply cycle T3 at the rising point t2 held this time. The point (t2 + T3 / 2-Δtb) at which the value of / 2 and the correction value "-Δtb" for 60 Hz are added is estimated as the zero-crossing point Pd of the falling edge of the third half wave (the next time) S13).
　そして、演算部２９は、推定したゼロクロス点Ｐdをコントローラ４０の短絡制御部４０aに通知する（S14）。続いて、演算部２９は、フラグｆを“１”にセットするとともに（S15）、メモリ３０内の立上がり点ｔ2を立上がり点ｔ1としてメモリ３０に更新保持する（S16）。そして、演算部２９は、インバータ３の運転が停止でなければ（S17のNO）、上記S4に戻って入力電圧Ｖbの高レベル“H”から低レベル“L”への変化を監視する。 Then, the calculation unit 29 notifies the short circuit control unit 40a of the controller 40 of the estimated zero crossing point Pd (S14). Subsequently, the operation unit 29 sets the flag f to "1" (S15), and updates and holds the rising point t2 in the memory 30 as the rising point t1 in the memory 30 (S16). If the operation of inverter 3 is not stopped (NO at S17), operation unit 29 returns to S4 to monitor the change of input voltage Vb from high level "H" to low level "L".
　入力電圧Ｖbに高レベル“H”から低レベル“L”への変化がないとき（S4のNO）、演算部２９は、フラグｆを確認する（S5）。この時点のフラグｆは“１”なので（S5のYES）、演算部２９は、メモリ３０内の立上がり点ｔ2に電源周期Ｔ3および補正値“－Δｔｚ”を加えた時点（=t2＋T3－Δｔｚ）を４つ目（次回）の正側半波Ｖc4の立上がりのゼロクロス点Ｐuとして推定する（S18）。 When the input voltage Vb does not change from the high level "H" to the low level "L" (NO in S4), the calculation unit 29 confirms the flag f (S5). Since the flag f at this time is “1” (YES in S5), the calculating unit 29 sets the time (= t2 + T3-Δtz) at which the power supply cycle T3 and the correction value “−Δtz” are added to the rising point t2 in the memory 30. It is estimated as the zero cross point Pu of the rising of the fourth (next) positive half wave Vc4 (S18).
　そして、演算部２９は、推定したゼロクロス点Ｐuをコントローラ４０の短絡制御部４０aに通知するとともに（S19）、フラグｆを“０”にクリアする（S20）。続いて、演算部２９は、インバータ３の運転が停止していなければ（S17のNO）、上記S4に戻って入力電圧Ｖbの高レベル“H”から低レベル“L”への変化を監視する。 Then, the operation unit 29 notifies the estimated zero crossing point Pu to the short circuit control unit 40a of the controller 40 (S19), and clears the flag f to "0" (S20). Subsequently, if the operation of inverter 3 is not stopped (NO at S17), operation unit 29 returns to S4 and monitors the change of input voltage Vb from high level "H" to low level "L". .
　［交流電源１の異常］　
　交流電源１の何らかの異常により、上記S8で検出した電源周期Ｔ3が適正条件を満たさない場合（S9のNO）、演算部２９は、電源周期Ｔ3を“０”にクリアし（S10）、今回検出した立上がり点ｔ2を立上がり点ｔ1としてメモリ３０に更新保持する（S16）。続いて、演算部２９は、インバータ３の運転が停止でなければ（S17のNO）、上記S4に戻って入力電圧Ｖbの高レベル“H”から低レベル“L”への変化を監視する。 [Abnormal power supply 1 error]
If the power supply cycle T3 detected in S8 does not satisfy the appropriate condition due to some abnormality of the AC power supply 1 (NO in S9), the arithmetic unit 29 clears the power supply cycle T3 to "0" (S10), and this time detection The rising point t2 is updated and held in the memory 30 as the rising point t1 (S16). Subsequently, when the operation of the inverter 3 is not stopped (NO in S17), the operation unit 29 returns to S4 and monitors the change of the input voltage Vb from high level "H" to low level "L".
　この場合、電源周期Ｔ3が“０”にクリアされるので、３つ目の正側半波Ｖc3の立下がりのゼロクロス点Ｐdおよび４つ目の正側半波Ｖc4の立上がりのゼロクロス点Ｐuは推定されない。次に検出されることになる４つ目の正側半波Ｖc4の立上がり点ｔ2に基づいて次の電源周期Ｔ4が検出され、その電源周期Ｔ4に基づいて、４つ目の正側半波Ｖc4の立下がりのゼロクロス点Ｐdおよび５つ目（次回）の正側半波Ｖc5の立上がりのゼロクロス点Ｐuが推定される。 In this case, since the power supply cycle T3 is cleared to “0”, the falling zero cross point Pd of the third positive half wave Vc3 and the rising zero cross point Pu of the fourth positive half wave Vc4 are estimated. I will not. The next power supply cycle T4 is detected based on the rising point t2 of the fourth positive half wave Vc4 to be detected next, and the fourth positive half wave Vc4 is detected based on the power supply cycle T4. And the rising zero cross point Pu of the fifth (next) positive side half wave Vc5 are estimated.
　［まとめ］　
　フォトカプラ２３は、フォトダイオード２３aに電流が流れてフォトトランジスタ２３bがオンするときの出力電圧Ｖaの立上がりは速いが、フォトダイオード２３aへの通電が止まってフォトトランジスタ２３bがオフするときの出力電圧Ｖaの立下がりは遅いという特性がある。このため、従来のように、フォトカプラ２３のオンとオフを交流電源電圧Ｖcのゼロクロス点として検出すると、検出に誤差を生じてしまう。 [Summary]
The photocoupler 23 has a rapid rise of the output voltage Va when the current flows through the photodiode 23a and the phototransistor 23b is turned on, but the output voltage Va when the conduction to the photodiode 23a is stopped and the phototransistor 23b is turned off. Fall is slow. For this reason, as in the prior art, when on and off of the photocoupler 23 are detected as the zero cross point of the AC power supply voltage Vc, an error occurs in detection.
　これに対し、本実施形態は、交流電源電圧の半波により発光する発光素子およびこの発光素子の発光を受けてオンする受光素子を有するフォトカプラと、このフォトカプラの出力から交流電源電圧の半波の立上がり点を検出し、検出した複数の立上がり点の相互の時間間隔を交流電源電圧の周期として検出し、検出した立上がり点より後の期間における前記交流電源電圧のゼロクロス点を前記検出した周期に基づいて推定する演算部とを備えたゼロクロス検出装置である。したがって、フォトカプラ２３の特性を考慮し、出力電圧Ｖaの立上がりに対応する正側半波の立上がり点をフォトカプラ２３を介して逐次に検出し、検出した各立上がり点から電源周期Ｔを検出し、この電源周期Ｔの検出後の期間における交流電源電圧Ｖcの正負のゼロクロス点Ｐd，Ｐuを実際に検出した電源周期Ｔに基づいて推定するので、交流電源電圧Ｖcのゼロクロス点Ｐd，Ｐuを誤差なく的確に捕えることができる。例えば、電源周波数が50Hzか60Hzのいずれかを判別し、電源周波数が50Hzであれば電源周期Ｔは20msecであると認識し、その電源周期Ｔ＝20msecを用いて次回の正側半波のゼロクロス点を推定し、電源周波数が60Hzであれば電源周期Ｔは16.7msecであると認識し、その電源周期Ｔ＝16.7msecを用いて次回の正側半波のゼロクロス点を推定することもできるが、電力事情の関係から電源周波数が不安定な地域でそのような推定を行うと、推定結果に誤差が生じてしまう。これに対して、本実施形態では、正側半波の立上がり点を逐次に検出し、検出した各立上がり点から実際の電源周期Ｔを検出し、検出した電源周期Ｔに基づいて次回及び次々回のゼロクロス点Ｐd，Ｐuを推定するので、地域の電源事情にかかわらず、ゼロクロス点Ｐd，Ｐuを正確に推定できる。 On the other hand, in the present embodiment, a light emitting element emitting light by a half wave of an AC power supply voltage and a photo coupler having a light receiving element turned on in response to the light emission of the light emitting element The rising point of the wave is detected, the time interval between the detected rising points is detected as the period of the AC power supply voltage, and the zero crossing point of the AC power supply voltage in the period after the detected rising point is detected And an operation unit that estimates based on the above. Therefore, in consideration of the characteristics of photocoupler 23, the rising point of the positive half wave corresponding to the rising of output voltage Va is sequentially detected through photocoupler 23, and power supply cycle T is detected from each detected rising point. Since the positive and negative zero cross points Pd and Pu of the AC power supply voltage Vc in the period after the detection of the power supply cycle T are estimated based on the actually detected power supply cycle T, the zero cross points Pd and Pu of the AC power supply voltage Vc are You can catch it properly. For example, the power supply frequency determines either 50 Hz or 60 Hz, and if the power supply frequency is 50 Hz, it recognizes that the power supply cycle T is 20 msec, and uses the power supply cycle T = 20 msec to make the next positive half-wave zero cross The point can be estimated, and if the power supply frequency is 60 Hz, the power supply cycle T can be recognized to be 16.7 msec, and the zero crossing point of the next positive half wave can also be estimated using the power supply cycle T = 16.7 msec. If such estimation is performed in an area where the power supply frequency is unstable due to the power situation, an error occurs in the estimation result. On the other hand, in the present embodiment, the rising points of the positive half wave are sequentially detected, the actual power supply cycle T is detected from each detected rising point, and the next and the next time on the basis of the detected power supply cycle T. Since the zero crossing points Pd and Pu are estimated, the zero crossing points Pd and Pu can be accurately estimated regardless of the local power supply situation.
　交流電源電圧Ｖcのゼロクロス点Ｐd，Ｐuを的確に捕えることができるので、コントローラ４０による力率の改善や高調波電流の抑制の効果を確実に得ることができる。 Since the zero cross points Pd and Pu of the AC power supply voltage Vc can be accurately captured, the effects of the improvement of the power factor and the suppression of the harmonic current by the controller 40 can be surely obtained.
　ゼロクロス点Ｐd，Ｐuの推定に補正値“－Δｔ”を加味するので、交流電源電圧Ｖcの値の変動、フォトカプラ２３のCTRの変動、フォトカプラ２３の周囲温度変動などを要因とするフォトカプラ２３の応答遅れに影響を緩和することができ、この点でも、ゼロクロス点Ｐd，Ｐuを正確に推定することができる。さらにゼロクロス点Ｐd，Ｐuの推定に、電源周波数に基づく補正値“－Δｔa”,“－Δｔb”を加味するので、ゼロクロス点Ｐd，Ｐuをより正確に推定することができる。 Since the correction value “−Δt” is added to the estimation of the zero cross points Pd and Pu, a photocoupler that takes fluctuation of the value of the AC power supply voltage Vc, fluctuation of CTR of the photocoupler 23, ambient temperature fluctuation of the photocoupler 23, etc. The influence on the response delay of 23 can be mitigated, and also at this point, the zero crossing points Pd and Pu can be accurately estimated. Further, since the correction values “−Δta” and “−Δtb” based on the power supply frequency are added to the estimation of the zero crossing points Pd and Pu, the zero crossing points Pd and Pu can be estimated more accurately.
　ダイオード２１およびフォトダイオード２３aを用いることによって交流電源電圧Ｖcの正側半波のみをフォトカプラ１２のフォトダイオード２３aに加える構成であるから、交流電源電圧Ｖcの負側半波の期間中はフォトダイオード２３aには電流が流れず、よって消費電力の低減が図れる。しかも、交流電源１に接続されるフォトダイオード２３aへの通電路に消費電力低減用の抵抗器２２を配置しているので、さらなる電力の低減ができる。 Since only the positive half wave of the AC power supply voltage Vc is applied to the photodiode 23a of the photocoupler 12 by using the diode 21 and the photodiode 23a, the photodiode during the negative half wave of the AC power supply voltage Vc No current flows to 23a, and hence the power consumption can be reduced. In addition, since the resistor 22 for reducing power consumption is disposed in the conduction path to the photodiode 23a connected to the AC power supply 1, power can be further reduced.
　［変形例］　
　上記実施形態では、交流電源電圧Ｖcの正側半波の立上がり点をフォトカプラ２３で検出する構成としたが、ダイオード２１の極性およびフォトダイオード２３ａの極性をそれぞれ図１の状態とは逆に接続し、交流電源電圧Ｖcの負側半波の立上がり点を検出する構成としてもよい。交流電源電圧Ｖcの負側半波の立上がりとは、交流電源電圧Ｖcがゼロレベルから負側のピークレベルに向かい変化していく様子のことである。 [Modification]
In the above embodiment, the rising point of the positive half wave of the AC power supply voltage Vc is detected by the photocoupler 23, but the polarity of the diode 21 and the polarity of the photodiode 23a are respectively connected reversely to the state of FIG. Alternatively, the rising point of the negative half wave of the AC power supply voltage Vc may be detected. The rising of the negative half wave of the AC power supply voltage Vc means that the AC power supply voltage Vc changes from the zero level toward the peak level on the negative side.
　この構成の場合、交流電源電圧Ｖcの負側半波のみがフォトカプラ１２のフォトダイオード２３aに加わるので、交流電源電圧Ｖcの正側半波の期間中はフォトダイオード２３aには電流が流れず、よって消費電力の低減が図れる。また、フォトカプラ２３のフォトダイオード２３ａに交流電源電圧Ｖcの負側半波が加わるので、フォトカプラ２３の出力電圧Ｖaのゼロレベルからの立上がり点が交流電源電圧Ｖcの負側半波の立上がり点にほぼ同期する。 In this configuration, only the negative half wave of the AC power supply voltage Vc is applied to the photodiode 23a of the photocoupler 12, so no current flows in the photodiode 23a during the positive half wave of the AC power supply voltage Vc. Therefore, power consumption can be reduced. Further, since the negative half wave of AC power supply voltage Vc is applied to photodiode 23a of photocoupler 23, the rising point from the zero level of output voltage Va of photocoupler 23 is the rising point of the negative half wave of AC power supply voltage Vc. Approximately sync with
　演算部２９は、交流電源電圧Ｖcの負側半波の立上がりのゼロクロス点Ｐuおよび交流電源電圧Ｖcの負側半波の立下がりのゼロクロス点Ｐdを推定する。交流電源電圧Ｖcの負側半波の立上がりのゼロクロス点Ｐuとは、交流電源電圧Ｖcが正側レベルから負側レベルに向かい変化してゼロレベルを横切る時点のことである。交流電源電圧Ｖcの負側半波の立下がりのゼロクロス点Ｐdとは、交流電源電圧Ｖcが負側のピークレベルからゼロレベルに向かい変化してゼロレベルを横切る時点のことである。 Arithmetic unit 29 estimates the zero cross point Pu of the rise of the negative half wave of AC power supply voltage Vc and the zero cross point Pd of the fall of the negative half wave of AC power supply voltage Vc. The zero cross point Pu of the rise of the negative half wave of the AC power supply voltage Vc is the time when the AC power supply voltage Vc changes from the positive level to the negative level and crosses the zero level. The falling zero cross point Pd of the negative half wave of the AC power supply voltage Vc is a point when the AC power supply voltage Vc changes from the negative peak level toward the zero level and crosses the zero level.
　また、上記実施形態では、推定したゼロクロス点Ｐd，Ｐuを力率の改善のためのオン，オフスイッチング制御に用いる場合を例に説明したが、それに限らず、推定したゼロクロス点Ｐd，Ｐuを種々の制御へ利用することが可能である。たとえば、交流電源の交流を昇圧して直流化する昇圧チョッパ―回路やＰＷＭコンバータのスイッチング素子のオン，オフタイミングの基準に適用することで、力率改善や高調波電流の抑制もできる。 In the above embodiment, the estimated zero crossing points Pd and Pu are used for on / off switching control to improve the power factor. However, the estimated zero crossing points Pd and Pu are not limited to the above. Can be used to control the For example, power factor improvement and suppression of harmonic current can also be performed by applying to a reference of on / off timing of a switching element of a step-up chopper circuit or a switching element of a step-up chopper circuit or a PWM converter which boosts alternating current of alternating current power.
　その他、上記実施形態および変形例は、例として提示したものであり、発明の範囲を限定することは意図していない。この新規な実施形態および変形例は、その他の様々な形態で実施されることが可能であり、発明の要旨を逸脱しない範囲で、種々の省略、書き換え、変更を行うことができる。これら実施形態や変形は、発明の範囲は要旨に含まれるとともに、特許請求の範囲に記載された発明とその均等の範囲に含まれる。 In addition, the above embodiments and modifications are presented as examples, and are not intended to limit the scope of the invention. This novel embodiment and modification can be implemented in other various forms, and various omissions, rewrites and changes can be made without departing from the scope of the invention. These embodiments and modifications are included in the scope of the invention in the scope, and are included in the invention described in the claims and the equivalents thereof.
　１…交流電源、２…コンバータ、３…インバータ、４…ブラシレスＤＣモータ、１１…リアクタ、１２…短絡回路、１３…全波整流回路、１４…平滑コンデンサ、２０…ゼロクロス検出装置、２１…半波整流用のダイオード、２２…消費電力低減用の抵抗器、２３…フォトカプラ、２３a…フォトダイオード（発光素子）、２３b…フォトトランジスタ（受光素子）、２４a…正側端子、２４b…負側端子、２５a，２５b…抵抗器、２６…ＮＰＮ型トランジスタ、２９…演算部、３０…メモリ、４０…コントローラ DESCRIPTION OF SYMBOLS 1 ... AC power supply, 2 ... Converter, 3 ... Inverter, 4 ... Brushless DC motor, 11 ... Reactor, 12 ... Short circuit, 13 ... Full wave rectifier circuit, 14 ... Smoothing capacitor, 20 ... Zero cross detection apparatus, 21 ... Half wave Diode for rectification, 22: Resistor for power consumption reduction, 23: Photocoupler, 23a: Photodiode (light emitting element), 23b: Phototransistor (light receiving element), 24a: Positive side terminal, 24b: Negative side terminal, 25a, 25b ... resistor, 26 ... NPN type transistor, 29 ... operation unit, 30 ... memory, 40 ... controller

Claims (7)

  1. 　交流電源電圧の半波により発光する発光素子およびこの発光素子の発光を受けてオンする受光素子を有するフォトカプラと、
    　前記フォトカプラの出力から前記交流電源電圧の半波の立上がり点を逐次に検出し、検出した立上がり点のうち最後に検出した立上がり点と最後より１つ前に検出した立上がり点との時間間隔を前記交流電源電圧の周期として検出し、前記最後に検出した立上がり点に前記検出した周期の1/2の値を加えた時点を、前記最後に検出した立上がり点の後の前記交流電源電圧の最初の半波のゼロクロス点として推定し、前記最後に検出した立上がり点に前記検出した周期を加えた時点を、前記最初の半波の次の半波のゼロクロス点として推定する演算部と、
    　を備えることを特徴とするゼロクロス検出装置。     A light emitting element which emits light by a half wave of an AC power supply voltage, and a photocoupler having a light receiving element which is turned on in response to the light emission of the light emitting element;
    The rising point of the half wave of the AC power supply voltage is sequentially detected from the output of the photocoupler, and the time interval between the last detected rising point of the detected rising points and the rising point detected one before the last The time point of detection as the cycle of the AC power supply voltage and adding a half of the detected cycle to the last detected rising point is the first of the AC power supply voltage after the last detected rising point An arithmetic unit for estimating as a zero crossing point of a half wave of the first half wave and estimating a time point when the detected period is added to the rising point detected last, as a zero crossing point of the next half wave of the first half wave;
    A zero cross detection device comprising:
  2. 　前記演算部は、前記最後に検出した立上がり点に前記検出した周期の1/2の値および補正値を加えた時点を、前記最後に検出した立上がり点の後の前記交流電源電圧の最初の半波のゼロクロス点として推定し、前記最後に検出した立上がり点に前記検出した周期および前記補正値を加えた時点を、前記最初の半波の次の半波のゼロクロス点として推定する、
    　前記補正値は、前記交流電源電圧の値、前記フォトカプラのＣＴＲ、前記フォトカプラの周囲温度の少なくとも１つをパラメータとして求めた値である、
    　ことを特徴とする請求項１に記載のゼロクロス検出装置。     The arithmetic operation unit is configured to add a half of the detected period and the correction value to the last detected rising point, and the first half of the AC power supply voltage after the last detected rising point. Estimating the time as the zero crossing point of the wave, and estimating the time point when the detected period and the correction value are added to the last detected rising point as the zero crossing point of the next half wave of the first half wave,
    The correction value is a value obtained by using at least one of the value of the AC power supply voltage, the CTR of the photocoupler, and the ambient temperature of the photocoupler as a parameter.
    The zero-crossing detection device according to claim 1, characterized in that:
  3. 　前記交流電源電圧の正側半波を前記フォトカプラの発光素子に印加するダイオードと、
    　前記フォトカプラの受光素子のオンによるその受光素子の出力電圧の立上がりに応じてターンオンし同出力電圧の立下がりに応じてターンオフする半導体スイッチと、
    　をさらに備え、
    　前記演算部は、前記半導体スイッチのターンオンを前記交流電源電圧の正側半波の立上がり点として検出する、
    　ことを特徴とする請求項１または請求項２に記載のゼロクロス検出装置。     A diode for applying a positive half wave of the AC power supply voltage to a light emitting element of the photocoupler;
    A semiconductor switch which is turned on in response to the rise of the output voltage of the light receiving element when the light receiving element of the photocoupler is turned on, and is turned off in response to the fall of the output voltage;
    And further
    The arithmetic unit detects turn-on of the semiconductor switch as a rising point of a positive half wave of the AC power supply voltage.
    The zero cross detection apparatus according to claim 1 or 2, wherein
  4. 　前記交流電源電圧の正側半波を前記フォトカプラの発光素子に印加するダイオードと、
    　直流定電圧が印加される正側端子および負側端子のうち正側端子に一端が接続された抵抗器と、
    　前記抵抗器の他端に接続されるコレクタ、前記負側端子に接続されるエミッタ、前記抵抗器の一端に前記受光素子を介して接続されるベースを有し、ベースとエミッタとの間に印加される電圧が規定値以上に上昇した場合にターンオンし所定値未満に下降した場合にターンオフするトランジスタと、
    　を備え、
    　前記演算部は、前記トランジスタのターンオンを前記交流電源電圧の正側半波の立上がり点として検出する、
    　ことを特徴とする請求項１または請求項２に記載のゼロクロス検出装置。     A diode for applying a positive half wave of the AC power supply voltage to a light emitting element of the photocoupler;
    A resistor of which one end is connected to the positive terminal among the positive terminal and the negative terminal to which a constant DC voltage is applied;
    It has a collector connected to the other end of the resistor, an emitter connected to the negative terminal, a base connected to one end of the resistor via the light receiving element, and is applied between the base and the emitter A transistor that is turned on when the voltage being raised rises above a specified value and turned off when
    Equipped with
    The arithmetic unit detects turn-on of the transistor as a rising point of a positive half wave of the AC power supply voltage.
    The zero cross detection apparatus according to claim 1 or 2, wherein
  5. 　前記フォトカプラの発光素子への通電路に配置された消費電力低減用の抵抗器、
    　をさらに備えることを特徴とする請求項３または請求項４に記載のゼロクロス検出装置。     A resistor for reducing power consumption disposed in a current path to the light emitting element of the photocoupler,
    The zero-crossing detection apparatus according to claim 3 or 4, further comprising:
  6. 　前記フォトカプラの発光素子は、前記交流電源電圧の正側半波で動作するフォトダイオードであることを特徴とする請求項３または請求項４に記載のゼロクロス検出装置。 The light emitting element of the said photocoupler is a photodiode which operate | moves by the positive half wave of the said alternating current power supply voltage, The zero crossing detection apparatus of Claim 3 or Claim 4 characterized by the above-mentioned.
  7. 　請求項１ないし６に記載されたゼロクロス検出装置によって推定されたゼロクロス点を用いてコンバータのスイッチング素子の動作タイミングを制御するコントローラを備えた電力変換装置。 A power converter comprising a controller for controlling the operation timing of switching elements of the converter using the zero crossing point estimated by the zero crossing detection device according to any one of claims 1 to 6.
PCT/JP2017/045998 2017-12-21 2017-12-21 Zero-crossing detection device and power conversion device WO2019123618A1 (en)

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