JP5222985B2 - Power regeneration converter, motor drive system, and power regeneration processing method - Google Patents

Description

  The disclosed embodiments relate to a power regeneration converter having a power regeneration function, a motor drive system, and a power regeneration processing method.

  Patent Document 1 discloses a technique related to a servo drive device including a three-phase bridge rectifier circuit and an inverter circuit each capable of power supply regeneration control, and a smoothing capacitor. In this prior art, when the peak value of the AC voltage slightly exceeds the DC voltage value of the smoothing capacitor, the three-phase bridge rectifier circuit is intermittently short-circuited, and the charging current flows to the smoothing capacitor. This is based on the idea that harmonics are generated from the inside of the phase bridge rectifier circuit. As a countermeasure, when a three-phase AC power supply voltage with a peak value exceeding the DC voltage value of the smoothing capacitor is input, the distortion of the voltage and current of the three-phase AC power supply is prevented by a simple circuit configuration. Therefore, there is disclosed a technique capable of avoiding generation of harmonics and deterioration of power factor and preventing noise interference to other circuits due to generation of harmonics.

Japanese Patent No. 2872210

  On the other hand, in recent years, for example, when exporting electrical products from Japan to Europe, CE marking based on the EMC Directive is required, and depending on the country of use, the product cannot be used unless the standard based on this EMC Directive is satisfied. is there. The EMC directive requires both EMI (electro-magnetic interference) for evaluating electromagnetic waves leaking from the device and EMS (electro-magnetic sustainability) for evaluating the resistance of the device to external electromagnetic waves.

  In the above prior art, harmonics may be applied to the AC voltage itself input from the AC power supply due to generation of harmonics from other devices connected to the same AC power supply. The countermeasure against the above-mentioned EMS which evaluates tolerance to such a harmonic derived from the outside is not made.

  For example, in the motor operation sequence, when the electric power regenerated when the motor is decelerated and stopped is charged to the smoothing capacitor via the inverter, at what point the regenerative control from the converter side to the AC power supply is started. It is necessary to appropriately determine the start timing. However, when harmonics are constantly applied to the AC voltage, the charging voltage of the smoothing capacitor boosts according to the voltage amplitude of the harmonics, while the normal AC voltage detection method can detect harmonic components. Only normal AC voltage values can be detected. For this reason, in the simple comparison between the AC voltage and the DC voltage, it is easy to erroneously determine the start timing of the regeneration control on the converter side.

  The present invention has been made in view of such problems, and a power regeneration converter, a motor drive system, and a power source that can perform power regeneration processing at an appropriate start timing regardless of the presence or absence of harmonics applied to an AC power source. It aims at providing the regeneration processing method.

  In order to solve the above-described problem, according to one aspect of the present invention, an alternating current detection unit that detects an alternating current flow state of each phase of an input alternating current power supply, and a direct current voltage obtained by full-wave rectifying the alternating current power supply. A regenerative converter unit comprising: a rectifier bridge circuit that outputs a pair; and a regenerative switching unit in which a pair of two semiconductor switching elements connected in series is connected in parallel corresponding to each phase of the rectifier bridge circuit; A smoothing capacitor for smoothing the voltage, and switching the semiconductor switching element of the regenerative converter unit at a start timing determined by a start determination process based on the alternating current flow state detected by the alternating current detection unit, and the direct current A converter regeneration control unit that performs power regeneration processing so that regenerative power generated on the voltage side is returned to the AC power supply. Over data is applied.

  In order to solve the above problem, according to one aspect of the present invention, an alternating current detection unit that detects an alternating current flow state of each phase of an input alternating current power supply and a full wave rectification of the alternating current power supply A regenerative converter unit comprising: a rectifier bridge circuit that outputs a DC voltage; and a regenerative switching unit in which a set of two semiconductor switching elements connected in series is connected in parallel corresponding to each phase of the rectifier bridge circuit; A smoothing capacitor for smoothing the DC voltage, and switching the semiconductor switching element of the regenerative converter unit at a start timing determined by a start determination process based on the AC current flow state detected by the AC current detection unit, A converter regeneration control unit for performing a power regeneration process so as to return the regenerative power generated on the DC voltage side to the AC power supply; And an inverter control unit that PWM-controls the inverter unit so as to supply desired power to the motor connected to the inverter unit based on a motor control command from the host controller. A motor drive system is applied.

  In order to solve the above problem, according to one aspect of the present invention, a rectifier bridge circuit that outputs a DC voltage by full-wave rectifying an input AC power supply and two semiconductor switching elements are connected in series. A regenerative switching unit having a pair connected in parallel corresponding to each phase of the rectifier bridge circuit, and a power regeneration processing method for executing the set on a regenerative converter unit, the alternating current of each phase of the AC power source The semiconductor switching elements of the regenerative converter unit are respectively switched at the start timing determined in the AC current detection step for detecting the distribution state and the start determination process based on the AC current distribution state detected in the AC current detection step. And a converter regeneration control step for performing a power regeneration process so as to return the regenerative power generated on the DC voltage side to the AC power supply. Sources regeneration processing method is applied.

  According to the present invention, the power regeneration process can be performed at an appropriate start timing regardless of the presence or absence of harmonics applied to the AC power supply.

It is the block diagram which showed typically the structure of the motor drive system which concerns on one Embodiment. It is the figure which simplified the circuit structure of FIG. 1 and showed the electric current and voltage of each place which should pay attention. It is the figure which compared and showed the full wave rectification waveform of the three-phase alternating current voltage when there is no application of a harmonic. It is the figure which compared and showed the full wave rectification waveform of the three-phase alternating current voltage in case there exists application of a harmonic. It is a time chart which shows the change of DC voltage and AC voltage when a harmonic is applied. It is a time chart which shows the change of an alternating current and a direct-current voltage at the time of starting determination by a comparative conventional system in the state where a harmonic was applied. It is a time chart which shows the change of an alternating current, a direct-current voltage, and a reference voltage at the time of starting determination by the system of an embodiment in the state where a harmonic is not applied. It is a time chart which shows the change of an alternating current, a direct-current voltage, and a reference voltage at the time of starting determination by the system of an embodiment in the state where a harmonic was applied. It is a flowchart of the start determination process which CPU which a converter regeneration control part provides is performed.

  Hereinafter, an embodiment will be described with reference to the drawings.

  In FIG. 1, a motor drive system 100 drives a three-phase AC motor 300 using electric power supplied from an AC power supply 200, and includes a power regeneration converter 1 and a motor drive device 3. In this example, the three-phase AC motor 300 is assumed to be a rotary motor and corresponds to the motor described in each claim.

  The power regeneration converter 1 includes a regeneration converter unit 11, a smoothing capacitor 2, an alternating current detection unit 12, an alternating voltage detection unit 13, and a converter regeneration control unit 14.

  The regenerative converter unit 11 is a device in which six arm switching elements 51 formed of a semiconductor such as IGBT and six diodes 52 are bridge-connected. Specifically, two circuits in which the arm switching element 51 and the diode 52 are connected in parallel are connected in series to form one set, and three sets are connected in parallel to the smoothing capacitor 2. When the AC power corresponding to the phase is input to the intermediate connection position of each set, each diode 52 performs full-wave rectification on the three-phase AC power and outputs DC power to the smoothing capacitor 2. That is, all the diodes 52 are connected in the forward direction from the input side from the AC power source 200 to the output side to the smoothing capacitor 2. Also, each arm switching element 51 receives a gate signal from the converter regeneration control unit 14 so that the DC power on the smoothing capacitor 2 side corresponds to each phase of the AC power supply 200 from the intermediate connection position of each set. Switch to regenerate power. This power regeneration process in the regenerative converter unit 11 is hereinafter referred to as converter-side power regeneration process. In the case where the AC power supply 200 is a single phase, the regenerative converter unit 11 only needs to rectify single-phase AC power and output DC power. Further, the converter-side power regeneration process corresponds to the power regeneration process described in each claim.

  The smoothing capacitor 2 is connected so as to pass between the DC buses on the output side of the power regeneration converter 1, and smoothes the DC voltage Vdc that is full-wave rectified by the six diodes 52 of the power regeneration converter 1.

  In this example, the alternating current detection unit 12 is a current detector using CT (Current Transformer), and the flow state of the alternating current (Iac in the figure) between the alternating current power source 200 and the regenerative converter unit 11 is shown for each phase. Detect every time.

  In this example, the AC voltage detection unit 13 is a full-wave rectifier in which six diodes are bridge-connected, and the AC voltage of the AC power supply 200 is full-wave rectified, and this detected voltage value is a reference value of the magnitude of the AC power supply voltage. It is detected as a certain full-wave rectified voltage (Vac in the figure).

  The converter regeneration control unit 14 includes a CPU, a ROM, a RAM, and the like. The AC current Iac detected by the AC current detection unit 12, the full-wave rectified voltage Vac detected by the AC voltage detection unit 13, and Based on the DC voltage (Vdc in the figure) between the DC buses to which the smoothing capacitor 2 is connected, the start timing of the converter-side power regeneration process is determined. When the converter-side power regeneration process is started, a gate signal is output and controlled to each arm switching element 51 of the regenerative converter unit 11.

  The motor drive device 3 includes an inverter unit 31 and an inverter control unit 32.

  The inverter unit 31 is a device in which six arm switching elements 61 made of a semiconductor such as an IGBT and six diodes 62 are bridge-connected. Specifically, two circuits in which the arm switching element 61 and the flywheel diode (FWD) diode 62 are connected in parallel are connected in series to form one set, and three sets are connected in parallel to the smoothing capacitor 2. Each arm switching element 61 receives the gate signal from the inverter control unit 32, so that the DC power on the smoothing capacitor 2 side corresponds to each phase of the three-phase AC motor 300 from the intermediate connection position of each set. And switching to output. Further, for example, when the three-phase AC motor 300 is in a sudden deceleration operation, the three-phase AC motor 300 operates as a generator, so that the three-phase AC motor 300 is changed to a DC circuit in the power regeneration converter 1 including the smoothing capacitor 2. Regenerative power that flows backward is generated. In other words, when the motor operates as a generator, rotational (kinetic) energy is converted into regenerative power (regenerative energy), and the internal power supply converter 1 in the power regeneration converter 1 passes through the diode 62 in the inverter unit 31 from the three-phase AC motor 300. Flow into the DC circuit. This regenerative operation in the inverter unit 31 is hereinafter referred to as inverter-side regenerative operation. If the DC circuit that generates DC for the inverter from the AC power source is a simple diode rectifier that does not have power regeneration processing capability, regenerative power that has flowed into the DC circuit during the inverter side regenerative operation must be regenerated to the AC power source. Therefore, there is a possibility that regenerative power is accumulated in the smoothing capacitor 2 in the DC circuit and the DC voltage rises and becomes overvoltage.

  The inverter control unit 32 includes a CPU, a ROM, a RAM, and the like. The inverter control unit 32 is configured so that the three-phase AC motor 300 supplies desired power based on a motor control command from a host control device 33 provided separately. Each arm switching element 61 is controlled by outputting a gate signal based on PWM control.

  Although not particularly shown in FIG. 1, the power from each AC power source 200 is supplied to the power line of each phase between the AC power source 200 and the power source regenerative converter 1 when the power source regenerative converter 1 is turned on. A reactor is provided to prevent abrupt flow into converter 1 or to prevent the power regenerated by the converter-side power regeneration process from rapidly flowing back toward AC power supply 200.

  Here, with reference to FIG. 2 showing a simplified circuit configuration of the motor drive system 100, changes in internal parameters at various locations in each operation sequence of the three-phase AC motor 300 will be described. The internal parameters to be noted when knowing the operation status of the motor drive system 100 are the distribution state of the alternating current Iac and the full-wave rectified voltage Vac between the AC power source 200 and the regenerative converter unit 11, and the regenerative converter unit 11-the smoothing capacitor 2. -DC voltage Vdc in the DC bus between the inverter units 31. These AC current Iac, full-wave rectified voltage Vac, and DC voltage Vdc are actually detected by the power regeneration converter 1.

  Note that the configuration of the regenerative converter unit 11 described above includes a rectifier bridge circuit 11a capable of full-wave rectification by connecting a diode 52 in the forward direction from the input side to the output side, as shown in FIG. This is equivalent to a configuration in which a regenerative switching circuit 11b in which a set of arm switching elements 51 connected in series is connected in parallel for each phase is connected in parallel for each phase. In addition, the configuration of the inverter unit 31 described above is a set of two circuits in which an arm switching element 61 and a diode 62 as a flywheel diode (FWD) are connected in series as shown in FIG. This is equivalent to a configuration in which three sets of the smoothing capacitor 2 are connected in parallel.

  In the motor drive system 100 including the regenerative converter unit 11 and the inverter unit 31, when driving power is supplied from the AC power source 200 to the three-phase AC motor 300 in the forward direction, the driving power is transmitted via the regenerative converter unit 11. Thus, the inverter unit 31 supplies the switching control. Conversely, when regenerative power generated by the three-phase AC motor 300 is regenerated to the AC power source 200 in the reverse direction, the regenerative power is switched by the regenerative converter unit 11 via the inverter unit 31. The power is regenerated.

  The switching control method in the regenerative converter unit 11 includes, for example, a PWM control method and a 120 ° energization method. In the example of the present embodiment, a 120 ° energization method that performs switching control in accordance with the phase of each phase of the AC power supply 200 is applied to the converter-side power regeneration processing in the regenerative converter unit 11. The 120 ° energization method may be controlled by a known method, and detailed description thereof is omitted here.

  In the following, it is assumed that the normal AC voltage itself of the AC power supply 200 is maintained constant.

<1. When no harmonics are applied>
First, a normal case where no harmonics are applied to the AC power supply 200 will be described.
(1-A: At start-up) First, at the start-up immediately after the power is turned on from the initial state where the entire motor drive system 100 is completely discharged and not energized, the full-wave rectified voltage Vac> the DC voltage Vdc. Therefore, the regenerative converter unit 11 full-wave rectifies the AC power, and the smoothing capacitor 2 is forward charged. Further, at this time, the initial gain is automatically adjusted so that the relationship of full-wave rectified voltage Vac × automatic adjustment gain≈DC voltage Vdc is obtained by a voltage automatic adjustment function provided separately. Naturally, during this initial charging, the alternating current Iac is in a state of flowing in the direction from the alternating current power supply 200 to the power regeneration converter 1.

  (1-B: Before motor driving) And before motor driving, the above-described voltage automatic adjustment function maintains the relationship of full-wave rectified voltage Vac × automatic adjustment gain≈DC voltage Vdc. Before the motor is driven, since the power regeneration converter 1 and the motor drive device 3 are energized, the alternating current Iac is circulated in the direction from the alternating current power supply 200 to the power regeneration converter 1. .

  (1-C: When driving the motor) When the inverter control unit 32 performs switching control by PWM control on each arm switching element 61 of the inverter unit 31 and drives the three-phase AC motor 300 to be fed (drive of the three-phase AC motor 300) In the case of acceleration or constant speed driving), since the charging power of the smoothing capacitor 2 is consumed for motor driving, the full-wave rectified voltage Vac> the DC voltage Vdc, but the relationship of the full-wave rectified voltage Vac≈the DC voltage Vdc is satisfied. The regenerative converter unit 11 rectifies the AC voltage so that the smoothing capacitor 2 is charged in order as needed. At this time, naturally, the AC current Iac circulates in the direction from the AC power supply 200 to the power regeneration converter 1.

(1-D: During inverter side regenerative operation (before converter side power regeneration process))
As described above, when the three-phase AC motor 300 is driven at a reduced speed, the inverter side regeneration operation is performed. That is, the regenerative power from the three-phase AC motor 300 flows into the DC circuit in the power supply regenerative converter 1 via the diode 62 in the inverter unit 31. At this time, since the converter side power regeneration processing in the power regeneration converter 1 has not been started, the regenerative power is accumulated in the smoothing capacitor 2 (reverse charging), and the DC voltage Vdc is boosted. At this time, the alternating current Iac at the stage where the full-wave rectified voltage Vac> the direct-current voltage Vdc is in a flowing state in the direction from the alternating-current power supply 200 to the power regeneration converter 1, and the full-wave rectified voltage Vac <direct-current voltage as the direct-current voltage Vdc is boosted. The alternating current Iac at the stage where the voltage reaches Vdc is in a disconnected state.

  (1-E: During converter-side power regeneration processing) During the inverter-side regeneration operation, the DC voltage Vdc continues to be boosted, but the converter-side power regeneration processing in the regeneration converter unit 11 is started at an appropriate start timing and smoothed. The regenerative power accumulated in the capacitor 2 is regenerated in the AC power supply 200. In this example, the converter-side power regeneration process is appropriately performed by the 120 ° energization method described above to lower the DC voltage Vdc to the same potential as the full-wave rectified voltage Vac, and then the full-wave rectified voltage Vac≈DC voltage Vdc. The regenerative power is regenerated to the AC power source 200 so as to maintain the relationship. At this time, naturally, the alternating current Iac is in a state of flowing in the direction from the power regeneration converter 1 to the alternating current power supply 200 (the direction in which the alternating current Iac flows is the above (1-A) (1-B) ( Reverse direction to 1-C). Then, after the inverter-side regenerative operation is completed, the converter-side power regeneration process is canceled to return to the time before the motor driving (1-B), and the full-wave rectified voltage Vac × automatic adjustment is performed by the above-described automatic voltage adjustment function. The relationship of gain≈DC voltage Vdc is maintained.

  Then, in the state in which the DC voltage Vdc is being boosted by the inverter-side regenerative operation (1-D), the timing for starting the converter-side power regeneration process (1-E) is as a conventional general method. For example, the converter-side power regeneration process has been started on the condition that the difference between the DC voltage Vdc and the full-wave rectified voltage Vac is a predetermined value or more (for example, 40 V or more for the 400 V system). That is, when the DC voltage Vdc is larger than the predetermined value than the full-wave rectified voltage Vac, the converter-side power supply prevents the regenerative power from accumulating in the smoothing capacitor 2 and the DC voltage Vdc to rise to generate an overvoltage. In this method, regeneration processing is performed and power regeneration to the AC power source 200 is started.

  The above operation sequences (1-A) to (1-E) are based on a normal case where no harmonics are applied to the AC power supply 200. In this case, as shown in FIG. 3, the full-wave rectified voltage Vac detected by the AC voltage detector 13 is detected as an execution value including the pulsation of the full-wave rectified three-phase AC voltage. On the other hand, the DC voltage Vdc fluctuates to the same potential as the charging voltage of the smoothing capacitor 2, and as described above, the driving state of the motor driving device 3 (above (1-C)) and the regenerative state (above (1-D )) To increase or decrease pressure. Usually, the peak value of the three-phase AC voltage that has been full-wave rectified by the regenerative converter unit 11 is detected as the charging voltage of the smoothing capacitor 2, that is, the DC voltage Vdc. The voltage automatic adjustment function described above performs adjustment so that the relationship of full-wave rectified voltage Vac × automatic adjustment gain≈DC voltage Vdc is satisfied.

  However, harmonics may be applied to the AC power supply 200 itself from the outside. In this case, as shown in FIG. 4, the waveform is distorted by superimposing the harmonic component on the waveform of the normal AC voltage (dashed line in the figure) (solid line in the figure). For this reason, the charging voltage of the smoothing capacitor 2 is boosted by the voltage amplitude of the harmonic, and the peak value of the AC voltage to which such a harmonic is applied becomes the DC voltage Vdc. On the other hand, the full-wave rectified voltage Vac detected by the AC voltage detector 13 is attenuated by a filter configured by hardware or software existing in the detection system, and the voltage amplitude rise of the AC voltage due to the application of harmonics is accurate. Is not recognized. Therefore, the full-wave rectified voltage Vac is detected to the same extent as the effective value of the full-wave rectified three-phase AC voltage, as in the normal case where no harmonics are applied to the AC power supply 200 itself. The voltage Vdc and the full-wave rectified voltage Vac are greatly different.

  As shown in FIG. 5, even when a harmonic is applied in the middle of a state where the full-wave rectified voltage Vac is normally supplied, the direct current Vdc is gradually boosted after the harmonic is applied, and the full-wave rectified voltage is applied. It is very different from Vac. If the boosted DC voltage Vdc differs from the full-wave rectified voltage Vac by more than the predetermined value, the converter-side power regeneration process start condition is satisfied, and the inverter-side regeneration (1-D) is performed. Even in a non-operational state, there is a possibility that the converter-side power regeneration process is erroneously started.

<2. When harmonics are applied>
Next, an operation sequence when harmonics are applied to AC power supply 200 itself will be described.
(2-A: At start-up) At start-up immediately after the power is turned on, since the full-wave rectified voltage Vac> DC voltage Vdc, the regenerative converter unit 11 rectifies the AC voltage, and the smoothing capacitor 2 is forward charged. However, since harmonics are applied in this case, the DC voltage Vdc is higher than the full-wave rectified voltage Vac detected by the AC voltage detector 13 by the voltage amplitude value of the harmonic component. Even when this harmonic is applied, the AC current Iac naturally flows in the direction from the AC power supply 200 to the power regeneration converter 1 during the initial charging.

  (2-B: Before Motor Driving) The power regeneration converter 1 having the configuration shown in FIG. 1 alone cannot distinguish between the harmonic application state and the non-application state in the AC power source 200. Therefore, the voltage automatic adjustment function distinguishes whether the difference between the DC voltage Vdc and the full-wave rectified voltage Vac is due to the application of harmonics or the regenerative power from the motor driving device 3. Therefore, the automatic initial gain automatic adjustment described in (1-A) above cannot be performed. That is, before the motor is driven, the DC voltage Vdc is maintained higher than the full-wave rectified voltage Vac by the voltage amplitude value of the harmonic component. Before the motor is driven, since the power regeneration converter 1 and the motor drive device 3 are energized, the alternating current Iac is circulated in the direction from the alternating current power supply 200 to the power regeneration converter 1. .

  However, when harmonics are applied (2-C: during motor drive), (2-D: during inverter-side regenerative operation (before converter-side power regeneration process)), and (2-E: converter-side power supply) At the time of regenerative processing, the voltage and current at each location change substantially the same as (1-C), (1-D), and (1-E). FIG. 6 is a time chart showing fluctuations of the full-wave rectified voltage Vac, the DC voltage Vdc, and the flow state of the AC current Iac when harmonics are applied. In FIG. 6, illustration at the time of start-up is omitted, and in order to prioritize the clarification of the illustration, the DC voltage Vdc is shown to greatly decrease compared to the full-wave rectified voltage Vac during motor driving. However, the actual decline is smaller.

  In FIG. 6, in (2-B: before driving the motor), the DC voltage Vdc is higher than the full-wave rectified voltage Vac detected by the AC voltage detection unit 13 by the voltage amplitude value of the harmonic component. The relationship of voltage Vac <DC voltage Vdc is maintained. In (2-C: when driving the motor), the charging power of the smoothing capacitor 2 is consumed for driving the motor, so that the full-wave rectified voltage Vac> the DC voltage Vdc. Then, (2-D: during inverter-side regeneration operation (before converter-side power regeneration processing)), the regenerative power from the three-phase AC motor 300 is accumulated in the smoothing capacitor 2 (reverse charging), and the DC voltage Vdc starts to increase. The full-wave rectified voltage Vac exceeds the full-wave rectified voltage Vac while the direct-current voltage Vdc continues to be boosted, and the relation of full-wave rectified voltage Vac <DC voltage Vdc is established.

  Thereafter, when converter-side power regeneration processing is started by appropriate start determination (2-E: during converter-side power regeneration processing), DC voltage Vdc is stepped down to the vicinity of full-wave rectified voltage Vac, and then full-wave rectified voltage. The relationship of Vac≈DC voltage Vdc is maintained. After the converter-side power regeneration processing is completed, the charging voltage of the smoothing capacitor 2 is increased again by the voltage amplitude value of the harmonic component, and the full-wave rectified voltage Vac <DC voltage Vdc is increased by that amount. The state returns to (2-B: before motor driving). In FIG. 6, the alternating current Iac becomes non-conductive when the full-wave rectified voltage Vac <the direct-current voltage Vdc in the above-described state (2-D: during inverter-side regenerative operation (before the converter-side power regeneration process)). Other than the above, it will be in a distribution state in other states. However, the distribution direction of the above (2-A) (2-B) (2-C) and the above (2-E) is opposite.

  The determination of the start timing of the converter-side power regeneration process is performed by the start determination process performed by the converter regeneration control unit 14. As for this determination, similarly to the case where no harmonics are applied, when the difference between the DC voltage Vdc and the full-wave rectified voltage Vac is simply a predetermined value or more is set as a start condition (2-D ), The converter-side power regeneration process may be erroneously started even in a state other than the inverter-side regeneration operation.

  Therefore, in the present embodiment, when no harmonic is applied to the AC power supply 200 itself due to an external source, the difference between the detected DC voltage Vdc and the full-wave rectified voltage Vac is simply a predetermined value or more. Rather than using a determination condition for the start timing of the converter-side power regeneration process, a new determination condition is set and the converter-side power regeneration process is started.

  Specifically, a reference voltage Vre is newly provided as a voltage value variable that is updated based on the flow state of the AC current Iac, instead of the DC voltage Vdc itself that changes to the same potential as the charging voltage of the smoothing capacitor. The reference voltage Vre is used as a comparison reference voltage, and when the difference between the comparison reference voltage and the DC voltage Vdc is equal to or greater than a predetermined value, it is determined that it is the start timing of converter-side power regeneration processing. Note that in the previous determination conditions, the full-wave rectified voltage Vac corresponds to the comparison reference voltage.

  Basically, the reference voltage Vre is a variable that is updated by sequentially substituting the DC voltage Vdc that changes to the same potential as the charging voltage of the smoothing capacitor. In the example of this embodiment, as a noise countermeasure, the reference voltage Vre is updated by substituting the moving average value of the DC voltage Vdc. However, after the DC voltage Vdc boosted during the inverter-side regeneration operation before the converter-side power regeneration process reaches the full-wave rectified voltage Vac, the updating of the reference voltage Vre is stopped and the previous value is kept. .

  Here, after the DC voltage Vdc boosted during the inverter-side regenerative operation reaches the full-wave rectified voltage Vac, the AC current Iac becomes non-conductive. By using this to detect the start of the AC current Iac non-conduction state, it is possible to detect that the DC voltage Vdc has reached full-wave rectified voltage Vac due to boosting by reverse charging of the inverter side regenerative operation.

  When the DC voltage Vdc and the reference voltage Vre are substantially equal, a determination not to update the reference voltage Vre is also applied.

  In order to make a more reliable start determination, a determination to update the reference voltage Vre is also applied while the DC voltage Vdc is lower than the full-wave rectified voltage Vac even when the DC voltage Vdc and the reference voltage Vre are substantially equal.

In summary,
The reference voltage Vre is basically updated by sequentially substituting the moving average value of the DC voltage Vdc.
-When the alternating current Iac is not in a disconnected state, the updating of the reference voltage Vre is stopped and the previous value is held.
When the reference voltage Vre≈DC voltage Vdc, the update is stopped and the previous value is held.
When the full-wave rectified voltage Vac> the DC voltage Vdc, the reference voltage Vre≈DC voltage Vdc is updated.

  Changes in the reference voltage Vre set in this way are shown in FIGS. 7 and 8 corresponding to FIG. FIG. 7 shows a case where no harmonics are applied, and FIG. 8 shows a case where harmonics are applied. The reference voltage Vre set in this way is basically updated so as to follow the fluctuation of the DC voltage Vdc so as to have substantially the same voltage value. However, the DC voltage Vdc boosted during the inverter side regeneration operation is the full-wave rectified voltage. After reaching Vac, the update is stopped and the previous value is maintained. As described above, during the deceleration control of the motor, while the DC voltage Vdc boosted during the inverter-side regenerative operation exceeds the full-wave rectified voltage Vac, the presence or absence of harmonics applied to the AC power supply 200 is determined. Regardless, the AC current Iac is in a non-conductive state, and the reference voltage Vre is not updated during the non-conductive state. In the example of the present embodiment, the reference voltage Vre updated under such conditions is directly substituted for the comparison reference voltage, and the start timing of the converter-side power regeneration process is determined by comparing the comparison reference voltage with the DC voltage Vdc. .

  Thus, during the operation sequences (1-D) and (2-D), the DC voltage Vdc that continues to be boosted and the reference voltage Vre (= comparison reference voltage) equivalent to the constant full-wave rectified voltage Vac Therefore, when the start condition of Vdc−Vre ≧ predetermined value is satisfied, the start determination process can appropriately determine the start timing of the converter-side power regeneration process. In other operation sequences, since the comparison is made between the DC voltage Vdc and the reference voltage Vre (= comparison reference voltage) that follows and updates the DC voltage Vdc, it starts without satisfying the start condition of Vdc−Vre ≧ predetermined value. The determination process does not erroneously start the converter-side power regeneration process.

  Next, the start determination process of the converter-side power regeneration process executed by a CPU (not shown) provided in the converter regeneration control unit 14 will be described using the flowchart of FIG. This flow is started when the power regeneration converter 1 is powered on.

  First, in step S5, the full-wave rectified voltage Vac via the AC voltage detector 13 and the DC voltage Vdc from the DC bus are detected.

  Then, the process proceeds to step S <b> 10, and the alternating current Iac is detected via the alternating current detection unit 12. This procedure corresponds to the AC current detection step described in each claim.

  Then, the process proceeds to step S15, and it is determined whether or not the alternating current Iac is in a circulating state as detected in step S10. If the alternating current Iac is not detected to such an extent that the alternating current Iac is recognized as being in a circulating state, the determination is not satisfied and the routine goes to Step S20. In this case, the DC voltage Vdc being boosted during the inverter-side regeneration operation (before the converter-side power regeneration process) exceeds the full-wave rectified voltage Vac, or otherwise there is no need to update the reference voltage Vre, for example ( 1-B: Before driving the motor) or (2-B) or the like, it can be considered that the DC voltage Vdc is kept constant.

  In step S20, the reference voltage Vre is not updated, and the process proceeds to step S45 described later while maintaining the previous value.

  On the other hand, if it is determined in step S15 that the alternating current Iac is detected to such an extent that the alternating current Iac is recognized as being in a circulating state, the determination is satisfied, and the routine goes to step S25.

  In step S25, the full-wave rectified voltage Vac detected in step S5 is compared with the DC voltage Vdc to determine whether or not the DC voltage Vdc is lower than the full-wave rectified voltage Vac. If the DC voltage Vdc is lower than the full-wave rectified voltage Vac, the determination is satisfied, and the routine goes to Step S35.

  On the other hand, if the DC voltage Vdc is equal to or higher than the full-wave rectified voltage Vac, the determination is not satisfied, and the routine goes to Step S30.

  In step S30, the DC voltage Vdc detected in step S5 is compared with the reference voltage Vre to determine whether the DC voltage Vdc and the reference voltage Vre are substantially equal. If the DC voltage Vdc and the reference voltage Vre are substantially equal within a predetermined error, the determination is satisfied, and the routine goes to Step S20. In this case, it can be considered that there is no change in the DC voltage Vdc, and it is not necessary to update the reference voltage Vre.

  On the other hand, if the DC voltage Vdc and the reference voltage Vre are different from each other by a predetermined error or more, the determination is not satisfied, and the routine goes to Step S35. In this case, it can be considered that the DC voltage Vdc is changing and the reference voltage Vre needs to be updated accordingly.

  In step S35, a moving average of the DC voltage Vdc detected at a predetermined number of times in the latest past is calculated. Thereby, the noise contained in the fluctuation | variation of DC voltage Vdc can be planarized.

  Then, the process proceeds to step S40, where the moving average of the DC voltage Vdc calculated in step S35 is substituted for the reference voltage Vre and updated. Thereby, the reference voltage Vre can be updated so as to follow the fluctuation of the DC voltage Vdc.

  Then, the process proceeds to step S45, and it is determined whether or not a deviation obtained by subtracting the reference voltage Vre (= comparison reference voltage) obtained in step S40 from the DC voltage Vdc detected in step S5 is equal to or larger than a predetermined value. If the deviation is equal to or greater than the predetermined value, the determination is satisfied, and the routine goes to Step S100.

  In step S100, an appropriate gate signal is output to each arm switching element 51 provided in the regenerative converter unit 11, and converter-side power regeneration processing by a 120 ° energization method is executed. And it returns to step S5 and repeats the same procedure. The procedure of step S100 corresponds to the converter regeneration control step described in each claim.

  On the other hand, if the deviation is smaller than the predetermined value in the determination in step S50, the determination is not satisfied and the process returns to step S5 and the same procedure is repeated.

  In the determinations in step S15, step S25, and step S30, the determination is performed three times in succession including the detection in steps S5 and S10, respectively, and the update condition is satisfied three times. Only the reference voltage Vre after step S35 may be updated.

  As described above, according to the motor drive system 100 of the present embodiment, the AC power supply 200 is operated in the operation sequence of (1-D: inverter side regenerative operation (before converter side power regeneration process)) and (2-D). The converter side power regeneration process start determination process is performed by utilizing the fact that the distribution state of the alternating current Iac is interrupted regardless of the presence or absence of harmonics applied to. That is, the converter regeneration control unit 14 performs the converter-side power regeneration process at the start timing determined by the start determination process based on the alternating current flow state detected by the alternating current detection unit 12.

  As a result, the motor drive system 100 of the present embodiment has a motor drive apparatus 3 that substantially requires converter-side power regeneration processing of the power regeneration converter 1 regardless of the presence or absence of harmonics applied to the AC power supply 200. In the period during the inverter side regeneration operation, the start determination process can appropriately determine the start timing of the converter side power regeneration process. As a result, the power regeneration process can be performed at an appropriate start timing regardless of the presence or absence of harmonics applied to the AC power supply 200.

  In this embodiment, in particular, the start determination process performed by the converter regeneration control unit 14 is updated not based on the value of the full-wave rectified voltage Vac but based on a change in the alternating current flow state and a change in the direct current voltage Vdc. The value of the reference voltage Vre as the voltage value variable set to is set as a comparison reference voltage, and this is compared with the DC voltage Vdc. Then, when the DC voltage Vdc becomes larger than the comparison reference voltage by a predetermined value or more, it is determined that it is the start timing of the converter-side power regeneration process. Thus, the DC voltage Vdc boosted during the inverter-side regeneration operation in the operation sequence of (1-D: inverter-side regeneration operation (before the converter-side power regeneration process)) and (2-D) is changed to the full-wave rectified voltage Vac. When exceeded, it is possible to perform the start determination process for the converter-side power regeneration process using the fact that the distribution state of the alternating current Iac is disabled regardless of the presence or absence of harmonics applied to the alternating current power supply 200.

  In this embodiment, in particular, the reference voltage Vre is basically updated so as to follow the fluctuation of the DC voltage Vdc and become the same voltage value. However, the inverter side regeneration is performed for a while after the disconnection state of the alternating current Iac is detected, that is, (1-D: inverter side regeneration operation (before converter side power regeneration process)) and (2-D). During the operation, the reference voltage Vre is maintained substantially equal to the full-wave rectified voltage Vac for a while after the DC voltage Vdc being boosted reaches the full-wave rectified voltage Vac. This is because there is no harmonic applied to the AC power supply 200 after the DC voltage Vdc exceeds the full-wave rectified voltage Vac during the inverter-side regenerative operation in the operation sequences (1-D) and (2-D). This is because the reference voltage Vre is not updated while the AC current Iac is in a non-conductive state and the non-conductive state is detected. As a result, the DC voltage Vdc boosted during the inverter side regenerative operation is maintained substantially equal to the full-wave rectified voltage Vac for a while after reaching the full-wave rectified voltage Vac.

  Further, during the inverter side regenerative operation, the DC voltage Vdc rises over time even after reaching the full-wave rectified voltage Vac. Therefore, the start determination process compares the rising DC voltage Vdc at this time with the comparison reference voltage that is maintained substantially equal to the full-wave rectified voltage Vac, and the DC voltage Vdc is greater than or equal to a predetermined value from the comparison reference voltage. When it becomes large, it determines with it being the timing which starts the converter side power supply regeneration process of the regeneration converter part 11. FIG. In this way, when the DC voltage Vdc boosted during the inverter-side regenerative operation in the operation sequences (1-D) and (2-D) exceeds the full-wave rectified voltage Vac, it is applied to the AC power supply 200. Regardless of the presence or absence of harmonics, the start determination process using the fact that the distribution state of the alternating current Iac is interrupted becomes possible.

  On the other hand, in the operation sequence (1-B: before motor driving) and (2-B) in which there is no operation of the three-phase AC motor 300 by the drive control of the motor driving device 3, the reference voltage Vre is as described above. Following the variation of the DC voltage Vdc, the same voltage value is maintained, that is, the comparison reference voltage and the DC voltage Vdc become equal. Thus, even when the start determination process continues to compare the DC voltage Vdc and the comparison reference voltage, the converter-side power regeneration of the regenerative converter unit 11 is performed regardless of the presence or absence of harmonics applied to the AC power supply 200 before driving the motor. The erroneous determination of the process start timing is eliminated. As a result, even if the start determination process always performs the same comparison determination, the start timing of the converter-side power regeneration process can be appropriately determined regardless of the presence or absence of harmonics applied to the AC power supply 200.

  In this embodiment, particularly, the reference voltage Vre is updated by substituting the moving average value of the DC voltage Vdc, so that the influence of noise due to the harmonics applied to the AC power supply 200 affects the update of the reference voltage Vre. Can be suppressed.

  In this embodiment, in particular, in the operation sequence (1-B: before motor driving) and (2-B), the DC voltage Vdc does not vary, and the reference voltage Ver and the DC voltage Vdc are substantially equal. Does not update the reference voltage Vre. Thereby, like the above, it can suppress that the influence of the noise by the harmonic applied to AC power supply 200 reaches update of reference voltage Vre.

  In this embodiment, in particular, when the DC voltage Vdc is lower than the full-wave rectified voltage Vac in the operation sequence (1-C: when driving the motor) and (2-C), the reference voltage Vre and the DC Even when the voltage Vdc is substantially equal, the reference voltage Vre is updated. Thus, for example, even when the DC voltage Vdc is slightly lower than the full-wave rectified voltage Vac during low load operation of the three-phase AC motor 300, (1-D: inverter side regeneration operation (converter side power regeneration) Before the processing))) and (2-D), after the inverter unit 31 starts the inverter-side regenerative operation, when the DC voltage Vdc to be boosted reaches the full-wave rectified voltage Vac, the comparison reference voltage is completely set. It can be made substantially equal to the wave rectified voltage Vac. In particular, when the moving average value of the DC voltage Vdc described above is updated by substituting it into the reference voltage Vre, an overvoltage associated with a sudden inverter-side regenerative operation is compensated for by compensating for a delay element due to the calculation of the moving average value. The effect is great because it is possible to avoid the occurrence of

  In the above embodiment, the value of the reference voltage Vre is directly substituted for the comparison reference voltage. However, the present invention is not limited to this. In addition, one of the reference voltage Vre updated as described above and the full-wave rectified voltage Vac, whichever is larger, is substituted into the comparison reference voltage, and the comparison between the reference voltage Vre and the DC voltage Vdc allows the converter-side power regeneration processing. The start timing may be determined. The comparison reference voltage set in this way is also basically updated to follow the fluctuation of the DC voltage Vdc so as to have substantially the same voltage value, but the full-wave rectified voltage Vac is obtained during motor driving and motor deceleration control. Is continuously maintained (not shown in particular). In this case, in the operation sequences (1-C: when the motor is driven) and (2-C), the comparison reference voltage is the full-wave rectified voltage Vac, and during this time, the relationship between the full-wave rectified voltage Vac> the DC voltage Vdc is satisfied. Therefore, the start condition (Vdc−Vx ≧ predetermined value) is not satisfied, and the start timing is not erroneously determined.

  When the comparison reference voltage is set in this way, a procedure for substituting the larger one of the reference voltage Vre and the full-wave rectified voltage Vac into the comparison reference voltage Vx immediately before step S45 in the flow of FIG. And “Vdc−Vx ≧ predetermined value” may be determined in the determination in step S45. When the comparison reference voltage is set in this way, it is particularly useful for avoiding erroneous determination of the start determination process at the time of initial charging of (1-A: startup) and (2-A).

  In addition, since the effect by the above this embodiment can be implement | achieved only by changing a start condition in the start determination process which the converter regeneration control part 14 performs, there is no influence on another process. Such resistance to the application of external harmonics is very effective as a measure for EMS evaluation in the EMC directive.

  In the above-described embodiment, the rotary three-phase AC motor 300 is a driving target. However, the driving type is not limited to this, and a direct-acting motor can also be applied to the driving target.

  In addition to those already described above, the methods according to the above-described embodiments and modifications may be used in appropriate combination.

  In addition, although not illustrated one by one, the present invention is implemented with various modifications within a range not departing from the gist thereof.

DESCRIPTION OF SYMBOLS 1 Power supply regenerative converter 2 Smoothing capacitor 3 Motor drive device 11 Regenerative converter part 11a Rectification bridge circuit 11b Regenerative switching circuit 12 AC current detection part 13 AC voltage detection part 14 Converter regeneration control part 31 Inverter part 31a Regenerative bridge circuit 31b Drive switching circuit 32 Inverter controller 51, 61 Arm switching element (semiconductor switching element)
52, 62 Diode 100 Motor drive system 200 External AC power supply 300 Three-phase AC motor Iac AC current Vac AC voltage Vdc DC current Vre Reference voltage, comparison reference voltage

Claims (9)

An alternating current detection unit for detecting the alternating current flow state of each phase of the input alternating current power supply;
A regenerative switching unit in which a rectifier bridge circuit that rectifies the AC power supply in full wave and outputs a DC voltage and a set of two semiconductor switching elements connected in series are connected in parallel corresponding to each phase of the rectifier bridge circuit And a regenerative converter unit,
A smoothing capacitor for smoothing the DC voltage;
At the start timing determined by the start determination process based on the AC current flow state detected by the AC current detection unit, the semiconductor switching elements of the regenerative converter unit are respectively switched, and the regenerative power generated on the DC voltage side is A converter regeneration control unit that performs power regeneration processing so as to return to the AC power supply;
A power regeneration converter comprising: An AC voltage detector that detects the full-wave rectified voltage by full-wave rectifying the AC input voltage from the AC power supply;
The start determination process performed by the converter regeneration control unit is:
The reference voltage updated based on the alternating current flow state and the direct current voltage is set as a comparison reference voltage,
2. The power regeneration converter according to claim 1, wherein the power regeneration regeneration is determined to be a start timing of the power regeneration processing when the DC voltage becomes greater than a predetermined value from the comparison reference voltage. An AC voltage detector that detects the full-wave rectified voltage by full-wave rectifying the AC input voltage from the AC power supply;
The start determination process performed by the converter regeneration control unit is:
The reference voltage that is updated based on the alternating current flow state and the direct current voltage, and the full-wave rectified voltage detected by the alternating voltage detection unit, whichever is larger, is used as a comparison reference voltage,
2. The power regeneration converter according to claim 1, wherein the power regeneration regeneration is determined to be a start timing of the power regeneration processing when the DC voltage becomes greater than a predetermined value from the comparison reference voltage.   The start determination process performed by the converter regeneration control unit is performed by sequentially substituting the DC voltage into the reference voltage and updating the reference voltage, and the reference voltage is not updated while the AC current flowing state is a non-conductive state. The power regeneration converter according to claim 2 or 3.   The power regeneration converter according to claim 4, wherein the start determination process performed by the converter regeneration control unit is updated by substituting a moving average of the DC voltage into the reference voltage.   6. The power regeneration converter according to claim 4, wherein the start determination process performed by the converter regeneration control unit does not update the reference voltage when the reference voltage and the DC voltage are substantially equal.   The power regeneration converter according to claim 6, wherein the start determination process performed by the converter regeneration control unit is updated when the DC voltage is lower than the full-wave rectified voltage. An alternating current detection unit for detecting the alternating current flow state of each phase of the input alternating current power supply;
A regenerative switching unit in which a rectifier bridge circuit that rectifies the AC power supply in full wave and outputs a DC voltage and a set of two semiconductor switching elements connected in series are connected in parallel corresponding to each phase of the rectifier bridge circuit And a regenerative converter unit,
A smoothing capacitor for smoothing the DC voltage;
At the start timing determined by the start determination process based on the AC current flow state detected by the AC current detection unit, the semiconductor switching elements of the regenerative converter unit are respectively switched, and the regenerative power generated on the DC voltage side is A converter regeneration control unit that performs power regeneration processing so as to return to the AC power supply;
An inverter connected to the smoothing capacitor;
An inverter control unit that PWM-controls the inverter unit so as to supply desired power to a motor connected to the inverter unit based on a motor control command from a host controller;
A motor drive system comprising: A rectifier bridge circuit that outputs a DC voltage by full-wave rectifying the input AC power source and a pair of two semiconductor switching elements connected in series are connected in parallel corresponding to each phase of the rectifier bridge circuit. A power supply regeneration processing method to be executed for a regenerative converter unit having a switching unit,
An alternating current detection step for detecting an alternating current flow state of each phase of the alternating current power supply;
At the start timing determined in the start determination process based on the alternating current flow state detected in the alternating current detection step, the semiconductor switching elements of the regenerative converter unit are respectively switched, and the regenerative power generated on the DC voltage side is A converter regeneration control step for performing a power regeneration process so as to return to the AC power supply;
The power regeneration processing method characterized by performing.

Images