JP2013106455A - Dc power-supply device and air conditioner using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve efficiency improvement, power-factor improvement, and resolution of high-frequency problems at a high level.SOLUTION: A DC power-supply device 11A includes: first and second rectifier circuits 17a and 17b converting AC power from an AC power supply 13 into DC power; a reactor 15 connected to the first and second rectifier circuits 17a and 17b; a switching section 19 short-circuiting the AC power supply 13 via the reactor 15; an input-current acquisition section 27 acquiring a current from the AC power supply 13; an input-voltage acquisition section 25 acquiring a voltage across the AC power supply 13; a DC-output-voltage acquisition section 31 acquiring a DC output voltage across the first and second rectifier circuits 17a and 17b; and a switching control section 43 determining a short-circuit time width of the switching section 19 on the basis of a short-circuit timing of the switching section 19, the DC output voltage, the voltage across the AC power supply 13, and information of the current from the AC power supply.

Description

  The present invention relates to a DC power supply device that converts AC power from an AC power supply into DC power, and an air conditioner using the DC power supply device.

  For example, home air conditioners have been strongly required to save resources and energy in response to demands for global environmental protection. In addition, with the rapid increase in electronic control devices, there is a need for products that comply with harmonic current regulations that adversely affect the quality of power supplies.

  In order to satisfy these requirements, a power supply device according to Patent Document 1 is known. The power supply device according to Patent Document 1 includes a reactor having one end connected to an AC power supply, and a bidirectionally conductive short-circuit element that short-circuits / opens the AC power supply via the reactor, according to the load amount. Power supply mode without short circuit operation, partial switching mode in which short circuit operation is performed once or a plurality of times in a half cycle of the power supply voltage, or high frequency switching in which short circuit operation is performed at high frequency by current feedback control. Control by any of the modes.

  According to the power supply device according to Patent Document 1, in the partial switching mode, the energy accumulated in the reactor can be controlled by controlling the short circuit start time (timing) of the short circuit element, the short circuit time width, and the number of short circuits. As a result (see the description in paragraph 0037 of Patent Document 1), it is possible to realize improvement in efficiency, improvement in power factor, and elimination of high-frequency problems.

JP 2003-153543 A

  However, in the power supply device according to Patent Document 1, in order to realize efficiency improvement, power factor improvement, and elimination of high-frequency problems at a high level, specifics on how to control the short-circuit time width of the short-circuit element. There is no specific description. Therefore, the power supply device according to Patent Document 1 has room for improvement in that there is no specific description for realizing efficiency improvement, power factor improvement, and elimination of high-frequency problems at a high level.

  It is an object of the present invention to improve the efficiency, improve the power factor, and solve the high frequency problem at a high level.

  A DC power supply device according to the present invention includes a rectifier circuit that converts AC power from an AC power supply into DC power, a reactor connected to the rectifier circuit, a switching unit that short-circuits the AC power supply via the reactor, An input current acquisition unit that acquires a current from the AC power source, an input voltage acquisition unit that acquires a voltage of the AC power source, a zero cross detection unit that detects a zero cross point of the AC power source, and a frequency of the AC power source Synchronized with the zero-crossing point detected by the zero-crossing point detected by the zero-crossing detection unit, a frequency output unit for acquiring the DC output voltage of the rectifier circuit, a short-circuiting timing storage unit for storing the short-circuiting timing of the switching unit A switching control unit that performs control to short-circuit or open the switching unit, and the switching control unit The short-circuit timing stored in the short-circuit timing storage unit, the DC output voltage acquired by the DC output voltage acquisition unit, the voltage of the AC power source acquired by the input voltage acquisition unit, and acquired by the input current acquisition unit The main feature is that the short-circuit time width of the switching unit is determined based on the current information from the AC power supply.

  According to the present invention, efficiency improvement, power factor improvement, and elimination of high-frequency problems can be realized at a high level.

1 is a block diagram illustrating a circuit configuration of a DC power supply device according to a first embodiment of the present invention. It is a figure showing the pulse duty D and the input current theoretical waveform in the power supply frequency of 50 Hz. It is a figure showing the input current waveform by simulation in power supply frequency 50Hz. It is a figure showing the pulse duty D and the input current theoretical waveform in the power supply frequency of 60 Hz. It is a figure showing the input current waveform by simulation in power supply frequency 60Hz. It is a block diagram showing the circuit structure of the DC power supply device which concerns on 2nd Embodiment of this invention. It is a block diagram showing the circuit structure of the direct-current power supply device which concerns on 3rd Embodiment of this invention. It is a schematic block diagram of the air conditioner carrying the DC power supply device which concerns on either of the 1st-3rd embodiment of this invention. It is a perspective view showing the internal structure of the outdoor unit of the air conditioner. It is a top view showing the state which removed the top plate of the outdoor unit.

Hereinafter, a plurality of embodiments of the present invention will be described in detail with reference to the drawings.
[First Embodiment]
(Overall configuration of DC power supply device 11A according to the first embodiment)
First, the overall configuration of the DC power supply device 11A according to the first embodiment will be described with reference to FIG. FIG. 1 is a block diagram showing a circuit configuration of a DC power supply device 11A according to the first embodiment of the present invention. The DC power supply 11A according to the first embodiment of the present invention will be described by exemplifying a three-phase inverter circuit 21 that drives the motor 23 as a “load” of the present invention.

  As shown in FIG. 1, a DC power supply 11A according to the first embodiment of the present invention includes an AC power supply 13, a reactor 15, and first and second full-wave rectifications corresponding to the “rectifier circuit” of the present invention. Circuits 17a and 17b, a switching unit 19, a smoothing capacitor C1, an input voltage acquisition unit 25, an input current acquisition unit 27, a zero cross detection unit 29, a DC output voltage acquisition unit 31, and a control circuit 33. It is prepared for.

  The AC power supply 13 is, for example, a single-phase AC power supply. However, a three-phase AC power source may be adopted as the AC power source 13. A reactor 15 is connected to one side wiring L <b> 1 of the AC power supply 13. The reactor 15 plays a role of improving the power factor of the AC power supply 13.

  As shown in FIG. 1, the first full-wave rectifier circuit 17a includes first to fourth rectifier diodes D1 to D4 that are bridge-connected to each other. The first full-wave rectifier circuit 17a has a function of full-wave rectifying the AC voltage waveform of the AC power supply 13 using the first to fourth rectifier diodes D1 to D4.

  As shown in FIG. 1, the first to fourth rectifier diodes D <b> 1 to D <b> 4 are connected to the positive DC bus PL on the anode side and to the negative DC bus NL on the cathode side, respectively. Between the first connection point Nd1 located between the first and second rectifier diodes D1 and D2 and the second connection point Nd2 located between the third and fourth rectifier diodes D3 and D4. The AC power supply 13 is connected via the reactor 15 and the current sensor 27a.

  The second full-wave rectifier circuit 17b has a configuration similar to that of the first full-wave rectifier circuit 17a. That is, as shown in FIG. 1, the second full-wave rectifier circuit 17b includes fifth to eighth rectifier diodes D5 to D8 that are bridge-connected to each other. The second full-wave rectifier circuit 17b has a function of full-wave rectifying the AC voltage waveform of the AC power supply 13 using the fifth to eighth rectifier diodes D5 to D8.

  Between the third connection point Nd3 located between the fifth and sixth rectifier diodes D5 and D6 and the fourth connection point Nd4 located between the seventh and eighth rectifier diodes D7 and D8. The AC power supply 13 is connected via the reactor 15 and the current sensor 27a.

  The switching unit 19 made of a semiconductor switching element is connected between the anode side and the cathode side in the fifth to eighth rectifier diodes D5 to D8. As the semiconductor switching element, for example, an IGBT (Insulate Gate Bipola Transisitor) structure or a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) structure may be used as appropriate. The switching unit 19 has a function of short-circuiting the AC power supply 13 via the reactor 15.

The switching unit 19 is configured such that the timing, duration, and number of times related to the short circuit are controlled in accordance with the drive control signal of the switching control unit 43 included in the control circuit 33 described later.

  The smoothing capacitor C1 has a function of smoothing the direct-current voltage that has been full-wave rectified by the first full-wave rectifier circuit 17a. As shown in FIG. 1, the smoothing capacitor C1 having a pair of terminals has one terminal connected to the positive DC bus PL and the other terminal connected to the negative DC bus NL. DC power for driving the electric motor 23 is generated between both terminals of the smoothing capacitor C1 via the three-phase inverter circuit 21.

  The three-phase inverter circuit 21 serving as a load for the DC power supply device 11A according to the first embodiment converts the DC power rectified by the first full-wave rectifier circuit 17a and smoothed by the smoothing capacitor C1 into u-phase, v-phase, It has a function of converting to w-phase pseudo three-phase AC power and supplying the converted pseudo three-phase AC power to the motor 23.

  The input voltage acquisition unit 25 has a function of acquiring a voltage between terminals of the AC power supply 13. The input current acquisition unit 27 has a function of acquiring the magnitude of the current supplied from the AC power supply 13. The zero cross detection unit 29 has a function of acquiring a zero cross point (time information of a point where the AC voltage waveform passes on the time axis of zero potential) in the AC voltage waveform of the AC power supply 13. The DC output voltage acquisition unit 31 has a function of acquiring a DC voltage that is an output of the first full-wave rectifier circuit 17a. The acquired values in the acquisition units 25, 27, and 31 and the detection value of the zero cross detection unit 29 are configured to be sent to the control circuit 33.

  The control circuit 33 controls the timing, duration, and number of times that the switching unit 19 is short-circuited based on the acquired values in the respective acquisition units 25, 27, and 31 and the detection value of the zero cross detection unit 29. It has a function. In order to realize such a function, the control circuit 33 includes a converter control unit 35, an inductance storage unit 37, a short circuit timing storage unit 39, a frequency calculation unit 41, a switching control unit 43, an inverter control unit 45, And a PWM output unit 47.

  Converter control unit 35 plays a central role in the function of converting AC power from AC power supply 13 to DC power.

The inductance storage unit 37 has a function of storing the inductance value of the reactor 15. The inductance value of the reactor 15 stored in the inductance storage unit 37 is referred to when determining the duration of the short circuit of the switching unit 19.
Note that the storage content of the inductance storage unit 37 is configured to be able to be updated in accordance with the change when the inductance value of the reactor 15 changes, for example.

The short circuit timing storage unit 39 has a function of storing the short circuit timing (short circuit start time) of the switching unit 19. The short-circuit timing of the switching unit 19 stored in the short-circuit timing storage unit 39 is shifted so that the harmonic components of the short-circuit timings included therein do not overlap each other within a period of a power supply voltage half cycle described later. Is preferred. This is because the harmonic current can be suppressed.
Note that the storage content of the short-circuit timing storage unit 39 is configured to be able to be updated according to the request when the timing related to the short-circuit of the switching unit 19 needs to be adjusted, for example.

  The frequency calculation unit 41 has a function of calculating the frequency of the AC power supply 13 based on the zero cross acquisition value of the zero cross detection unit 29. Specifically, the frequency calculating unit 41 obtains the interval of the zero cross signal, and if the obtained interval is longer than 9 ms, for example, 50 Hz, and if it is shorter than 9 ms, the frequency of the AC power supply 13 is obtained. calculate.

  The switching control unit 43 includes information on the inductance value of the reactor 15 stored in the inductance storage unit 37, information on the short circuit timing stored in the short circuit timing storage unit 39, and the input acquired by the input voltage acquisition unit 25. Based on the voltage, the input current acquired by the input current acquisition unit 27, and the output voltage information acquired by the DC output voltage acquisition unit 31, the duration of the short circuit of the switching unit 19 is calculated, and this calculation According to the result, it has a function of controlling the open or short circuit operation of the switching unit 19.

  The inverter control unit 45 has a function of converting the DC power rectified by the first full-wave rectifier circuit 17a and smoothed by the smoothing capacitor C1 into pseudo three-phase AC power of u phase, v phase, and w phase. Play a central role.

  The PWM output unit 47 has a function of outputting a PWM (Pulse Width Modulation) signal for controlling the driving of the electric motor 23 and supplying the PWM signal thus output to the three-phase inverter circuit 21 via the inverter driver 49. .

  The control circuit 33 includes a microcomputer (hereinafter referred to as “microcomputer”) including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The microcomputer functions to read and execute a program stored in the ROM and to control execution of various functional units such as the switching control unit 43 included in the control circuit 33.

(Operation of DC Power Supply Device 11A According to First Embodiment)
Next, the operation of the DC power supply device 11A according to the first embodiment will be described.

  Prior to the description of the operation of the DC power supply device 11A according to the first embodiment, a harmonic margin as an index of the harmonic current will be described. The limit value of the n-th harmonic current of the power supply frequency is defined in JIS C61000-3-2, “Electromagnetic compatibility—Part 3-2: Limit value—Harmonic current generation limit value”. When the harmonic current is In with respect to this limit value Isn, the n-order margin is defined as (1-In / Isn).

  As is apparent from this definition, when the n-th order margin is smaller than 0, an n-th order harmonic current greater than or equal to the limit value Isn flows, which is not conforming to the specification. On the other hand, when the n-th order margin is larger than 0, n-th order harmonic current below the limit value is flowing, and the regulation conforms. When the nth order margin is close to 1, the nth order harmonic current approaches 0. This is a very good state with almost no n-order harmonic current that adversely affects the power supply. The above-mentioned n-th order margin is obtained from the second order to the 40th order, and the smallest one is defined as a margin of harmonics.

  As shown in FIG. 1, the DC power supply device 11A rectifies the AC voltage of the AC power supply 13 by the first full-wave rectifier circuit 17a, smoothes it by the smoothing capacitor C1, converts it to a DC voltage, and converts the converted DC voltage. Is supplied to the three-phase inverter circuit 21 and the electric motor 23 as loads.

  The source of DC voltage in the DC power supply device 11A is the electric charge stored in the smoothing capacitor C1. For this reason, when the AC voltage of the AC power supply 13 exceeds the DC voltage appearing at both ends of the smoothing capacitor C1, a current flows to the load. As a result, the energization section is short, the current waveform is sharp, and the power factor is deteriorated. Therefore, the reactor 15 is provided for the purpose of improving the power factor. Then, the peak value of the current waveform is lowered, and the energized section extends backward. As a result, the power factor is improved.

  Further, a switching control unit 43 that performs control to short-circuit or open the switching unit 19 in synchronization with the zero cross point detected by the zero cross detection unit 29 is provided, and the switching control unit 43 uses the zero cross point of the AC power supply 13 as a reference. In order to improve the power factor, the switching unit 19 is short-circuited for an appropriate time width at an appropriate time.

  If power factor is improved, this contributes to reducing the equipment burden on the supplier of AC power supply 13, and also uses the capacity of breaker or outlet to which DC power supply 11A is connected to the upper limit. This is because the cost performance of the user can be substantially improved by maximizing the capability of the DC power supply device 11A.

  However, it is not only necessary to short-circuit the dark clouds. Depending on the short-circuiting method and load conditions, the harmonic current may increase on the contrary.

  In this regard, according to the study by the present inventors, the DC voltage is raised to a value exceeding √2 * Vs (the effective value of the AC input voltage) while improving the power factor and reducing the harmonic current. It has been found that the switching unit 19 needs to be short-circuited four or more times within the period of the power supply voltage half cycle. Then, it is required to determine the short-circuit timing (short-circuit start time) and the short-circuit time width based on the constraint condition of the number of short-circuits.

  However, how to determine the short-circuit timing (short-circuit start time) and the short-circuit time width is a very difficult problem.

Therefore, in the present invention, a configuration is adopted in which the short-circuit timing is determined for each pulse and the short-circuit time width is determined by calculating the duty D thereof.
Here, the short-circuit timing for each pulse (short-circuit start time; time information on the time axis until the short-circuit is started with the zero cross (start point) of the half cycle of the power supply voltage as the origin) is td, and the short-circuit time width (pulse on-time) ) Is defined as ton, and the time width from the end of the short circuit to the short circuit timing of the next pulse (pulse off time) is defined as toff.

(Duty D calculation method)
Next, a method for calculating the duty D will be described.
First, it is assumed that the input current is is, the AC input voltage is vs, the inductance value of the reactor 15 is L, and the DC output voltage is Vd. Then, the differential ion ′ of the input current when the switching unit 19 is short-circuited (ON) can be expressed as (Equation 1). Further, the differential ioff ′ of the input current when the switching unit 19 is turned off can be expressed as (Equation 2).
ion '= dis / dt = vs / L (Formula 1)
ioff ′ = dis / dt = (vs−Vd) / L (Expression 2)

When the time width for short-circuiting (ON) the switching unit 19 is ton and the time width for opening (OFF) the switching portion 19 is toff, the duty D can be expressed as (Equation 3).
D = ton / (ton + toff) (Formula 3)

The value obtained by taking into account the duty D of the input current differential ion 'when the switching unit 19 is short-circuited (ON) and the input current differential ioff' when the switching unit 19 is opened (OFF). Assuming that it is equal to ', (Equation 4) holds. When the duty D is obtained from (Equation 4), (Equation 5) is established.
is ′ = D · ion ′ + (1−D) · ioff ′ (Formula 4)
D = (is′−ioff ′) / (ion′−ioff ′) (Formula 5)

If the AC input voltage vs is given, ion ′ and ioff ′ can be obtained using (Expression 1) and (Expression 2).
Here, the AC input voltage vs can be expressed as (Equation 6) using the power supply frequency f acquired from the frequency calculation unit 41 and the AC voltage effective value Vs acquired from the input voltage acquisition unit 25. .
vs = √2 · Vs · sin (2πft) (Expression 6)

Further, the instantaneous input current is can be expressed as (Equation 7) using the input current effective value Is acquired from the input current acquisition unit 27. Taking the derivative, (Equation 8) is obtained.
is = √2 · Is · sin (2πft) (Expression 7)
is ′ = 2√2 · πf · Is · cos (2πft) (Equation 8)

  Therefore, by substituting the solutions of (Equation 1), (Equation 2), and (Equation 8) into (Equation 5), the duty D for making the input current is close to a sine wave can be obtained by calculation.

  If the half-cycle of the power supply voltage is divided in advance by the number of short circuits, and the divided short time width is multiplied by the duty D to determine the short circuit (on) time width ton, the input current is having a high power factor is obtained. be able to.

(How to divide and how to determine the short-circuit (on) time width ton and the open (off) time width toff)
Next, a method of determining the short-circuit (on) time width ton will be described by exemplifying a case where the short-circuit operation is performed eight times in the power supply voltage half cycle.

The short-circuit timing td related to the nth pulse is td (n), the short-circuit time width (pulse on-time) related to the nth pulse is ton (n), and the time from the end of the short-circuit related to the nth pulse to the short-circuit timing of the next pulse The width (pulse off time) is toff (n).
Note that td (1) needs to be adjusted so that it takes an appropriate value in consideration of improvement of the power factor and suppression of harmonic current. Here, td (1) = 0.5 ms.

  For example, when the power supply frequency f is 50 Hz, ton (1) + toff (1) of the first pulse is set to be as long as 2 ms because it is necessary to flow a large current in order to make is close to the theoretical sine wave. A common value (0.8 ms) is set for ton (n) + toff (n) of the second to seventh pulses thereafter.

Then, a set of time td (n) (unit: ms) from the zero cross to the short circuit start can be expressed as (Equation 9). However, n = 1-8.
(Td (1), td (2), td (3), td (4), td (5), td (6), td (7), td (8))
= (0.5, 2.5, 3.3, 4.1, 4.9, 5.7, 6.5, 7.3) (Equation 9)

  If the current flowing through the load is 14A and the target DC output voltage is 300V, the duty D can be expressed as shown in FIG. 2A using (Equation 5). FIG. 2A is a diagram showing the pulse duty D and the input current theoretical waveform at a power supply frequency of 50 Hz.

  If the center value of ton (n) + toff (n) is multiplied by the duty D, the short-circuit time width ton (n) for the nth pulse can be obtained by calculation. FIG. 2B shows an input current waveform and a DC output voltage waveform when a simulation is performed at a power supply frequency of 50 Hz using the thus obtained ton (n).

  In the example shown in FIG. 2B, the power factor was as high as 98.1%, and the harmonic margin was 11%. When this harmonic margin is evaluated, it can be considered as follows. That is, the order in which the harmonic margin is 11% is the 25th order. As for the orders after the 21st order, if the partial odd harmonic current is 100% or less, 150% or less of the applicable limit value is satisfied. Here, the margin of the partial odd harmonic current is 49.3%. Therefore, considering that the 25th order is 150% or less of the applicable limit value, the harmonic margin is 61%, and it can be seen that the harmonic margin is sufficiently large.

  The control method of the DC power supply device 11A according to the first embodiment is particularly effective when used in a case where a DC output voltage of √2 Vs or more is required in combination with conventional converter control.

On the other hand, when the power supply frequency f is 60 Hz, the set of time td (n) (unit: ms) from the zero cross to the start of the short circuit may be 5/6 of (Equation 9). This is expressed in (Equation 10).
(Td (1), td (2), td (3), td (4), td (5), td (6), td (7), td (8)) = (0.42, 2.08 , 2.75, 3.42, 4.08, 4.75, 5.41, 6.08) (Equation 10)

  If the current flowing through the load is 14 A and the target DC output voltage is 300 V, the duty D can be expressed as shown in FIG. 3A using (Equation 5). FIG. 3A is a diagram showing the pulse duty D and the input current theoretical waveform at a power supply frequency of 60 Hz.

  If the center value of ton (n) + toff (n) is multiplied by the duty D, the short-circuit time width ton (n) for the nth pulse can be obtained by calculation. FIG. 3B shows an input current waveform and a DC output voltage waveform when a simulation is performed at a power supply frequency of 60 Hz using the thus obtained ton (n).

  In the example shown in FIG. 3B, the power factor was as high as 97.7% and the harmonic margin was 43%. However, the DC output voltage Vd was 314 V, and the input current effective value Is was 14.89 A, which was larger than the duty D obtained by calculation using (Equation 5). Such an error is considered to be caused by the fact that the DC output voltage Vd and the input current effective value Is increased but the number of pulses is small, and that the DC output voltage Vd is constant in (Equation 5).

  Several measures can be taken to eliminate these errors. The first countermeasure is to feed back the value of the DC output voltage Vd and apply a certain coefficient to the duty D calculated using (Equation 5). The second countermeasure is to feed back the value of the DC output voltage Vd and change the voltage used in (Equation 5). A third countermeasure is to change the inductance value L of the reactor 15 used in (Equation 5) by feeding back the value of the DC output voltage Vd.

  As described above, according to the DC power supply device 11A according to the first embodiment, within the range of 4 pulses to 40 pulses, even if the power supply frequency f is 50 Hz or 60 Hz, efficiency improvement, power factor improvement, In addition, the high frequency problem can be solved at a high level.

[Second Embodiment]
Next, the overall configuration of the DC power supply device 11B according to the second embodiment will be described with reference to FIG. FIG. 4 is a block diagram showing a circuit configuration of a DC power supply device 11B according to the second embodiment of the present invention.
Note that the DC power supply device 11A according to the first embodiment and the DC power supply device 11B according to the second embodiment share most of the components. For this reason, members having common functions are denoted by the same reference numerals in principle, and redundant explanations are omitted, and the explanation will be made focusing on the differences between the two.

  The difference between the first embodiment and the second embodiment is that the acquisition path of the inductance value L of the reactor 15 is different. That is, the DC power supply device 11A according to the first embodiment includes an inductance storage unit 37 as shown in FIG. 1, and the converter control unit 35 acquires the inductance value L of the reactor 15 via the inductance storage unit 37. The configuration is adopted.

  On the other hand, as shown in FIG. 4, the DC power supply device 11 </ b> B according to the second embodiment includes the inductance estimation unit 38, and the converter control unit 35 calculates the inductance value L of the reactor 15 via the inductance estimation unit 38. The configuration to acquire is adopted.

  The inductance estimation unit 38 includes an input voltage effective value Vs of the AC power supply 13 acquired by the input current acquisition unit 25, an input current effective value Is from the AC power supply 13 acquired by the input current acquisition unit 27, and a DC output voltage acquisition unit. The inductance value L of the reactor 15 is estimated based on each information including the DC output voltage Vd acquired at 31 and the frequency f of the AC power source calculated by the frequency calculation unit 41.

Specifically, the state where the switching unit 19 is not short-circuited is maintained, and the magnitude of the DC power applied to the load (three-phase inverter circuit 21 and motor 23) is such that the input current is flowing at that time is about 1 to 2A. Adjust so that This adjustment can be performed by adjusting the PWM signal applied to the three-phase inverter circuit 21. At this time, the inductance value L of the reactor 15 can be estimated as (Equation 11).
L = (Vs−Vd / √2) / (2f · Is) (Expression 11)

  In short, the inductance estimation unit 38 may estimate the inductance value L of the reactor 15 using the calculation formula (Formula 11) prior to driving the load (the three-phase inverter circuit 21 and the electric motor 23). This estimated value includes an error because the power factor, DC resistance, forward voltage of the first full-wave rectifier circuit 17a, and the like are not taken into consideration. However, the error that has occurred can be reduced by feeding back the value of the DC output voltage Vd after starting the converter control, as described in the measures for the error of the DC output voltage Vd in the first embodiment. .

  According to the DC power supply device 11B according to the second embodiment, as in the DC power supply device 11A according to the first embodiment, the power supply frequency f is either 50 Hz or 60 Hz within the range of 4 pulses to 40 pulses. However, efficiency improvement, power factor improvement, and elimination of high frequency problems can be realized at a high level.

[Third Embodiment]
Next, the overall configuration of the DC power supply device 11C according to the third embodiment will be described with reference to FIG. FIG. 5 is a block diagram showing a circuit configuration of a DC power supply device 11C according to the third embodiment of the present invention.
Note that the DC power supply device 11A according to the first embodiment and the DC power supply device 11C according to the third embodiment share most of the components. For this reason, members having common functions are denoted by the same reference numerals in principle, and redundant explanations are omitted, and the explanation will be made focusing on the differences between the two.

  The difference between the first embodiment and the third embodiment is that the acquisition path of the input voltage effective value Vs of the AC power supply 13 is different. That is, in the DC power supply device 11A according to the first embodiment, as illustrated in FIG. 1, the input voltage acquisition unit 25 is provided, and the converter control unit 35 receives the input voltage vs of the AC power supply 13 via the input voltage acquisition unit 25. Adopted a configuration to acquire.

  In contrast, the DC power supply device 11C according to the third embodiment includes an input voltage estimation unit 26 corresponding to both the input voltage acquisition unit and the input voltage estimation unit of the present invention, as shown in FIG. The unit 35 employs a configuration that acquires the input voltage vs of the AC power supply 13 via the input voltage estimation unit 26.

The input voltage estimation unit 26 is based on information on the DC output voltage Vd acquired by the DC output voltage acquisition unit 31 before driving the loads (the three-phase inverter circuit 21 and the electric motor 23), and the input voltage effective value Vs of the AC power supply 13 is obtained. Is estimated. The input voltage effective value Vs of the AC power supply 13 can be estimated as (Equation 12).
Vs = Vd / √2 (12)

  This estimated value includes an error because the forward voltage of the first full-wave rectifier circuit 17a is not taken into consideration. However, the error that has occurred can be reduced by feeding back the value of the DC output voltage Vd after starting the converter control, as described in the measures for the error of the DC output voltage Vd in the first embodiment. .

  According to the DC power supply device 11C according to the third embodiment, similarly to the DC power supply devices 11A and 11B according to the first and second embodiments, the power supply frequency f is 50 Hz or 60 Hz within the range of 4 pulses to 40 pulses. In any case, efficiency improvement, power factor improvement, and elimination of high-frequency problems can be realized at a high level.

[Application example of DC power supply devices 11A to 11C according to any of the first to third embodiments]
Next, an air conditioner 51 equipped with a DC power supply device according to any of the first to third embodiments will be described with reference to FIGS. 6 to 8. FIG. 6 is a schematic configuration diagram of an air conditioner 51 equipped with a DC power supply device according to any of the first to third embodiments of the present invention. FIG. 7 is a perspective view showing the internal structure of the outdoor unit 55 of the air conditioner 51. FIG. 8 is a plan view illustrating a state in which the top plate of the outdoor unit 55 is removed.

  As shown in FIG. 6, an air conditioner 51 equipped with the DC power supply device 11 (any one of 11A, 11B, and 11C) according to any of the first to third embodiments includes an indoor unit 53 and an outdoor unit 55. Are connected via a connection pipe 57.

  As shown in FIG. 6, the indoor unit 53 is provided with an indoor heat exchanger (not shown), an indoor blower, a dew tray, and the like attached to the housing 59, and these are covered with a decorative frame 61. A front panel 63 is attached. The decorative frame 61 is provided with an air suction port 65 for sucking room air and an air suction port 67 for blowing air in which the temperature and humidity are harmonized into the room.

  The indoor unit 53 includes a control board in an electrical component box (not shown), and a microcomputer is provided on the control board. The microcomputer receives signals from various sensors such as an indoor temperature sensor and an indoor humidity sensor (not shown), receives an operation signal from the remote controller 69 at the light receiving unit 71, controls the indoor blower, etc. Control the indoor unit 53 in a centralized manner.

  The outdoor unit 55 is mounted with an outdoor heat exchanger 79, a compressor 85, and an outdoor blower (not shown) shown in FIG. 7 on the base 73, and these are covered with an outer casing 75, and the pipe connection valve 77 is connected to the indoor unit. The connection pipe 57 from 53 is connected.

  As shown in FIG. 6, the outer casing 75 of the outdoor unit 55 includes a front plate 75a, a side plate 75b, and a top plate 75c. The outdoor unit 55 has an outdoor air suction portion on the outer surface facing the outdoor heat exchanger 79 (see FIG. 7), and a front plate 75a (see FIG. 6) facing the outdoor fan 81 (see FIG. 7). On the side, fan grills 83 (see FIGS. 6 and 8) that allow air flow are provided.

  As shown in FIGS. 7 and 8, the outdoor fan 81 is rotationally driven so as to create an air flow in which the outdoor heat exchanger 79 is located on the upstream side and the fan grille 83 is located on the downstream side. Accordingly, the outdoor fan 81 operates to forcibly guide outdoor air to the outdoor heat exchanger 79.

  As shown in FIGS. 7 and 8, the outdoor heat exchanger 79 is disposed in a substantially L shape from the side surface to the back surface of the outdoor unit 55. As a result, a large contact area with the air is secured, and the heat exchange capability is enhanced. An outdoor fan 81 having a large diameter as much as possible is used. A partition plate 87 is provided between the outdoor fan 81 and the compressor 85. The partition plate 87 partitions the blower chamber 89 and the machine chamber 91.

  The blower chamber 89 is provided with an outdoor heat exchanger 79 and an outdoor fan 81, respectively. The machine chamber 91 is provided with a compressor 85, an accumulator 93, a refrigerant feed pipe (not shown), and the like.

  Various electric components 97 such as any one of the DC power supply devices 11A to 11C according to the first to third embodiments, the three-phase inverter circuit 21 that drives the electric motor 23 of the compressor 85, and the blower motor 95 are illustrated in FIG. The lid 99 is placed in a state of being housed in the electrical box 98. Thereby, the maintainability of various electrical components 97 is secured.

  When operating the air conditioner 51 configured as described above, the user operates the remote controller 69 to selectively set one of the air conditioning modes of cooling, dehumidification, and heating. For example, when the automatic operation of cooling is selectively set as the air conditioning mode, the microcomputer receives the command to give a control command for performing the automatic cooling operation based on information from various sensors such as a temperature sensor and a humidity sensor. .

  The control unit (not shown) of the outdoor unit 55 that has received a control command from the microcomputer drives the indoor blower in accordance with the control command, and distributes the indoor air from the air suction port 65 to the indoor heat exchanger. The control unit of the outdoor unit 55 controls the compressor 85, the blower motor, the control valve, and the like according to the control command from the microcomputer of the indoor unit 53, and circulates the refrigerant from the compressor 85 to the refrigeration cycle. It operates to circulate outdoor air to the heat exchanger 79.

  As described above, in the application example of the DC power supply devices 11A to 11C according to any of the first to third embodiments, in the air conditioner 51 equipped with the rotation speed control type compressor 85, the first to first The configuration in which any one of the DC power supply devices 11 </ b> A to 11 </ b> C according to the third embodiment is used as the power source of the electric motor 23 that rotationally drives the compressor 85 is adopted.

  When such a configuration is adopted, immediately after the start of operation, the air conditioner 51 is a stage in which the air conditioning is advanced to the vicinity of the set temperature by quickly adjusting the room with high capacity and quickly responding to the user's demand for comfort. However, in order to give an unpleasant feeling to the user when the air-conditioning operation is intermittent, it is required to switch to the continuous operation with a low capacity. For this reason, the air conditioner 51 is strongly required to be able to cope with a wide range of load fluctuations from high capacity to low capacity by making the rotational speed of the compressor 85 variable.

  In this regard, when the DC power supply devices 11A to 11C according to any one of the first to third embodiments are applied to the air conditioner 51, immediately after the start of operation, the interior of the user is air-conditioned with high capacity. When the air conditioning is advanced to the vicinity of the set temperature, it is possible to smoothly switch to continuous operation with a low rotational speed and low capacity at a stage where air conditioning is advanced to near the set temperature.

  Specifically, the number of short circuits of the switching unit 19 is increased at high loads such as immediately after the start of operation. In this case, the DC output voltage Vs is boosted to drive the compressor 85 so that high capacity (the electric motor 23 of the compressor 85 can overcome the induced voltage and rotate at high speed) can be exhibited. At the same time, a high power factor is ensured, and the capacity of the air conditioner 51 is maximized by making full use of the capacity of the breaker connected to the air conditioner 51 or the outlet. Can be.

  In general, in the air conditioner 51, the operation time near the set temperature becomes long. For this reason, an efficient driving | operation with a small switching loss is continued continuously, and the power consumption as a whole can be suppressed. As a result, it is possible to provide the air conditioner 51 that is inexpensive, satisfies the power supply harmonic current regulation, and has a high capacity and uses the power supply capacity to the maximum and has a high efficiency.

[Other Embodiments]
The plurality of embodiments described above show examples of implementation of the present invention. Therefore, the technical scope of the present invention should not be limitedly interpreted by these. This is because the present invention can be implemented in various forms without departing from the gist or main features thereof.

  For example, as an application example of the DC power supply devices 11A to 11C according to any one of the first to third embodiments, the air conditioner 51 including the rotation speed control type compressor 85 is illustrated and described. Is not limited to this example. The DC power supply devices 11A to 11C according to any of the first to third embodiments can be applied to a wide range of electronic devices using the DC power supply device.

11A DC power supply apparatus according to first embodiment 11B DC power supply apparatus according to second embodiment 11C DC power supply apparatus according to third embodiment 13 AC power supply 15 reactor 17a, 17b First and second full-wave rectifier circuits (rectifiers) circuit)
19 Switching part 21 Three-phase inverter circuit (load)
23 Electric motor (load)
25 Input voltage acquisition unit 26 Input voltage estimation unit (input voltage acquisition unit)
27 Input current acquisition unit 27a Current sensor (input current acquisition unit)
29 Zero Cross Detection Unit 31 DC Output Voltage Acquisition Unit 33 Control Circuit 35 Converter Control Unit 37 Inductance Storage Unit 38 Inductance Estimation Unit 39 Short Circuit Timing Storage Unit 41 Frequency Calculation Unit 43 Switching Control Unit 45 Inverter Control Unit 47 PWM Output Unit 49 Inverter Driver 51 Air conditioner 53 Indoor unit 55 Outdoor unit 57 Connection piping 85 Compressor C1 Smoothing capacitor D1 to D4 First to fourth rectifier diodes D5 to D8 Fifth to eighth rectifier diodes Nd1 to Nd4 First to fourth connections Point PL Positive DC bus NL Negative DC bus

Claims (6)

A rectifier circuit that converts AC power from an AC power source into DC power;
A reactor connected to the rectifier circuit;
A switching unit that short-circuits the AC power supply via the reactor;
An input current acquisition unit for acquiring current from the AC power supply;
An input voltage acquisition unit for acquiring the voltage of the AC power supply;
A zero-cross detector for detecting a zero-cross point of the AC power supply;
A frequency calculation unit for calculating the frequency of the AC power supply;
A DC output voltage acquisition unit for acquiring a DC output voltage of the rectifier circuit;
A short circuit timing storage unit for storing a short circuit timing of the switching unit;
A switching control unit that performs control to short-circuit or open the switching unit in synchronization with the zero-cross point detected by the zero-cross detection unit,
The switching control unit is a short circuit timing stored in the short circuit timing storage unit, the DC output voltage acquired by the DC output voltage acquisition unit, the voltage of the AC power source acquired by the input voltage acquisition unit, and Based on the information on the current from the AC power source acquired by the input current acquisition unit, determine the short-circuit time width of the switching unit,
A direct current power supply device. The DC power supply device according to claim 1,
A smoothing capacitor for smoothing the output of the rectifier circuit and supplying power to the load;
The input voltage acquisition unit acquires the voltage of the AC power supply based on information on the DC output voltage acquired by the DC output voltage acquisition unit before driving the load.
A direct current power supply device. The DC power supply device according to claim 1 or 2,
An inductance storage unit for storing the inductance value of the reactor;
The switching control unit determines the short-circuit time width of the switching unit, taking into account the inductance value of the reactor stored in the inductance storage unit,
A direct current power supply device. The DC power supply device according to claim 1 or 2,
An inductance estimation unit for estimating the inductance value of the reactor;
The inductance estimator is a voltage of the AC power source acquired by the input current acquisition unit, a current from the AC power source acquired by the input current acquisition unit, a DC output voltage acquired by the DC output voltage acquisition unit, and , Based on each information including the frequency of the AC power source calculated by the frequency calculation unit, to estimate the inductance value of the reactor,
The switching control unit determines the short-circuit time width of the switching unit in consideration of the inductance value of the reactor estimated by the inductance estimation unit,
A direct current power supply device. The DC power supply device according to any one of claims 1 to 4,
The switching control unit performs control to short-circuit the switching unit 4 to 40 times within a period of a power supply voltage half cycle.
A direct current power supply device. In an air conditioner equipped with a rotational speed control type compressor,
The DC power supply device according to any one of claims 1 to 5 is used as a power source for an electric motor that rotationally drives the compressor.
An air conditioner characterized by that.

Images