JP5286309B2 - Power supply circuit and control circuit thereof - Google Patents

Description

  The present invention relates to a method for controlling a power factor correction circuit or a harmonic current suppression circuit of a single-phase AC power supply, and a motor driving device and an air conditioner using the same.

  Power supply circuits that improve the power factor of single-phase AC power supplies or suppress harmonic currents are widely used. Among them, the power supply circuit using the step-up chopper circuit composed of the reactor, the switching element, and the diode has a simple circuit configuration and control configuration, so that an inverter control device or the like (inverter air conditioner or the like) that does not require regeneration to the power source is used. Used as a power circuit.

  A number of power factor improvement methods or harmonic current suppression methods using a boost chopper circuit have been reported. In particular, Patent Document 1 controls an input current waveform to a sine wave waveform synchronized with a power supply voltage using only a power supply current instantaneous value and a proportional gain without detecting a reference sine wave current command waveform and a power supply phase. A system (this is called a basic system) is described. Patent Document 2 describes the contents of applying the above technique.

  Patent Document 2 proposes a constant boost ratio control system (partial switching system) that stops the switching operation near the peak of the input current for the purpose of increasing the efficiency of the boost chopper circuit.

  The Patent Document 1 is described on the premise that the switching operation (global switching method) is performed in the entire power supply cycle. However, in this global switching method, the switching loss increases and the circuit efficiency decreases. Therefore, the constant boost ratio control method described in Patent Document 2 stops the switching operation near the peak of the power supply current while following the concept of the above basic method (not detecting the reference sine wave current command waveform or power supply phase). A partial switching system is used to reduce switching loss.

  The invention disclosed in Patent Document 2 is a method of partial switching without detecting a reference sine wave current command waveform or power supply phase, and is an excellent control method. However, the step-up ratio is set constant. Therefore, the DC voltage changes according to the power supply voltage and the load connected to the power supply circuit.

  Here, as an example of controlling a DC voltage in a power supply circuit using a step-up chopper circuit, Patent Documents 3 to 7 and the like have been proposed, but these are methods using a whole area switching method, and reducing switching loss. And stable control of DC voltage are not considered.

Japanese Patent Laid-Open No. 1-114372 Japanese Patent No. 2796340 JP 2003-289696 A JP 2000-350442 A JP 09-149690 A Japanese Patent Laid-Open No. 2003-189689 Japanese Patent Laid-Open No. 2001-231262

  The above-described change in DC voltage is an indispensable phenomenon for partial switching, and is also a feature (advantage) of this method, but when the power supply voltage or load changes greatly, the DC voltage also changes greatly, There is a possibility that the operation of a system to which this method (power supply circuit) is applied cannot be maintained. For example, when applied to a compressor drive motor drive device for an inverter air conditioner, once the motor drive stops, the system stops for a certain period of time to balance the compressor load, reducing the capacity of the air conditioner. There is a risk.

  As described above, the problem to be solved by the present invention is to achieve both reduction of switching loss (high efficiency) by the partial switching operation and stable control of the DC voltage (stable control of the applied system).

  In order to solve the above problems, the present invention is characterized in that, in a power supply circuit using a constant boost ratio control method, the boost ratio is corrected or changed when the power supply voltage or the load greatly changes.

  Specifically, in a power supply circuit using a constant boost ratio control method, the DC voltage of the power supply circuit is detected, and when the detected DC voltage value exceeds a preset set value, the deviation is used to increase the voltage. The ratio is corrected.

  Further, the boost ratio to be set itself is changed according to the load state of the power supply circuit.

  According to the present invention, fluctuations in DC voltage can be suppressed (overvoltage, voltage drop) even if the power supply voltage and load state fluctuate, and both high efficiency and stable control of the applied system can be achieved.

  In addition, by producing a control board (hybrid IC or module) using the present invention, control of the power supply circuit is simplified, and application of the power supply circuit capable of suppressing high power factor or harmonic current is promoted.

It is the whole block diagram which showed the implementation method of a power supply circuit. Example 1 It is the control block diagram which showed the implementation method of a power supply circuit. Example 1 It is operation | movement explanatory drawing of the implementation method of a power supply circuit. Example 1 It is operation | movement explanatory drawing of the implementation method of a power supply circuit. Example 1 It is explanatory drawing which shows an example of the utilization form of the control circuit of a power supply circuit. Example 1 It is the control block diagram which showed the implementation method of a power supply circuit. (Example 2) It is operation | movement explanatory drawing of the implementation method of a power supply circuit. (Example 2) It is operation | movement explanatory drawing of the implementation method of a power supply circuit. (Example 2) It is the whole block diagram which showed the implementation method of the motor drive device. (Example 3) It is the control block diagram which showed the implementation method of the motor drive device. (Example 3) It is operation | movement explanatory drawing which showed the implementation method of a motor drive device. (Example 3) It is operation | movement explanatory drawing which showed the implementation method of a motor drive device. (Example 3) It is the operation | movement waveform diagram which showed the implementation method of the motor drive device. (Example 3) It is the operation | movement waveform diagram which showed the implementation method of the motor drive device. (Example 3) It is explanatory drawing which shows an example of the utilization form of the control circuit of a motor drive device. (Example 3) It is the external view which showed the implementation method of an inverter air conditioner. Example 4 It is operation | movement explanatory drawing of the implementation method of an inverter air conditioner. Example 4

  The present invention is a power supply circuit composed of a rectifier circuit and a smoothing circuit for converting an alternating current power source into a direct current, a switching element that performs switching operation based on a conduction ratio signal, a boost chopper circuit composed of an inductance and a diode, and an alternating current power source. Input current information generating means for generating inflowing input current information; generating a second coefficient from the input current information and the set first coefficient; obtaining a product of the second coefficient and the input current information; Load state generation that generates load state information indicating the state of a load connected to the smoothing circuit in a power supply circuit having a control means for creating a conduction ratio signal that defines the operation of the switching element based on at least this product And coefficient correction means for correcting the first coefficient using load state information.

  The load state generation means uses the DC voltage information of the smoothing circuit as load state information, and the power supply voltage state generation means uses the DC voltage information of the smoothing circuit as power supply voltage state information. .

  Furthermore, the module includes an inverter circuit that drives a motor as a load of the power circuit, and a control circuit that controls the power circuit and the inverter circuit on the same substrate, and the first coefficient is calculated based on the rotational speed of the motor, the load state, or It changes according to at least one information of an external signal.

  Next, a power supply circuit comprising a rectifier circuit and a smoothing circuit for converting AC power into DC, a switching element that performs switching operation based on a conduction ratio signal, a step-up chopper circuit comprising an inductance and a diode, and an inflow from the AC power supply Input current information generating means for generating input current information to be generated, a second coefficient is generated from the input current information and the set first coefficient, a product of the second coefficient and the input current information is obtained, and at least Power supply voltage state generation for generating power supply voltage state information indicating the state of the power supply connected to the rectifier circuit in a power supply circuit provided with a control means for creating a duty ratio signal that defines the operation of the switching element based on this product And coefficient correction means for correcting the first coefficient using the power supply voltage state information.

  Further, the power supply circuit includes a rectifier circuit that converts AC power into DC and a smoothing circuit, a switching element that performs a switching operation based on a conduction ratio signal, a step-up chopper circuit that includes an inductance and a diode, and an AC power source. An input current information generating means for generating input current information, a second coefficient is generated from the input current information and the set first coefficient, a product of the second coefficient and the input current information is obtained, and at least the product DC power generating means for generating DC voltage information indicating the state of the DC voltage of the smoothing circuit, and a DC voltage in a power supply circuit comprising a control means for creating a duty ratio signal that defines the operation of the switching element based on Coefficient correction means for correcting the first coefficient using information is provided.

  Further, the present invention is characterized by comprising coefficient correction means for correcting the first coefficient based on the deviation between the DC voltage information and the set reference value, and performing the correction using a proportional / integral compensator.

  Further, a first correction value for correcting the first coefficient is calculated using a proportional / integral compensator from the deviation between the DC voltage information and the set first reference value, and the DC voltage information and the set first reference value are calculated. A second correction value for correcting the first coefficient is calculated from the deviation from the reference value of 2 using a proportional / integral compensator, and the first coefficient is calculated using the first correction value and the second correction value. Coefficient correction means for correcting the above is provided.

  In the power supply circuit, a limiter is provided for a correction value for correcting the first coefficient.

  Further, a first correction value for correcting the first coefficient is calculated using a proportional / integral compensator from the deviation between the DC voltage information and the set first reference value, and the DC voltage information and the set first reference value are calculated. A second correction value for correcting the first coefficient is calculated from the deviation from the reference value of 2 using a proportional / integral compensator, and the first correction value and the second correction value are used to calculate the first correction value. Coefficient correction means for correcting the coefficient is provided.

  The first reference value is set to be equal to or lower than an overvoltage value as a power supply circuit or motor drive system, and the second reference value is set to be equal to or higher than a minimum voltage value of the power supply circuit or motor drive system. To do.

  The motor drive device is applied to drive the compressor driving motor of the air conditioner, and the first coefficient is changed according to the rotation speed or load state of the motor, and the first coefficient is set to the DC voltage and the reference value. It is characterized by using and correcting.

  A power supply circuit comprising a rectifier circuit for converting alternating current power to direct current and a smoothing circuit, comprising a switching element for switching operation based on a conduction ratio signal, a boost chopper circuit comprising an inductance and a diode, and connected to the smoothing circuit In a power supply device that supplies DC power to a load or its control circuit, input current information flowing from the AC power supply and DC voltage information of the smoothing circuit are input to output a duty ratio signal, and the input current waveform is synchronized with the power supply voltage. The continuity signal is controlled in the vicinity of the center of the half cycle of the power supply voltage, or the switching operation becomes a signal with the minimum pulse width, the period of which is the magnitude of the power supply voltage, Or, it changes according to at least one of the magnitudes of the load, or at the same time, the DC voltage exceeds a certain value or another Characterized in that it does not become a value below.

  In addition, the input current waveform is a waveform in which the switching operation does not enter near the peak of the current waveform, and the period during which the switching operation does not enter changes according to the magnitude of the power supply voltage or the magnitude of the load, Or, at the same time as the change, the direct current voltage is not more than a certain value or less than another certain value.

  Furthermore, when at least one of the magnitude of the power supply voltage or the load changes, there is an area where the DC voltage changes and an area where the DC voltage is controlled to a predetermined value. The switching operation is stopped near the center of the half cycle of the voltage, or the signal has the minimum pulse width. When the DC voltage is controlled to the specified value, the switching operation of the duty ratio signal is stopped, or the minimum pulse The width period changes.

  When at least one of the magnitude of the power supply voltage or the load changes, there are areas where the DC voltage changes and areas where the DC voltage is controlled to a predetermined value, and the current waveform is the peak of the current waveform. When the direct current voltage is controlled to a predetermined value, the current waveform is characterized in that the period during which the switching operation is not performed changes near the peak of the current waveform.

  Further, the power supply device or its control circuit is characterized in that the switching operation of the duty ratio signal when the input current is 16 A is stopped, or the period when the pulse width becomes the minimum is 90% or less of that when the input current is 2 A. To do.

  In the power supply device or its control circuit, the period during which the switching operation is not performed near the peak of the current waveform when the input current is 16 A is 90% or less of that when the input current is 2 A.

  A first embodiment of the present invention will be described with reference to FIGS. 1 is an overall configuration diagram of the power supply circuit of the present embodiment, FIG. 2 is a control block diagram showing the contents of control, FIGS. 3 and 4 are operation explanatory diagrams of the present embodiment, and FIG. 5 operates the power supply circuit shown in FIG. It is a general-view figure which shows an example of the utilization form of the control circuit to be made.

  The configuration and operation of the power supply circuit will be described with reference to FIG. The power circuit includes a rectifier circuit 2 connected to an AC power source 1, a step-up chopper circuit 3, a smoothing capacitor 4, and a control circuit 5, and supplies DC power to a load 6 connected to the output terminal of the smoothing capacitor 4. To do.

  The step-up chopper circuit 3 includes a reactor 32, a switching element 31 that short-circuits the AC power supply 1 via the reactor 32, and a diode 33 that supplies a terminal voltage of the switching element 31 to the smoothing capacitor 4. It is a circuit that boosts the DC voltage by using the switching operation of the switching element 31 and the energy storage effect by the reactor 32. Here, the switching element 31 uses a self-quenching element such as an IGBT or a transistor, and is driven according to a drive signal 51 a from the control circuit 5.

  The control circuit 5 detects the input current flowing from the AC power supply 1 using the shunt resistor 53 and the amplifier circuit 52 and outputs the input current value 5b, and the terminal voltage of the smoothing capacitor 4. A DC voltage detection circuit for detecting a DC voltage and outputting a DC voltage value 5c; an arithmetic means 50 for calculating a duty ratio signal 5a for controlling the switching element 31 according to the input current value 5b and the DC voltage value 5c; The drive circuit 51 is configured to amplify the duty ratio signal 5a and output a drive signal 51a for driving the switching element 31. The details of the DC voltage detection circuit are not shown here, but can be realized with a simple circuit configuration by using a voltage dividing circuit using a resistor.

  The computing means 50 uses a semiconductor computing element (hereinafter referred to as a microcomputer) typified by a single chip microcomputer, and the input current value 5b and the DC voltage value 5c are obtained by using an A / D converter built in the microcomputer. It is converted into a digital value for calculation. The duty ratio signal 5a is output in the form of a PWM pulse signal using a PWM timer built in the microcomputer.

  In this embodiment, digital calculation using a microcomputer will be described, but the same effect can be obtained by using calculation means using an analog calculation circuit such as a transistor, an operational amplifier or a comparator.

  Next, the contents of the calculation performed in the calculation means 50 will be described with reference to FIG. In this description, a part for calculating the conduction ratio signal 5a using the input current value 5b and the DC voltage value 5c will be described. The part that creates the PWM pulse signal from the calculated duty ratio signal 5a using the PWM timer is a function of the microcomputer, and is therefore omitted.

  The control block diagram of FIG. 2 includes a boost ratio constant control unit 50A that is a conventional technique and a boost ratio correction unit 50B that is the present invention.

  The step-up ratio constant control unit 50A uses the product of the input current instantaneous value (absolute value) | is | and the proportional gain Kp as the power supply voltage without detecting a reference sine wave current command or power supply phase. It consists of a basic method for controlling to a synchronized sine wave waveform and a constant step-up ratio control method for stopping the switching operation near the peak of the input current to reduce switching loss.

  Here, the basic method and the constant boost ratio control method will be briefly described.

  When the duty ratio signal (on-time ratio) d of the switching element 31 of the step-up chopper circuit 3 shown in FIG. 1 is given as in Expression (1), the input current is is as in Expression (2). (Details of derivation are omitted) As can be seen from equation (2), the input current is is a sine wave synchronized with the power supply voltage Vs even without a reference waveform such as a power supply voltage waveform. This is the principle of the basic method.

ここで、１：１００％通流率，Ｋｐ：電流制御ゲイン，ｉｓ：入力電流（瞬時値）

Here, 1: 100% conduction ratio, Kp: current control gain, is: input current (instantaneous value)

ここで、Ｖｓ：電源電圧実効値，Ｅｄ：直流電圧，ω：電気角周波数

Here, Vs: power supply voltage effective value, Ed: DC voltage, ω: electrical angular frequency

  In the basic method, the DC voltage Ed can be controlled by determining the proportional gain Kp from the DC voltage deviation.

  Here, if equation (2) is transformed,

となり、式（３）は、瞬時の昇圧比を示している。

Equation (3) shows the instantaneous step-up ratio.

  Here, when considering the step-up ratio a on an effective value basis,

ここで、Ｉｓ：入力電流（実効値）
となり、Ｋｐ・Ｉｓを一定に制御すれば、直流電圧Ｅｄは電源電圧Ｖｓのａ倍に制御できる。

Where Is: input current (effective value)
Thus, if Kp · Is is controlled to be constant, the DC voltage Ed can be controlled to a times the power supply voltage Vs.

  Based on the above method, if the duty ratio signal d is given by

  The duty ratio signal d becomes 0% when the input current | is | exceeds a · Is, and the switching operation is stopped. As a result, the input current has a waveform in which the chopper does not enter near the peak of the power supply voltage (region where the input current exceeds a · Is), and switching loss can be reduced. This is the principle of constant boost ratio control.

  By controlling as described above, the input current waveform can be controlled in a sine wave shape synchronized with the power supply voltage using only the instantaneous value of the input current and proportional gain without detecting the reference sine wave current command waveform or power supply phase. The switching operation near the peak value of the input current can be stopped (partial switching operation).

  A block diagram of the above equation gives 50A in FIG. Here, the input current effective value Is is calculated by using the filter means 500 to calculate the input current value 5b. However, an average value or an effective value may be calculated and controlled. The step-up ratio a uses a preset value.

  Further, in this block diagram, in the calculation of the conduction ratio signal d, as shown in Expression (1) and Expression (5), the instantaneous value of input current (absolute value) | is | from the maximum conduction ratio of 1 (100%) In the actual PWM timer setting, the product of the input current instantaneous value (absolute value) | is | and the proportional gain Kp is considered as the off-time ratio. In this case, it is not necessary to subtract from 1 which is the maximum flow rate.

  The step-up ratio correction unit 50B calculates a correction value for the step-up ratio a by using a proportional / integral compensator 501 from the deviation between the preset limit value EdLim1 and the detected DC voltage value 5c, and corrects the step-up ratio a. It is the composition which performs.

  Here, the present embodiment is intended to prevent the DC voltage from exceeding the overvoltage protection value due to fluctuations in the power supply voltage or load, so that the operation stops. Therefore, the limit value EdLim1 is greater than the overvoltage protection value of the power supply circuit. It is set to a low value. Further, the limiter 503 is set so that the correction operation of the boost ratio a is performed only when the DC voltage value exceeds the limit value EdLim1 (operates only in the direction of decreasing the boost ratio).

  As described above, this embodiment is realized by combining the conventional boost ratio constant control unit 50A and the boost ratio correction unit 50B of the present invention.

  The operation and effect of this embodiment will be described with reference to the operation explanatory diagrams of FIGS. In the present specification, for the sake of simplification of explanation and drawing, each value change is represented by an ideal response. Actually, there is an influence such as control delay, and the characteristic does not become as shown in this figure. The characteristics differ depending on the control gain setting of the proportional / integral compensator.

  FIG. 3 is a diagram showing an operation in the case where the horizontal axis represents time, the vertical axis represents the step-up ratio a, the DC voltage Ed, and the power supply voltage Vs, and the power supply voltage Vs greatly fluctuates at times t1 and t2.

  Here, the step-up ratio a and the DC voltage Ed are shown together with the operation in the conventional technique (only the step-up ratio constant control unit 50A) (displayed with a dotted line) and the present invention (displayed with a solid line).

  When the power supply voltage Vs rises rapidly at t1, the DC voltage Ed exceeds the overvoltage set value EdMAX because the boost ratio a is fixed in the conventional technology, the overvoltage protection is activated, and the switching operation is stopped (the DC voltage drops rapidly). To do).

  On the other hand, in the present invention, when the DC voltage exceeds the limit value EdLim1, the boost ratio a is corrected, and the DC voltage is maintained at the limit value EdLim1. As a result, the overvoltage protection can be prevented from operating, and the system operation can be maintained. If the power supply voltage Vs returns to a normal value at t2, the correction of the boost ratio a also returns to the normal value (set value), and the normal DC voltage is maintained.

  FIG. 4 is a diagram illustrating an operation when the horizontal axis represents time, the vertical axis represents the step-up ratio a, the DC voltage Ed, and the load L, and the load L changes greatly at times t1 and t2.

  Here, the step-up ratio a and the direct-current voltage Ed are shown together in the case of the prior art (displayed by a dotted line) and the operation of the present invention (displayed by a solid line), as in FIG.

  When the load L suddenly drops at t1, the DC voltage Ed exceeds the overvoltage set value EdMAX because the boost ratio a is fixed in the conventional technique, the overvoltage protection is activated, and the switching operation is stopped (the DC voltage suddenly drops). To do).

  On the other hand, in the present invention, as in FIG. 3, when the DC voltage exceeds the limit value EdLim1, the boost ratio a is corrected, and the DC voltage is maintained at the limit value EdLim1. As a result, the overvoltage protection can be prevented from operating, and the system operation can be maintained. If the load L returns to the original value at t2, the correction of the step-up ratio a also returns to the set value, and the normal DC voltage is maintained.

  As described above, even if the power supply voltage or the load fluctuates greatly, the increase of the DC voltage can be suppressed to the limit value or less, and the overvoltage protection stop of the system can be prevented. Further, in a normal state, the operation is performed at a preset step-up ratio a, so that the operation with the optimum efficiency, power factor and harmonic current is possible.

  Here, it goes without saying that the above characteristic (response) changes depending on the gain set in the proportional / integral compensator. In an actual system, it is necessary to set the limit value EdLim1 and the set gain in accordance with the characteristics required by the system.

  Next, an example of a usage form of a control circuit for operating the power supply circuit of this embodiment will be described with reference to FIG.

  This usage form is an overview of the control circuit 5 shown in FIG. However, it is desirable that the shunt resistor 53 is not installed in the hybrid IC for the purpose of component change or noise countermeasure, but in the same space as the power circuit components such as the switching element 31.

  The input / output terminals of the control circuit 5 shown in FIG. 1 are an input current detection terminal, a DC voltage detection terminal, and a drive signal output terminal, but in addition to this, a boost ratio setting terminal and a DC voltage limit value setting By installing a terminal, a load state information detection terminal for detecting the state of the connected load, a function, and the like, a hybrid IC with increased versatility can be realized.

  A second embodiment of the present invention will be described with reference to FIGS. The same reference numerals as those in the first embodiment perform the same operations, and a description thereof will be omitted. FIG. 6 is a control block diagram of the present embodiment, and FIGS. 7 and 8 are operation explanatory diagrams of the present embodiment. The overall circuit configuration is the same as in FIG.

  As in the first embodiment, FIG. 6 includes a boost ratio constant control unit 50A that is a conventional technique and a boost ratio correction unit 50C that is the present invention. The step-up ratio correction unit 50C has the same configuration as the step-up ratio correction unit 50B described in the first embodiment, and only the limit value EdLim2 and the limiter 504 are different. The proportional / integral compensator 502 performs the same operation as the proportional / integral compensator 501 shown in FIG.

  In the first embodiment, the operation is to suppress the overvoltage of the DC voltage, but this embodiment is configured to prevent the DC voltage from decreasing. Therefore, the limiter 504 is set to correct the boost ratio a only when the DC voltage value falls below the limit value EdLim2 (operates only in the direction of increasing the boost ratio).

  In the operation explanatory diagram of FIG. 7, the horizontal axis represents time, the vertical axis represents the step-up ratio a, the DC voltage Ed, and the power supply voltage Vs, and the power supply voltage Vs fluctuated greatly at times t1 and t2. It is the figure which showed the operation | movement in the case. Here, the step-up ratio a and the DC voltage Ed are shown together with the operation in the case of the prior art (displayed by a dotted line) and the present invention (displayed by a solid line).

  When the power supply voltage rapidly decreases at t1, the DC voltage Ed also decreases rapidly in the same manner as the power supply voltage because the boost ratio a is fixed in the prior art. Here, when the low voltage protection set value EdMIN is set as the power supply circuit system, the low voltage protection is activated and the power supply circuit system is stopped, and the system operation cannot be maintained.

  On the other hand, in the present invention, when the DC voltage becomes equal to or lower than the limit value EdLim2, the boost ratio a is corrected, and the DC voltage is maintained at the limit value EdLim2. As a result, the low voltage protection can be prevented from operating, and the system operation can be maintained. If the power supply voltage Vs returns to a normal value at t2, the correction of the boost ratio a also returns to the normal value (set value), and the normal DC voltage is maintained.

  FIG. 8 is a diagram showing an operation when the horizontal axis represents time, the vertical axis represents the step-up ratio a, the DC voltage Ed, and the load L, and the load L changes greatly at times t1 and t2.

  When the load L suddenly rises at t1, the DC voltage Ed becomes lower than the low voltage protection set value EdMIN because the step-up ratio a is fixed in the conventional technique, the low voltage protection is activated, and the switching operation is stopped (the DC voltage is further steepened). descend).

  On the other hand, in the present invention, as in FIG. 7, when the DC voltage becomes equal to or less than the limit value EdLim2, the boost ratio a is corrected, and the DC voltage is maintained at the limit value EdLim2. As a result, the low voltage protection can be prevented from operating, and the operation of the system can be maintained. If the load L returns to the original value at t2, the correction of the step-up ratio a also returns to the set value, and the normal DC voltage is maintained.

  As described above, even if the power supply voltage or the load fluctuates greatly, it is possible to suppress the decrease in the DC voltage to the limit value and to prevent the system from stopping the low voltage protection. Further, in a normal state, the operation is performed at a preset step-up ratio a, so that the operation with the optimum efficiency, power factor and harmonic current is possible.

  Here, in the first and second embodiments, the operation has been described by taking an example of a transient fluctuation. However, the fluctuation of the power source and the load is not necessarily limited to the transient case, but to the slow fluctuation. However, the same configuration can be used.

  A third embodiment of the present invention will be described with reference to FIGS. The same reference numerals as those in the first and second embodiments perform the same operation, and the description thereof will be omitted.

  FIG. 9 is an overall configuration diagram of the motor drive device of the present embodiment, FIG. 10 is a control block diagram showing the control contents, FIGS. 11 and 12 are operation explanatory diagrams of the present embodiment, and FIGS. 13 and 14 flow into the power supply circuit. FIG. 15 is an external view of a module showing an example of a usage pattern of this embodiment.

  FIG. 9 shows a configuration in which a motor drive circuit comprising a motor 9 and an inverter circuit 8 is connected as a load of the power circuit of the present invention, and the control circuit of the power circuit of the present invention and the control circuit of the inverter circuit 8 are integrated. It has become. In other words, the control circuit 7 shown in FIG. 9 is configured to use a microcomputer and to control the power supply circuit and the inverter circuit with one microcomputer.

  Only the parts different from the first and second embodiments will be described. The inverter circuit 8 is an inverter circuit composed of an IGBT and a diode, and the motor 9 is a permanent magnet synchronous motor.

  Further, although the configuration of the step-up chopper circuit is different from those of the first and second embodiments, this circuit configuration can operate in the same manner as the first and second embodiments. Here, the diodes 21 and 22 in the rectifier circuit 2 perform the same operation as the diode 33 of the boost chopper circuit 3 of the first and second embodiments, in addition to the rectification operation of the power supply. In other words, the diodes 21 and 22 perform the above-described two operations, and this circuit configuration has an effect of reducing the loss of one diode.

  As described above, the control circuit 7 uses the microcomputer to control the power supply circuit and the inverter circuit of the present invention, and the microcomputer (calculating means 70) controls the power supply circuit described in the first and second embodiments. And control calculation of the inverter circuit.

  The configuration of the control circuit of the power supply circuit section shown in FIG. 10 is a configuration that combines the contents described in the first and second embodiments (50B and 50C are combined into 50D), and thus description thereof is omitted. . Here, the configuration of the control circuit of the inverter circuit unit will be briefly described.

  In the motor control of the present embodiment, since motor current sensorless and position sensorless vector control is performed, only the DC current flowing through the shunt resistor 73 installed on the DC side is detected from the inverter circuit. Specifically, as shown in FIG. 9, the voltage generated in the shunt resistor 73 is amplified by the amplifier circuit 72 and is taken in as a DC current detection value 7b by using an A / D converter of a microcomputer. Further, the PWM signal 7a given to the switching element of the inverter circuit is given to the inverter circuit via the drive circuit 71 as the drive signal 71a.

  Here, although not shown in the figure, the calculation means 70 incorporates the power supply circuit control means and motor current sensorless / position sensorless vector control means described in the first and second embodiments. Information exchange of values is possible. With the above configuration, the power supply circuit performs the same operation as in the first and second embodiments.

  Next, the operation of this embodiment will be described with reference to FIGS. Although the first and second embodiments have been described with dynamic (transient) operations, this embodiment will be described with static operations.

  FIG. 11 shows the step-up ratio a and the DC voltage Ed for the load. In this embodiment, as shown in FIG. 10, the control configuration described in the first and second embodiments is combined, and the DC voltage changes between the limit value EdLim1 and the limit value EdLim2. It becomes operation.

  For example, when the load becomes a light load equal to or less than the load L1, the boost ratio correction unit 50B operates, the boost ratio a is corrected (decreased), and the DC voltage is controlled to the limit value EdLim1. On the contrary, when the load becomes a high load equal to or higher than the load L2, the boost ratio correction unit 50C operates, the boost ratio a is corrected (increased), and the DC voltage is controlled to the limit value EdLim2.

  FIG. 12 shows the step-up ratio a and the direct-current voltage Ed with respect to the power supply voltage. The movement of the step-up ratio a and the direct-current voltage Ed is the same as in FIG.

  Here, FIG. 13 and FIG. 14 show the experimental results of the input current (reactor current) flowing into the power supply circuit and the waveform of the power supply voltage when the load is changed with the power supply voltage kept constant.

  FIG. 13 shows the experimental results when the conventional technique (only the step-up ratio constant control unit 50A is used) and FIG. 14 shows the experimental results when the present invention is used. 13 and 14, (a) shows the result when the input current is 2A, and (b) shows the result when the input current is 16A. In addition, a switching OFF period in the partial switching operation is also shown.

  From this figure, the conventional technique does not adjust (change) the step-up ratio a even when the load changes, so the switching OFF period is also approximately the same time interval, and the distortion rate of the input current waveform also increases as the load increases. It has a large waveform. Although not shown here, the harmonic current also increases in the current waveform of FIG.

  On the other hand, as shown in FIG. 14, the input current waveform using the present invention changes in the switching OFF period (decreases by about 15%) and is a waveform with a small distortion rate. Although the harmonic current value is not shown, the waveform of FIG. 14B also decreases the harmonic current value.

  FIG. 15 is a schematic view of a module in which a power supply circuit, an inverter circuit, and a control circuit are integrated as an example of a usage form of the present embodiment.

  This module is an integrated module in which a power semiconductor such as an IGBT or a diode is mounted on the bottom in a bare chip and a control circuit is disposed on the upper substrate. By modularization, the application of the present invention becomes easy, and a low-cost system can be constructed.

  Here, although the present embodiment has been described with an inverter circuit using vector control, the same effect can be obtained by using a 120-degree control type inverter circuit that has been widely used in the past.

  Further, in this embodiment, the power supply voltage and the load state (change) are detected by detecting the DC voltage. As the load state information, for example, the motor rotation speed, the input current, the DC current, the DC voltage, Any value that varies depending on the load condition such as DC power, DC voltage pulsation width, input power, torque, peak value ratio of inverter circuit, and inverter conduction ratio may be used. Two or more of the above values may be used in combination.

  As described above, when the present invention is applied, it is possible to construct a system that can continue operation even when the power supply voltage or the load fluctuates and can be operated with optimum efficiency in normal times. In addition, if the setting of the boost ratio and the limit value is optimized, the harmonic current can be automatically suppressed simultaneously with the high efficiency operation.

  A fourth embodiment of the present invention will be described with reference to FIGS. The same reference numerals as those in the above-described embodiments (1 to 3) perform the same operation, and the description thereof will be omitted.

  FIG. 16 is an external view of an inverter air conditioner when the motor driving apparatus described in the third embodiment is applied to a compressor driving motor driving apparatus for an inverter air conditioner, and FIG. It is operation | movement explanatory drawing at the time of changing according to).

  In the above-described embodiment, the content of correcting the boost ratio a when the DC voltage is equal to or higher than the limit value has been described. However, in order to achieve both higher efficiency and higher output, the boost ratio a The set value itself needs to be changed according to the load of the system (inverter air conditioner).

  FIG. 16 shows an external view of a separate type inverter air conditioner as an example, and is composed of an outdoor unit 600 and an indoor unit 400. In the outdoor unit 600, a compressor 300 and an outdoor fan 100 integrated with a motor, and a motor driving device 200 that drives the compressor 300 and the outdoor fan 100 are installed.

  In this embodiment, a method for changing the step-up ratio a according to the state of the rotation speed of the compressor driving motor of the inverter air conditioner will be described with reference to FIG.

  Basically, the step-up ratio a may be fixed as in the above-described embodiment, but the step-up ratio a is changed in a load state in consideration of further efficiency improvement, stabilization of motor control and higher output.

  In FIG. 17, the horizontal axis represents the motor rotation speed, and the vertical axis represents the step-up ratio a and the DC voltage Ed. As shown in FIG. 17, in a region where the rotational speed of the motor is low, in other words, in a state where the load is light, the operation is performed with the step-up ratio a lowered. In this case, since the DC voltage can be kept low, the switching loss of the power supply circuit and the like can be reduced, and the loss of the inverter circuit and the motor can be reduced, so that highly efficient operation is possible.

  However, in this case, the harmonic component of the input current waveform increases and the power source power factor also decreases. Therefore, the boost ratio a needs to be set in consideration of the above.

  If the number of rotations (load) of the motor further increases, the harmonic component of the input current may not enter the standard value, or the power factor may be greatly reduced. Further, the DC voltage Ed also decreases. Therefore, if the step-up ratio a is increased as the motor rotation speed (load) increases, high-efficiency operation can always be performed according to the motor rotation speed (load).

  In this embodiment, the step-up ratio a is changed stepwise according to the motor rotation speed, but it is necessary to provide hysteresis in actual operation (not shown). The step-up ratio a may be changed linearly or using a certain function. Further, it is possible to control the rotational speed using the step-up ratio a. In other words, it is possible to control the rotation speed of the motor by changing the step-up ratio a and changing the DC voltage.

  Here, as load state information, for example, motor rotation speed, input current, DC current, DC voltage, DC power, DC voltage pulsation width, input power, torque, peak value ratio of inverter circuit, inverter conduction ratio, etc. Any value that changes depending on the load condition is acceptable. Two or more of the above values may be used in combination.

  As described above, by changing the step-up ratio a that is set according to the load of the inverter air conditioner, it is possible to achieve both higher efficiency and higher output, even if there are (unexpected) power supply fluctuations and load fluctuations. System stop can be prevented.

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Rectifier circuit 3 Boost chopper circuit 4 Smoothing capacitor 5, 7 Control circuit 6 Load 8 Inverter circuit 9 Motor 50, 70 Calculation means 50A Boost ratio constant control part 50B, 50C, 50D Boost ratio correction part

Claims (5)

A power supply circuit comprising a rectifier circuit for converting an alternating current power source into a direct current and a smoothing circuit, comprising a switching element that performs a switching operation based on a conduction ratio signal, a boost chopper circuit comprising an inductance and a diode, and is connected to the smoothing circuit. In a power supply device or a control circuit for supplying DC power to a load,
Control means for controlling the input current waveform to a sine wave in synchronization with the power supply voltage by inputting the input current information flowing from the AC power supply and the DC voltage information of the smoothing circuit as inputs. ,
The duty ratio signal stops the switching operation near the center of the half cycle of the power supply voltage, or becomes a signal with a minimum pulse width,
An overvoltage protection level and a low voltage protection setting value for stopping the operation of the power supply circuit, a first limiting value is the overvoltage protection level values less than said a value greater than the low voltage protection setting value A second limit value that is smaller than the first limit value, and
When the DC voltage is less than or equal to the first limit value and greater than or equal to the second limit value, a period during which the switching operation is stopped near the center of the half cycle of the power supply voltage, or a minimum pulse width and The period to be a preset value,
When the DC voltage is larger than the first limit value, a period during which the switching operation is stopped near the center of the half cycle of the power supply voltage so that the DC voltage becomes the first limit value, or a minimum pulse Widen the period to be wider than the preset value ,
When the DC voltage is smaller than the second limit value, the switching operation is stopped near the center of the half cycle of the power supply voltage so that the DC voltage becomes the second limit value, or the minimum pulse A power supply apparatus or a control circuit for the power supply apparatus, wherein a period of width is narrower than the preset value . A power supply circuit comprising a rectifier circuit for converting an alternating current power source into a direct current and a smoothing circuit, comprising a switching element that performs a switching operation based on a conduction ratio signal, a boost chopper circuit comprising an inductance and a diode, and is connected to the smoothing circuit. In a power supply device or a control circuit for supplying DC power to a load,
Control means for controlling the input current waveform to a sine wave in synchronization with the power supply voltage by inputting the input current information flowing from the AC power supply and the DC voltage information of the smoothing circuit as inputs. ,
The input current waveform is a waveform in which switching operation does not enter near the peak of the current waveform,
An overvoltage protection level and a low voltage protection setting value for stopping the operation of the power supply circuit, a first limiting value is the overvoltage protection level values less than said a value greater than the low voltage protection setting value A second limit value that is smaller than the first limit value, and
When the DC voltage is equal to or less than the first limit value and equal to or greater than the second limit value, a period in which the switching operation does not enter near the peak of the current waveform is set as a preset value,
When the DC voltage is greater than the first limit value, the preset value is a period during which no switching operation is performed near the peak of the current waveform so that the DC voltage becomes the first limit value. Wider than
When the DC voltage is smaller than the second limit value, the preset value is a period during which the switching operation does not occur near the peak of the current waveform so that the DC voltage becomes the second limit value. power supply or a control circuit, characterized in that the narrowed than. When the DC voltage is greater than the first limit value , a period during which no switching operation is performed near the peak of the current waveform is set based on a deviation between the DC voltage and the first limit value. Wider than the existing value,
When the DC voltage is smaller than the second limit value , a period during which no switching operation is performed near the peak of the current waveform is set based on a deviation between the DC voltage and the second limit value. The power supply device or the control circuit thereof according to claim 1, wherein the power supply device is narrower than a certain value .   2. The power supply device according to claim 1, wherein a period during which the switching operation is stopped in the vicinity of the center of the half cycle of the power supply voltage or a period when the minimum pulse width is obtained is changed according to the motor rotation speed or the load. Its control circuit.   The power supply device or a control circuit thereof according to claim 2, wherein a period during which no switching operation is performed near a peak of the current waveform is changed according to a motor rotation speed or a load.

Images