JP2008253060A - Power supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply device capable of preventing the stop of a load connected to the power supply device, even if zero cross interruption pulse an PAM interruption pulse are generated. <P>SOLUTION: The power supply device converts AC power into DC power, and supplies the DC power to a load (40). The power supply device includes a control section, a rectifying circuit (10), a smoothing circuit (20) and a switch (SW). The control section sets not less than a first time minimally required for calculation of a current value of AC current between the zero cross interruption pulse and the PAM interruption pulse. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power supply device, and more particularly to a power supply device that performs PAM control.

  Some air conditioners (air conditioners) that perform cooling and heating change the operating frequency of the compressor when adjusting the cooling and heating capacity. In such an air conditioner, the rotation speed of a motor that drives the compressor is controlled by inverter control.

  Some power supply devices that perform inverter control perform PAM (Pulse Amplitude Modulation) control. In PAM control, an AC voltage is converted to a DC voltage by a rectifier circuit, and then converted to a desired voltage by a booster circuit. The booster circuit includes a reactor element, a switching element, a diode, a capacitor, and the like.

  In the booster circuit, by controlling the on-time ratio (duty ratio) of the switching element, the waveform and current value of the AC input current input to the rectifier circuit in the previous stage can be controlled. Power factor improvement and harmonic current reduction are possible.

  Note that by generating at least two or more PAM pulses in a half cycle of the power supply frequency (by increasing the number of pulses), power factor improvement and harmonic current can be further reduced. This PAM control is referred to as multi-pulse PAM control.

  On the other hand, in order to generate a PAM waveform for PAM control, it is necessary to generate a PAM interrupt pulse used for ON / OFF switching of the PAM waveform. Further, in order to generate the PAM interrupt pulse, it is necessary to generate a zero cross interrupt pulse indicating detection of a zero cross point of AC power (a point of the AC power waveform at a voltage of 0 V).

  Here, for example, Patent Document 1 exists as a power supply device that performs PAM control.

Japanese Patent Laid-Open No. 10-337031

  As described above, in the configuration in which the PAM interrupt pulse and the zero-cross interrupt pulse are generated by the control unit in the power supply device, the control unit calculates the current value flowing through the load (compressor motor) connected to the output side of the power supply device When doing so, the following problems may occur.

  Generally, the priority of generation of the PAM interrupt pulse and the zero-cross interrupt pulse in the control unit is higher than the priority of calculation of the current value in the control unit. Therefore, if the generation interrupt of each pulse is input while calculating the current value flowing through the load in the control unit, the calculation of the current value needs to wait until the generation interrupt of each pulse ends. On the other hand, when the waiting time for the calculation of the current value in the control unit becomes longer, the load operation stops. Therefore, from the viewpoint of stopping the load operation, the waiting time for calculating the current value is determined to be within a predetermined time.

  Therefore, in the configuration of the power supply apparatus, when generation (rising) of the PAM interrupt pulse is started after a lapse of a minute time (including zero) after the falling of the zero cross interrupt pulse, the calculation time of the current value in the control unit is started. The waiting time becomes longer, and the problem that the load stops as described above may occur.

  Accordingly, an object of the present invention is to provide a power supply device that can prevent a load connected to the power supply device from being stopped even if a zero-cross interrupt pulse and a PAM interrupt pulse are generated.

  In order to achieve the above object, a power supply device according to claim 1 according to the present invention is a power supply device that converts AC power into DC power and supplies the DC power to a load (40). And a first capacitor (2) and a second capacitor (3) connected in series. The output from the rectifier circuit is smoothed to generate the DC power. A switch (SW) disposed between a smoothing circuit (20) for output, the rectifier circuit, and a connection point (N1) between the first capacitor and the second capacitor; Used to calculate the current value of the DC current supplied to the load, generate a zero-cross interrupt pulse representing the detection of the zero-cross point of the AC power input to the rectifier circuit, and generate a PAM waveform. input And a control unit that generates a PAM interrupt pulse. The generation timing of the PAM interrupt pulse after the generation of the zero cross interrupt pulse varies dynamically, and the control unit includes the zero cross interrupt pulse. And the PAM interrupt pulse are provided at least for the first time necessary for the calculation of the current value of the direct current.

  The power supply device according to claim 2 of the present invention is the power supply device according to claim 1, wherein the control unit generates the PAM interrupt pulse after the falling edge of the zero-cross interrupt pulse. A second time until the second time is longer than the first time, the control unit, after the falling edge of the zero-cross interrupt pulse, After the elapse of time, the PAM interrupt pulse is generated.

  Further, the power supply device according to claim 3 according to the present invention is the power supply device according to claim 1 or 2, wherein the control unit performs the PAM interrupt pulse after the falling edge of the zero-cross interrupt pulse. Can be calculated, and if the second time is less than or equal to the first time, the control unit, after falling of the zero-cross interrupt pulse, After the first time has elapsed, the PAM interrupt pulse is generated.

  In the power supply device according to the first aspect of the present invention, the control unit is provided between the zero-cross interrupt pulse and the PAM interrupt pulse for a minimum of the first time necessary for calculating the current value of the direct current.

  Accordingly, for example, immediately before the zero-cross interrupt pulse rises or until the generation (rise) of the next PAM interrupt pulse starts after the zero-cross interrupt pulse falls, the control unit causes the compressor motor (load) 40 to flow. Even if the calculation of the current value is started, after the falling edge of the zero cross interrupt pulse, the time of the first time is secured at least. Therefore, it is possible to prevent the waiting time for the calculation of the current value in the control unit from being prolonged. Thereby, it is possible to prevent the operation of the load connected to the power supply device from stopping due to the long calculation of the current value.

  In the power supply device according to claim 2 of the present invention, the control unit can calculate a second time from when the zero-cross interrupt pulse falls until the PAM interrupt pulse is generated. When the time is longer than the first time, the control unit generates a PAM interrupt pulse after the second time elapses after the falling edge of the zero-cross interrupt pulse.

  Therefore, by determining the generation timing of the PAM interrupt pulse after the falling of the zero cross interrupt pulse based on the second time calculated in the control unit, it is possible to secure a time longer than the first time as the period between the pulses. . Therefore, the effect described in claim 1 can be obtained.

  In the power supply device according to claim 3 of the present invention, the control unit can calculate a second time from when the zero cross interrupt pulse falls to when the PAM interrupt pulse is generated. When the time is equal to or shorter than the first time, the control unit generates a PAM interrupt pulse after the first time has elapsed after the falling edge of the zero-cross interrupt pulse.

  Therefore, even if the second time (≦ first time) until the generation of the PAM interrupt pulse after the falling edge of the zero cross interrupt pulse is calculated in the control unit, the first time is secured as the period between the pulses. it can. Therefore, the effect described in claim 1 can be obtained.

  Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.

<Embodiment>
An air conditioner (hereinafter referred to as “air conditioner”) includes an indoor unit and an outdoor unit, and the indoor unit and the outdoor unit are connected via a refrigerant pipe that circulates a refrigerant.

  In the air conditioner, when the compressor is operated by the rotational drive of the compressor motor, the refrigerant is circulated in the refrigerant pipe. In the cooling mode, the refrigerant compressed by the compressor is liquefied by being supplied to the heat exchanger, and the liquefied refrigerant is vaporized by the heat exchanger of the indoor unit, thereby cooling the air passing through the heat exchanger. To do. On the other hand, in the heating mode, the refrigerant compressed by the compressor dissipates heat by being condensed by the heat exchanger of the indoor unit, and the air passing through the heat exchanger is heated by the heat dissipated by the refrigerant.

  The outdoor unit is provided with the power supply device shown in FIG. 1 and a control unit (not shown) disposed in the power supply device. The power supply device converts the AC power supply 7 into DC power for driving the compressor motor 40. Further, the control unit controls the operation of the outdoor unit and the operation of the power supply device.

  As shown in FIG. 1, the power supply device includes a rectifier circuit 10, a smoothing circuit 20, an inverter circuit 30, and a switch SW. Furthermore, the power supply apparatus also includes a control unit not shown in FIG. The power supply device converts AC power supplied from the AC power supply 7 into DC power having a predetermined voltage, and outputs (supplies) the DC power to the compressor motor (which can be grasped as a load) 40 via the inverter circuit 30. .

  The inverter circuit 30 has a general configuration in which a switching element is provided. The inverter circuit 30 outputs DC power corresponding to the switching operation to the compressor motor 40 by the on / off control of the switching element. Note that the compressor motor 40 is driven to rotate at a rotational speed corresponding to the output power (voltage).

  As shown in FIG. 2, the switch SW repeats the switching operation a plurality of times, thereby generating a PAM waveform having at least two or more PAM pulses within a half cycle of the AC voltage V (referred to as a multi-pulse PAM). By generating the multi-pulse PAM, harmonics in the current I flowing through the rectifier circuit 10 can be further suppressed.

  On the other hand, the rectifier circuit 10 is configured by connecting a plurality of diodes 1 in a bridge shape. An AC power supply 7 is connected to the input portion of the rectifier circuit 10. The rectifier circuit 10 is a circuit for rectifying the AC power supply 7. Further, the smoothing circuit 20 is connected to the output portion of the rectifier circuit 10.

  The smoothing circuit 20 includes capacitors connected in series (can be understood as a first capacitor and a second capacitor) 2 and 3, and capacitors connected in parallel to these capacitors 2 and 3 (can be understood as a third capacitor). 4. The smoothing circuit 20 smoothes the pulsating current output from the rectifying circuit 10 and outputs DC power. Thereby, the voltage doubler wave rectifier circuit is formed by the rectifier circuit 10 and the smoothing circuit 20.

  A switch SW is disposed between the rectifier circuit 10 and the smoothing circuit 20. More specifically, the switch SW is disposed between the rectifier circuit 10 and the connection point N <b> 1 between the first capacitor 2 and the second capacitor 3. The switch SW is on / off controlled by high-frequency interrupt pulses output from the control unit.

  On the other hand, input power detection means is connected to the control unit. The control unit reads the phase signal of the waveform of the input voltage together with the AC voltage (input voltage) from the AC power source 7 by the input power detection means. Then, the zero cross point at which the waveform of the AC power supply voltage switches from plus to minus (minus to plus) is detected from the read phase signal. The control unit calculates the timing for outputting the PAM interrupt pulse based on the zero cross point.

  Next, PAM control will be described with reference to FIG. FIG. 3 is a timing chart for explaining the PAM control.

  Here, from the upper stage to the lower stage of FIG. 3, the AC power (AC voltage) waveform input from the AC power supply 7 to the power supply device, the PAM waveform (can also be understood as the ON / OFF waveform of the switch SW), and the PAM interrupt pulse (hatch pulse). ) And zero-cross interrupt pulses (plain pulses) are depicted.

  The control unit generates a zero cross interrupt pulse indicating the detection of the zero cross point of the AC voltage. Then, the control unit generates a plurality of PAM interrupt pulses at a timing calculated in advance based on the zero-cross interrupt pulse. In order to generate a plurality of PAM pulses in a half cycle of the AC voltage, a plurality of PAM interrupt pulses are continuously generated (this is referred to as multi-pulse PAM control).

  Each PAM interrupt pulse generated as described above is input to the switch SW. Thereby, the switch SW repeats the ON / OFF operation shown in FIG. A waveform indicating the ON / OFF repetition is a PAM waveform. Each pulse constituting the PAM waveform is a PAM pulse.

  By generating the PAM waveform as described above, the harmonic current can be suppressed as described with reference to FIG.

  Note that the generation timing of the PAM interrupt pulse after the generation of the zero-cross interrupt pulse varies dynamically. For example, at a certain time t1, the phase (time) from the generation of the zero-cross interrupt pulse to the generation of the PAM interrupt pulse is T1, and at another time t2, the generation from the generation of the zero-cross interrupt pulse to the generation of the PAM interrupt pulse is performed. The phase (time) can be T2 (≠ T1).

  In the control unit, a maximum phase value and a minimum phase value (which can be grasped as the first time) are determined in advance.

  The maximum phase value is the maximum allowable phase (time) from the fall of the zero-cross interrupt pulse until the next PAM interrupt pulse is generated. The maximum allowable phase (time) is determined from the viewpoint of shaping the PAM waveform. On the other hand, the minimum phase value is the minimum allowable phase (can be grasped as the first time) from the falling edge of the zero-cross interrupt pulse until the next PAM interrupt pulse is generated. The minimum allowable phase is the minimum time required for the control unit to calculate the current value of the direct current supplied to the compressor motor 40.

  As can be seen from the above description, the control unit calculates the current value of the direct current supplied to the compressor motor 40. In addition, the control unit generates a zero-cross interrupt pulse that represents detection of a zero-cross point of AC power input to the rectifier circuit 10. Further, the control unit is used when generating a PAM waveform, and generates a PAM interrupt pulse to be input to the switch.

  Next, the operation of the power supply device (control unit) according to the present invention will be described.

  First, the control unit calculates a time (phase) ph after the falling edge of the zero cross interrupt pulse until the next generation of the PAM interrupt pulse. The calculated time ph can be grasped as the second time. Thereafter, the control unit compares the maximum phase value set in advance with the calculated time ph.

  When the time ph is equal to or greater than the maximum phase value, the control unit generates the next PAM interrupt pulse after the maximum phase value has elapsed after the falling edge of the zero-cross interrupt pulse. That is, the control unit generates the next PAM interrupt pulse after the falling edge of the zero cross interrupt pulse by using the maximum phase value without using the time ph calculated in advance.

  On the other hand, when the time ph is less than the maximum phase value, the control unit performs the following comparison process. That is, the control unit compares the preset minimum phase value with the calculated time ph.

  When the time ph is longer than the minimum phase value, the control unit generates the next PAM interrupt pulse after the time ph has elapsed after the falling edge of the zero-cross interrupt pulse.

  On the other hand, when the time ph is equal to or less than the minimum phase value, the control unit generates the next PAM interrupt pulse after the minimum phase value has elapsed after the falling edge of the zero-cross interrupt pulse. That is, the control unit generates the next PAM interrupt pulse after the falling edge of the zero cross interrupt pulse by using the minimum phase value without using the time ph calculated in advance.

  As can be seen from the above processing, by applying the power supply device according to the present invention, at least the minimum phase value is secured from the falling edge of the zero-cross interrupt pulse to the generation of the next PAM interrupt pulse. In other words, after the falling edge of the zero-cross interrupt pulse, the control unit waits for the next PAM interrupt pulse after the minimum time (can be grasped as the first time) necessary for calculation of the current value of the direct current in the control unit. Generate.

  The maximum phase value is used to define (limit) the maximum time from the falling edge of the zero-cross interrupt pulse until the next PAM interrupt pulse is generated from the viewpoint of waveform shaping of the PAM waveform. It is. Therefore, the following effects can be obtained without limiting the time from the falling edge of the zero-cross interrupt pulse to the generation of the next PAM interrupt pulse.

  As described above, in the power supply device according to the present invention, the generation timing of the PAM interrupt pulse after the generation of the zero-cross interrupt pulse varies dynamically. A PAM interrupt pulse is generated after the minimum time (first time) required for the calculation of the current value of the direct current in the control unit has elapsed.

  More specifically, the control unit calculates in advance the time (second time) ph from the falling edge of the zero-crossing interrupt pulse until the PAM interrupt pulse is generated, and the time ph is the phase minimum value (first time) If it is longer than (time), the control unit generates a PAM interrupt pulse after the second time elapses after the falling edge of the zero-cross interrupt pulse. On the other hand, when the time ph is equal to or smaller than the phase minimum value, the control unit generates a PAM interrupt pulse after the phase minimum value elapses after the falling edge of the zero-cross interrupt pulse.

  Accordingly, for example, immediately before the rising edge of the zero-cross interrupt pulse or until the generation (rise) of the next PAM interrupt pulse is started after the falling edge of the zero-cross interrupt pulse, the control unit causes the compressor motor (load) 40 to flow. Even when the calculation of the current value is started, after the falling edge of the zero-cross interrupt pulse, a time of at least the phase minimum value (first time) is secured.

  Therefore, it is possible to prevent the waiting time for the calculation of the current value in the control unit from being prolonged. Thereby, it can also prevent that the operation | movement of the compressor motor (load) 40 connected to a power supply device stops because calculation of the said current value becomes long.

  In the above, after the falling edge of the zero-cross interrupt pulse, the PAM interrupt occurs after the minimum time necessary for calculating the current value of the DC current in the control unit (the minimum phase value can be grasped as the first time). A pulse was generated.

  However, after the fall of the PAM interrupt pulse just before the occurrence of the zero-cross interrupt pulse, after the elapse of more than the time necessary for calculating the current value of the DC current in the control unit (minimum phase value and can be grasped as the first time) A technique for generating the zero-cross interrupt pulse may be used in combination.

It is a circuit diagram which shows the structure of a power supply device. It is a figure which shows the mode of PAM control. It is a figure for demonstrating PAM control.

Explanation of symbols

1 Diode 2, 3, 4 Capacitor 7 AC Power Supply 10 Rectifier Circuit 20 Smoothing Circuit 30 Inverter Circuit 40 Compressor Motor

Claims (3)

In a power supply device that converts AC power into DC power and supplies the DC power to a load (40),
A rectifier circuit (10) for rectifying the AC power;
A smoothing circuit (20) which is composed of a first capacitor (2) and a second capacitor (3) connected in series, which smooths the output from the rectifier circuit and outputs the DC power;
A switch (SW) disposed between the rectifier circuit and a connection point (N1) between the first capacitor and the second capacitor;
The switch is used for calculation of a current value of a direct current supplied to the load, generation of a zero-cross interrupt pulse representing detection of a zero-cross point of the AC power input to the rectifier circuit, and generation of a PAM waveform, A control unit for generating a PAM interrupt pulse to be input to
The generation time of the PAM interrupt pulse after the generation of the zero-cross interrupt pulse varies dynamically,
The controller is
Between the zero-cross interrupt pulse and the PAM interrupt pulse, a minimum time required for calculation of the current value of the DC current is provided for a first time or more.
A power supply device characterized by that. The controller is
A second time from the falling edge of the zero cross interrupt pulse to the generation of the PAM interrupt pulse can be calculated;
If the second time is longer than the first time,
The controller is
Generating the PAM interrupt pulse after the second time has elapsed after falling of the zero-cross interrupt pulse;
The power supply device according to claim 1. The controller is
A second time from the falling edge of the zero cross interrupt pulse to the generation of the PAM interrupt pulse can be calculated;
If the second time is less than or equal to the first time,
The controller is
Generating the PAM interrupt pulse after the first time has elapsed after falling of the zero-cross interrupt pulse;
The power supply device according to claim 1, wherein the power supply device is provided.

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