阅读说明：本技术 空调装置 (Air conditioner ) 是由 田中七海 关本守满 小川卓郎 林伸夫 于 2020-04-09 设计创作，主要内容包括：在空调装置中,功率转换装置(10)的控制部(40)控制开关动作,以使向功率转换装置(10)输入的输入电流(is)具有非导通期间。控制部(40)控制开关动作,以使在所述空调装置的最大条件下,相对于输入电流(i-(s))中所包含的基波的五次谐波的相位在90°以上且270°以下的范围内,并且(五次谐波的振幅)/(基波分量的振幅)的值即振幅比小于空调装置的额定条件下的振幅比。(In an air conditioner, a control unit (40) of a power conversion device (10) controls a switching operation so that an input current (is) input to the power conversion device (10) has a non-conduction period. The control unit (40) controls the switching operation so that the input current (i) is controlled to be equal to the maximum input current (i) under the maximum condition of the air conditioner s ) The phase of the fifth harmonic of the fundamental wave included in (b) is in a range of 90 ° to 270 °, and the amplitude ratio, which is the value of (amplitude of the fifth harmonic)/(amplitude of the fundamental wave component), is smaller than the amplitude ratio under the rated condition of the air conditioner.)

1. An air conditioning apparatus, characterized in that: the air conditioning apparatus includes:

a motor (30);

a power conversion device (10) that supplies power to the electric motor (30); and

a control unit (40) for controlling the power conversion device (10),

the power conversion apparatus (10) includes:

an AC/DC conversion circuit (11), wherein the AC/DC conversion circuit (11) rectifies an AC voltage of a single-phase AC power supply (20);

a DC link unit (12) having a capacitor (C), wherein the DC link unit (12) generates a DC voltage (v) pulsating in accordance with the frequency of the AC voltage, using the output of the AC/DC conversion circuit (11) as an input_dc) (ii) a And

a DC-AC conversion circuit (13), the DC-AC conversion circuit (13) having a plurality of switching elements (Su, Sv, Sw, Sx, Sy, Sz),

the capacitance value of the capacitor (C) is set such that the DC voltage (v) is at the maximum condition of the air conditioner_dc) Is said direct voltage (v)_dc) More than twice as small as the minimum value of (c),

the DC/AC conversion circuit (13) converts the DC voltage (v) by switching the switching elements (Su, Sv, Sw, Sx, Sy, Sz)_dc) Converted into an alternating voltage of a predetermined frequency and output to the motor (30),

the control unit (40) controls the switching operation so that the input current (i) to the power conversion device (10) is input_s) Has a non-conduction period, and a non-conduction period,

the control unit (40) controls the switching operation so that the input current (i) is controlled to be the maximum value under the maximum condition of the air conditioner_s) The phase of the fifth harmonic of the fundamental wave included in (b) is in a range of 90 ° to 270 °, and an amplitude ratio, which is a value of (amplitude of the fifth harmonic)/(amplitude of the fundamental wave component), is smaller than the amplitude ratio under a rated condition of the air conditioner.

2. An air conditioning apparatus according to claim 1, characterized in that:

the control unit (40) controls the switching operation so that: for the input current (i) in the power supply half cycle_s) The waveform of (2) includes two or more maximum points under the rated condition, and the waveform obtained by multiplying the waveform obtained by extracting the fundamental wave, the third harmonic, and the fifth harmonic and combining the extracted fundamental wave, the third harmonic, and the fifth harmonic by the polarity of the voltage of the alternating-current power supply (20) has one maximum point under the maximum condition.

3. An air conditioning apparatus according to claim 1, characterized in that:

the control unit (40) controls the switching operation so that the amplitude ratio is 50% or more of the amplitude ratio under the rated condition under the maximum condition.

4. An air conditioning apparatus according to any one of claims 1 to 3, characterized in that:

the control unit (40) controls the switching operation so that the amplitude ratio is 9% or more under the rated condition.

5. An air conditioning apparatus according to any one of claims 1 to 3, characterized in that:

the control unit (40) controls the switching operation so that the amplitude ratio is 4% or more under the maximum condition.

6. An air conditioning apparatus according to any one of claims 1 to 5, characterized in that:

the control unit (40) controls the switching operation so that the amplitude ratio is reduced in accordance with the magnitude of the input power of the power conversion device (10).

Technical Field

The present disclosure relates to an air conditioner.

Background

In some power conversion devices, a capacitor having a small capacitance is provided in a dc link section to improve a power factor (see, for example, patent document 1).

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2002-51589

Disclosure of Invention

Technical problems to be solved by the invention

In the example of patent document 1, there is a tendency that: if power is supplied to the motor by the power conversion device, the effective value of the motor current increases and the efficiency of the motor decreases.

The purpose of the present disclosure is: the suppression of the effective value of the motor current and the suppression of the harmonic current contained in the power supply current are achieved in a balanced manner.

Technical solution for solving technical problem

A first aspect of the present disclosure is an air conditioning apparatus characterized in that: an air conditioning device includes:

a motor 30;

a power conversion device 10 that supplies power to the motor 30; and

a control unit 40 for controlling the power conversion device 10,

the power conversion apparatus 10 includes:

an ac/dc conversion circuit 11, the ac/dc conversion circuit 11 rectifying an ac voltage of a single-phase ac power supply 20;

a DC link part 12, the DC link part 12 having a capacitor C and connecting the AC line and the DC lineThe output of the dc converter circuit 11 is used as an input to generate a dc voltage v pulsating in accordance with the frequency of the ac voltage_dc(ii) a And

a DC-AC conversion circuit 13, the DC-AC conversion circuit 13 having a plurality of switching elements Su, Sv, Sw, Sx, Sy, Sz,

the capacitance value of the capacitor C is set so that the DC voltage v is set to be the maximum value of the air conditioner_dcIs said direct voltage v_dcMore than twice as small as the minimum value of (c),

the dc/ac conversion circuit 13 converts the dc voltage v by switching the switching elements Su, Sv, Sw, Sx, Sy, Sz_dcConverted into an alternating voltage of a predetermined frequency and output to the motor 30,

the control unit 40 controls the switching operation so that the input current i to the power conversion device 10 is input_sHas a non-conduction period, and a non-conduction period,

the control unit 40 controls the switching operation so that the input current i is equal to the maximum condition of the air conditioner_sThe phase of the fifth harmonic of the fundamental wave included in (b) is in a range of 90 ° to 270 °, and an amplitude ratio, which is a value of (amplitude of the fifth harmonic)/(amplitude of the fundamental wave component), is smaller than the amplitude ratio under a rated condition of the air conditioner.

In the first aspect, the operation with importance placed on the efficiency of the air conditioner 1 and the suppression of the power supply current i are performed in accordance with the power_sThe operation of higher harmonics. In the present embodiment, suppression of the effective value of the motor current and suppression of the harmonic current included in the power supply current can be achieved in a balanced manner.

An air conditioning apparatus according to a second aspect of the present disclosure is the air conditioning apparatus according to the first aspect, characterized in that:

the control unit 40 controls the switching operation so that: for the input current i in the power supply half cycle_sThe waveform of (a) is obtained by multiplying a waveform obtained by extracting a fundamental wave, a third harmonic wave and a fifth harmonic wave and combining the extracted waveform and the fifth harmonic wave by the polarity of the voltage of the ac power supply 20The waveform includes two or more maximum points under the rated condition, and one maximum point exists under the maximum condition.

In the second aspect, the suppression of the effective value of the motor current is mainly performed under the rated condition, and the suppression of the harmonic current is mainly performed under the maximum condition.

An air conditioning apparatus according to a third aspect of the present disclosure is the air conditioning apparatus according to the first aspect, characterized in that:

the control unit 40 controls the switching operation so that the amplitude ratio is 50% or more of the amplitude ratio under the rated condition under the maximum condition.

In the third aspect, the suppression of the effective value of the motor current is performed under the rated condition and the maximum condition.

An air conditioning apparatus according to a fourth aspect of the present disclosure is the air conditioning apparatus according to any one of the first to third aspects, characterized in that:

the control unit 40 controls the switching operation so that the amplitude ratio is 9% or more under the rated condition.

In the fourth aspect, the suppression of the effective value of the motor current is reliably performed under the rated condition.

An air conditioning apparatus according to a fifth aspect of the present disclosure is the air conditioning apparatus according to any one of the first to third aspects, characterized in that:

the control unit 40 controls the switching operation so that the amplitude ratio is 4% or more under the maximum condition.

In the fifth aspect, the suppression of the effective value of the motor current is reliably performed under the maximum condition.

An air conditioning apparatus according to a sixth aspect of the present disclosure is the air conditioning apparatus according to any one of the first to fifth aspects, characterized in that:

the control unit 40 controls the switching operation so that the amplitude ratio is reduced in accordance with the magnitude of the input power of the power converter 10.

In the sixth aspect, the effective value of the motor current is suppressed at an operating point other than the rated condition and the maximum condition.

Drawings

FIG. 1 is a piping diagram of an air conditioning unit;

fig. 2 is a block diagram showing the configuration of a power conversion apparatus;

FIG. 3 shows an example of waveforms of a power supply voltage and a DC voltage;

FIG. 4 exemplarily illustrates a first waveform;

FIG. 5 schematically illustrates a second waveform;

fig. 6 exemplarily shows a synthesized waveform of the first waveform and the second waveform;

fig. 7 is a graph showing a relationship between an effective value of a motor current and THD (described later);

fig. 8 is a graph showing a relationship between a value of (amplitude of the n-th harmonic)/(amplitude of the fundamental component) and THD (described later);

FIG. 9 illustrates in waveform the values of the dq-axis current parameters referred to in the first table;

fig. 10 shows the relationship between the phase of the fifth harmonic and the effective value of the motor current;

fig. 11 illustrates a current absolute value waveform in the case where the first table is used;

FIG. 12 illustrates in waveform the values of the dq-axis current parameters referred to in the second table;

fig. 13 illustrates a current absolute value waveform in the case where the second table is used;

fig. 14 illustrates dq-axis current parameters (Pq, Pd) in the case where the arithmetic mean values of the first table and the second table are used;

fig. 15 illustrates a current absolute value waveform in the case where the arithmetic average values of the first table and the second table are used;

fig. 16 is a diagram showing a relationship between an effective value of a motor current and an amplitude ratio under a rated condition;

fig. 17 is a diagram showing a relationship between an effective value of a motor current and an amplitude ratio in a maximum condition;

fig. 18 shows a relationship between the scale upper limit value and the amplitude ratio.

Detailed Description

(embodiment mode)

An example of an air conditioner that cools and heats a room will be described as an embodiment. Fig. 1 is a piping system diagram of an air conditioner 1. As shown in fig. 1, the air conditioner 1 includes a power conversion device 10, a control unit 40, and a refrigerant circuit 110.

Refrigerant circuit

The refrigerant circuit 110 is a closed circuit filled with refrigerant. The refrigerant circuit 110 is provided with a compressor 120, a four-way selector valve 130, an outdoor heat exchanger 140, an expansion valve 150, and an indoor heat exchanger 160.

The compressor 120 can employ various compressors. As an example of the compressor 120, a scroll compressor, a rotary compressor, or the like can be given. The compressor 120 includes a motor 30. The Motor 30 is, for example, an IPM Motor (internal Permanent Magnet Motor). Three-phase ac power is supplied from the power conversion device 10 to the motor 30.

The outdoor heat exchanger 140 is a heat exchanger that exchanges heat between outdoor air and refrigerant. The indoor heat exchanger 160 is a heat exchanger that exchanges heat between indoor air and refrigerant. The expansion valve 150 is a so-called electronic expansion valve.

The four-way selector valve 130 is a valve having first to fourth ports. The four-way selector valve 130 is switchable between a first state (shown in solid lines in fig. 1) and a second state (shown in broken lines in fig. 1). In the first state, the first port is communicated with the third port, and the second port is communicated with the fourth port. In the second state, the first valve port is communicated with the fourth valve port, and the second valve port is communicated with the third valve port.

In the refrigerant circuit 110, the discharge port of the compressor 120 is connected to the first port of the four-way selector valve 130, and the suction port is connected to the second port of the four-way selector valve 130. In the refrigerant circuit 110, an outdoor heat exchanger 140, an expansion valve 150, and an indoor heat exchanger 160 are arranged in this order from the third port to the fourth port of the four-way selector valve 130. In the air conditioning apparatus 1, the four-way selector valve 130 is switched between the cooling operation and the heating operation.

Power conversion device

Fig. 2 is a block diagram showing the configuration of the power conversion apparatus 10. As shown in fig. 2, the power converter 10 includes an ac/dc converter circuit 11, a dc link unit 12, and a dc/ac converter circuit 13. The power conversion device 10 converts a voltage (hereinafter referred to as a power supply voltage v) supplied from a single-phase ac power supply 20 into a voltage_in) Converted into a predetermined alternating voltage. The power converter 10 supplies the motor 30 with the ac voltage converted as described above.

The ac/dc conversion circuit 11 includes four diodes D1, D2, D3, and D4 connected in a bridge shape. The ac/dc conversion circuit 11 is connected to an ac power supply 20 through a reactor L. AC/DC conversion circuit 11 for power supply voltage v_inFull-wave rectification is performed.

The dc link section 12 has a capacitor C. The capacitor C is connected to an output node of the ac/dc conversion circuit 11. The capacitance value of the capacitor C is a value that can hardly smooth the output of the ac/dc converter circuit 11. On the other hand, the capacitance value of the capacitor C is set to suppress ripple voltage (voltage variation corresponding to the switching frequency) caused by switching operation (described later) in the dc-ac conversion circuit 13.

Specifically, the capacitor C is a small-capacity capacitor having a capacitance value about 0.01 times that of a smoothing capacitor (for example, an electrolytic capacitor) used in smoothing the output of the ac/dc converter circuit in a general power converter. The capacitance value of the capacitor C is, for example, about several tens of μ F. In this example, a film capacitor is used as the capacitor C.

As described above, in the dc link section 12, the output of the ac/dc conversion circuit 11 is hardly smoothed. As a result, a voltage (hereinafter referred to as a dc voltage v) between terminals of the capacitor C_dc) Residual and supply voltage v_inCorresponding to the frequency of (a). In other words, the dc link section 12 generates the ac voltage (power supply voltage v)_in) Of the frequency of (3) and a pulsating direct voltage v_dc。

FIG. 3 shows the supply voltage v_inWaveform and direct current voltage ofv_dcAn example of the waveform of (1). In this example, the pulsating component has a supply voltage v_inIs twice the frequency of (a). Direct voltage v_dcPulsing in such a way that its maximum value is more than twice its minimum value.

The dc-ac conversion circuit 13 has six switching elements Su, Sv, Sw, Sx, Sy, Sz and six freewheeling diodes Du, Dv, Dw, Dx, Dy, Dz. The switching elements Su, Sv, Sw, Sx, Sy, Sz are connected to each other in a bridge shape. In detail, the dc-ac conversion circuit 13 includes three switch legs (switching legs).

Each switch arm is formed by connecting two switching elements in series. For each of the three switching arms, a midpoint between the switching element Su, Sv, Sw of the upper arm and the switching element Sx, Sy, Sz of the lower arm is connected to a coil (not shown) of each phase (u-phase, v-phase, w-phase) of the motor 30. Each of the switching elements Su, Sv, Sw, Sx, Sy, Sz is connected in inverse parallel with one freewheeling diode Du, Dv, Dw, Dx, Dy, Dz, respectively.

An input node of the dc-ac conversion circuit 13 is connected to both ends of the capacitor C of the dc link section 12. In the dc/ac conversion circuit 13, the switching elements Su, Sv, Sw, Sx, Sy, Sz perform switching operations (ON and OFF operations) to convert the dc voltage v into the dc voltage v_dcConverted into a predetermined alternating voltage (three phases). The dc/ac conversion circuit 13 supplies the ac voltage (three phases) converted as described above to the motor 30.

Control section

The control unit 40 controls the switching operation in the dc/ac conversion circuit 13 so that the rotation speed ω of the motor 30 converges on the given command value (hereinafter referred to as a rotation speed command value ω)^*). In other words, the control unit 40 controls the output voltage of the dc/ac conversion circuit 13.

The control unit 40 includes a microcomputer and a storage device storing software for operating the microcomputer. By executing the software by the microcomputer, the control unit 40 functions as a speed control unit 41, a current command calculation unit 42, a coordinate conversion unit 43, a dq-axis current control unit 44, a PWM calculation unit 45, a compensation amount calculation unit 47, a dq-axis current parameter selection unit 48, a dq-axis current command calculation unit 49, a harmonic parameter selection unit 50, and an adder 51 (see fig. 2).

The speed control unit 41 generates a command value of the average motor torque Tm (hereinafter referred to as an average torque command value Tm). Specifically, the speed control unit 41 controls the rotation speed ω of the motor 30 based on the rotation speed ω and the rotation speed command value ω^*For example, PID calculation (proportional, integral, differential) is performed to generate an average torque command value Tm. The speed control unit 41 outputs the average torque command value Tm to the dq-axis current command calculation unit 49.

The dq-axis current parameter selection unit 48 generates a d-axis current command value i_d ^*And a parameter for generating a q-axis current command value i (hereinafter referred to as a d-axis current parameter Pd)_q ^*Is measured (hereinafter referred to as q-axis current parameter Pq). d-axis current command value i_d ^*Is indicative of d-axis current i of motor 30_dThe instruction value of (2). q-axis current command value i_q ^*Is indicative of the q-axis current i of the motor 30_qThe instruction value of (2).

Hereinafter, the d-axis current parameter Pd and the q-axis current parameter Pq are collectively referred to as dq-axis current parameters Pq, Pd. The dq-axis current parameter selection unit 48 outputs the dq-axis current parameters Pq and Pd to the dq-axis current command calculation unit 49.

The dq-axis current parameter selection unit 48 includes two tables for generating the dq-axis current parameters Pq, Pd. In each table, the value of the power supply phase θ in and the values of the dq-axis current parameters Pq and Pd at the power supply phase θ in are stored in pairs. Each table is configured to output dq-axis current parameters Pq and Pd corresponding to a power source phase θ in, using the power source phase θ in as a parameter.

The dq-axis current parameter selection unit 48 outputs a value read from either one of these tables Tb1 and Tb2 or a value calculated from the values of both tables Tb1 and Tb 2. The contents of these tables Tb1 and Tb2 and the contents of generating dq-axis current parameters Pq and Pd by using tables Tb1 and Tb2 will be described later.

The dq-axis current command calculation unit 49 uses the value obtained by modulating the average torque command value Tm with the dq-axis current parameters Pq and Pd as the d-axis currentInstruction value i_d ^*And outputs the result to the dq-axis current control unit 44. The dq-axis current command calculation unit 49 modulates the value of the average torque command value Tm (hereinafter referred to as command value basic data i) by the q-axis current parameter Pq_q ^**)And outputs to the adder 51.

The power conversion device 10 is provided with a power supply current i_sA non-conducting period. By applying a supply voltage v_inThe parameters α 1 and α 2 are represented by phase angles with reference to the frequency of (a).

The harmonic parameter selection unit 50 outputs the lengths α 1 and α 2 of the non-conduction period and the harmonic parameter i3 to the current command calculation unit 42. The lengths α 1 and α 2 of the non-conduction period and the harmonic parameter i3 are used to determine the current (hereinafter referred to as the input current or the power supply current i) input from the ac power supply 20 to the power conversion device 10_s) The size (amplitude) of the higher harmonic contained in (1). For reasons described in detail below, the higher harmonics are referred to the supply voltage v_inFifth harmonic of the fundamental wave of (1).

The harmonic parameter selection unit 50 sets the lengths α 1 and α 2 of the non-conduction period and the magnitude of the harmonic parameter i3 in accordance with the magnitude of the input power (hereinafter referred to as power supply power Pin) input from the ac power supply 20 to the power conversion device 10. The setting of the lengths α 1 and α 2 of the non-conduction period based on the power supply power Pin and the magnitude of the harmonic parameter i3 will be described later.

The current command calculation unit 42 generates the power supply current i as follows_sCommand value of (d) (hereinafter, referred to as power supply current command value | i)_s ^*|)。

The current command operation unit 42 generates a waveform shown by a solid line (hereinafter referred to as a first waveform) shown in fig. 4. Specifically, the current command calculation unit 42 compresses the frequency θ and the power supply voltage v in the time axis direction_inA sine wave sin θ of equal and maximum amplitude 1, thereby generating a first waveform. The curve shown by the dashed line in fig. 4 is the frequency theta versus the supply voltage v_inSine waves of equal and maximum amplitude of 1.

The current command operation unit 42 compresses the first waveform so that a non-conduction period can be generated immediately after the start point and immediately before the end point of the power supply half cycle (see fig. 4). As shown in fig. 3, the "mains half cycle" is a period of half of the voltage cycle of the ac power supply 20 (the same applies hereinafter). Here, the length of the non-conduction period at the start of the power supply half cycle is α 1. The length of the non-conduction period at the end of the mains half cycle is α 2.α 1 and α 2 are parameters outputted from the harmonic parameter selection unit 50. Fig. 4 illustrates a first waveform in the case where α 1 — α 2 is 20 °. At this time, by having the non-conduction period, the first waveform includes the third harmonic and the fifth harmonic in addition to the fundamental wave component.

During non-conduction period, the DC voltage v can be applied_dcIs maintained at a prescribed value. In detail, at the supply voltage v_inNear the zero cross (zero cross) time, the dc voltage v can be applied_dcAnd maintained at a predetermined value (see fig. 3). If the direct current voltage v is applied_dcWhen the value is maintained at the predetermined value, the d-axis current required for flux weakening control of the motor 30 can be reduced near the zero-crossing time. In other words, in the air conditioner 1, the effective value of the motor current can be reduced.

The current command operation unit 42 generates a waveform (hereinafter referred to as a second waveform) shown by a solid line in fig. 5. Specifically, the current command calculation unit 42 compresses the frequency in the time axis direction to the power supply voltage v_inA sine wave having a frequency 3 θ three times as high and a maximum amplitude equal to the harmonic parameter i3, thereby generating a second waveform. The curve shown in fig. 5 with a dashed line is for a supply voltage v_inA sine wave with a frequency 3 theta three times higher and a maximum amplitude equal to the harmonic parameter i 3.

The current command operation unit 42 compresses the second waveform so that a non-conduction period can be generated immediately after the start point and immediately before the end point of the power supply half cycle (see fig. 5). Here, the length of the non-conduction period at the start of the power supply half cycle is α 1. The length of the non-conduction period at the end of the mains half cycle is α 2. Fig. 5 exemplarily shows a second waveform in the case where α 1 — α 2 is 20 ° and the higher harmonic parameter i3 is 0.3. At this time, by having the non-conduction period, the second waveform includes the fifth harmonic in addition to the third harmonic.

The current command operation unit 42 adds the first waveform and the second waveform to generate a synthesized waveform. Fig. 6 exemplarily shows the synthesized waveform. The current command operation unit 42 calculates the effective value of the synthesized waveform and the power supply current i_sEffective value of i_{s_avg}The deviation between the waveforms is calculated by, for example, PI calculation (proportional and integral) to obtain a magnification, and a waveform (hereinafter referred to as a third waveform) obtained by multiplying the synthesized waveform by the magnification is generated. Since the first and second waveforms contain fifth harmonics, the third waveform also contains fifth harmonics. The current command calculation unit 42 outputs the sum of the output current and the power supply voltage v to the compensation amount calculation unit 47_inThe amplitude value of the third waveform corresponding to the phase (power supply phase θ in) of (b).

The compensation amount calculating section 47 calculates the basic data i of the command value_q ^**Is (hereinafter referred to as compensation amount i)_comp ^*) So that the power supply current command value | i_s ^*L and supply current i_sThe deviation of the absolute value of (a) becomes small. The compensation amount calculating section 47 calculates the compensation amount based on the power supply current command value | i_s ^*L and supply current i_sFor example, PI calculation (proportional, integral) is performed to obtain the compensation amount i_comp ^*. The compensation amount calculation unit 47 calculates the compensation amount i_comp ^*And outputs to the adder 51.

Adder 51 adds instruction value basic data i_q ^**And a compensation amount i_comp ^*And (4) adding. The adder 51 takes the addition result as a q-axis current command value i_q ^*And outputs the result to the dq-axis current control unit 44.

The coordinate conversion unit 43 performs so-called dq conversion to derive a d-axis current i of the motor 30_dAnd q-axis current i_q. The coordinate conversion unit 43 uses the u-phase current iu and the w-phase current iw and an electrical angle (motor phase θ m) of a rotor (not shown) of the motor 30 when dq conversion is performed. For example, the values of the u-phase current iu and the w-phase current iw can be detected by providing current sensors.

The dq-axis current control unit 44 controls the d-axis current according to the d-axisCurrent command value i_d ^*Q-axis current command value i_q ^*D axis current i_dAnd q-axis current i_qDeriving a d-axis voltage command value v_d ^*And q-axis voltage command value v_q ^*. Specifically, the dq-axis current control unit 44 derives a d-axis voltage command value v_d ^*And q-axis voltage command value v_q ^*So that the d-axis current command value i_d ^*And d-axis current i_dDeviation between the q-axis current command value and the q-axis current i_qThe deviation therebetween is reduced, respectively.

The PWM calculation unit 45 generates a signal (hereinafter, referred to as a control signal G) for controlling on and off of the switching elements Su, Sv, Sw, Sx, Sy, Sz. In this example, the PWM computing unit 45 calculates the dc voltage v based on the motor phase θ m_dcD-axis voltage command value v_d ^*Q-axis voltage command value v_q ^*D-axis voltage v_dAnd q-axis voltage v_qThe duty ratio of the control signal G supplied to each of the switching elements Su, Sv, Sw, Sx, Sy, Sz is set.

When the control signal G is output, the switching elements Su, Sv, Sw, Sx, Sy, Sz perform switching operations (on/off operations) at a set duty ratio. PWM operation unit 45 periodically updates control signal G.

Content of watch

If a capacitor of small capacity is used in the dc link section 12, the dc voltage v cannot be absorbed_dcIs measured. If it cannot absorb the DC voltage v_dcIs pulsed, then the supply current i_sAffecting the output of the dc-ac converter circuit 13. In other words, if the supply current i_sIncluding higher harmonics, the effective value of the motor current changes. In the power conversion apparatus 10, at a power supply current i_sContains higher harmonics, thereby reducing the effective value of the motor current.

The inventors of the present application found that if the power supply current i is made to be the same_sThe inclusion of the fifth harmonic can effectively reduce the effective value of the motor current. FIGS. 7 and 8 are views for explaining the present inventionUsing the fifth harmonic as the supply current i_sThe reason for the harmonics included in (1) is shown. The vertical axis of fig. 7 is the effective value of the motor current. The horizontal axis of fig. 7 is THD defined by the following formula (1).

[ mathematical formula 1]

In the formula (1), h1 is the power supply current i_sThe fundamental component contained in (a). hn (n is 2, 3, … …) is the supply current i_sThe nth harmonic contained in (1). As shown in fig. 7, as THD increases, the effective value of the motor current decreases.

The horizontal axis of fig. 8 is THD. The vertical axis of FIG. 8 is (supply current i)_sAmplitude of the included n-th harmonic)/(supply current i_sThe amplitude of the included fundamental component). In fig. 8, THD sum (power supply current i) is plotted for n-3 and n-5_sAmplitude of the included n-th harmonic)/(supply current i_sThe amplitude of the included fundamental component). As shown in fig. 8, the supply current i_sThe amplitude of the included fifth harmonic (curve with n-5) monotonically increases with the increase in THD. In other words, with the supply current i_sThe amplitude of the fifth harmonic contained increases and the effective value of the motor current decreases.

As described above, in one of the two tables (hereinafter, referred to as the first table Tb1) included in the dq-axis current parameter selection unit 48, a pair of the value of the power supply phase θ in and the q-axis current parameter Pq is stored so as to obtain the power supply current i including the fifth harmonic_s. Fig. 9 shows values of dq-axis current parameters Pq, Pd generated from the first table Tb1 in waveforms. In fig. 9, the horizontal axis represents the power supply phase θ in. The vertical axis in fig. 9 represents the values of dq-axis current parameters Pq and Pd. As shown in fig. 9, if the q-axis current parameter Pq generated from the first table Tb1 is shown as a waveform, the peak of the sine wave is suppressed (a waveform that is substantially trapezoidal).

To reduce the effective value of the motor current, the supply current i is set_sThe fifth harmonic ofThe phase of the wave is also important. Suppose that: at the supply current i_sWhen the phase of the fundamental wave included in (1) is θ 1 and the phase of the fifth harmonic is θ 5, the power supply current i is used_sThe phase of the fifth harmonic with the phase of the fundamental wave included in (2) as a reference is θ 5 to 5 θ 1. FIG. 10 shows the power supply current i_sThe relationship between the effective value of the motor current and the phases θ 5 to 5 θ 1 of the fifth harmonic with the phase of the fundamental wave included in (b) as a reference. As shown in fig. 10, if the phase is in the range of 90 ° or more and 270 ° or less, the phase is correlated with the power supply current i_sThe effective value of the motor current can be reduced as compared with the case where the fifth harmonic is not included. First table Tb1 of the present embodiment is configured to: with supply current i_sThe phase of the fifth harmonic with respect to the phase of the fundamental wave included in (b) is in a range of 90 ° to 270 °.

In the present embodiment, the power supply current i including the fifth harmonic can be obtained_sIn the embodiment (1), the q-axis current parameter Pq in the first table Tb1 is prepared in advance. The d-axis current parameter Pd of the first table Tb1 is a constant value irrespective of the value of the power supply phase θ in (refer to fig. 9). The first table Tb1 is written in the storage device of the control unit 40, for example, when the air conditioner 1 is manufactured.

As described above, the first table Tb1 is a table in which importance is placed on the effective value for reducing the motor current. In other words, the first table Tb1 is a table in which importance is placed on the efficiency of the air conditioner 1. In the air conditioner 1, if the first table Tb1 is used for control, the slave power supply current i in the power supply half cycle is adjusted_sThe waveform of (a) includes two or more local maximum points (see fig. 11) in a waveform (hereinafter, referred to as a current absolute value waveform for convenience of description) obtained by multiplying a waveform obtained by extracting a fundamental wave, a third harmonic and a fifth harmonic with respect to the fundamental wave and combining the extracted waveforms by the polarity of the voltage of the ac power supply 20. In the air conditioner 1, if the first table Tb1 is used for control, the effective value of the motor current can be suppressed.

Fig. 12 shows dq-axis current parameters Pq and Pd in waveforms generated from another table (hereinafter referred to as a second table Tb 2). In fig. 12, the horizontal axis also represents the power supply phase θ in. The vertical axis in fig. 12 represents the values of dq-axis current parameters Pq and Pd. The second table Tb2 is also written in the storage device of the control unit 40, for example, when the air conditioner 1 is manufactured.

The d-axis current parameter Pd of the second table Tb2 is also a constant value independent of the value of the power supply phase θ in. The q-axis current parameter Pq of the second table Tb2 can also be obtained as the power supply current i containing the fifth harmonic_sThe method of (1) is previously prepared. The second table Tb2 is also formed: with supply current i_sThe phase θ 5-5 θ 1 of the fifth harmonic with respect to the phase of the fundamental wave included in (b) is in a range of 90 ° to 270 °.

The amplitude ratio, which is the value of (the amplitude of the fifth harmonic)/(the amplitude of the fundamental wave component) when power supply Pin is P2 (described later), is smaller than the amplitude ratio, which is the value of (the amplitude of the fifth harmonic)/(the amplitude of the fundamental wave component) when power supply Pin is P1(P1 < P2, described later in detail). Supply current i when power supply Pin is P2_sIs lower than the power supply current i when the power supply power Pin is P1_sMore closely to a sine wave. In the air conditioner 1, if the second table Tb2 is used, one local maximum point is included in the current absolute value waveform (see fig. 13).

In the air conditioner 1, the d-axis current command value i is generated only from the second table Tb2_d ^*Q-axis current command value i_q ^*In the case of (1), the q-axis current command value i is generated only from the first table Tb1_qCommand value of current of x and d axes_d ^*Can suppress the power supply current i more than in the case of_sThe higher harmonics of (1). The second table Tb2 emphasizes the suppression of the power supply current i_sTable of the higher harmonics contained in (1).

Generation of < dq-axis current parameter >

The dq-axis current parameter selection unit 48 generates the dq-axis current parameters Pq and Pd from the power supply power Pin. Specifically, when the power supply power Pin is smaller than P1 (described later), the dq-axis current parameter selection unit 48 reads values from the first table Tb1 and outputs the values as dq-axis current parameters Pq and Pd to the dq-axis current command calculation unit 49. When the power supply power Pin is larger than P2 (where P2 > P1, which will be described in detail later), the dq-axis current parameter selection unit 48 reads values from the second table Tb2 and outputs the values as dq-axis current parameters Pq and Pd to the dq-axis current command calculation unit 49.

When the power supply power Pin is not less than P1 and not more than P2, the dq-axis current parameter selection unit 48 calculates a weighted average of the respective values read from the two tables Tb1 and Tb2, and generates the dq-axis current parameters Pq and Pd. The dq-axis current parameter selection unit 48 outputs the calculated weighted average value to the dq-axis current command calculation unit 49 as the dq-axis current parameters Pq and Pd.

The dq-axis current parameter selection unit 48 calculates a weight for obtaining a weighted average from the ratio (w is a/b) of the difference between the current power supply power Pin and the power P1 (a) to the difference between the power P2 and the power P1 (b). The weight relative to the value of the first table Tb1 is (1-w). The weight relative to the value of the second table Tb2 is w.

The closer the current power supply power Pin is to the power P1, the greater the weight with respect to the values of the first table Tb 1. When the current power supply power Pin is the average value of the power P1 and the power P2, the arithmetic average value of the respective values read from the two tables Tb1 and Tb2 becomes the dq-axis current parameters Pq and Pd as the dq-axis current parameters Pq and Pd. Fig. 14 illustrates dq-axis current parameters Pq, Pd in the case where the arithmetic mean value is used. Fig. 15 illustrates a current absolute value waveform in the case where the arithmetic average value is used.

The power P1 of the present embodiment is the power supply power Pin under the condition that the operating state of the air conditioner 1 is the rated operation (hereinafter referred to as rated condition). The "rated conditions" are defined in the ISO standard as conditions for the test of cooling or heating capacity. Specifically, the rated conditions for the cooling operation are the rated conditions for the cooling capacity test (T1 conditions) of the standard "ISO 5151" Non-reduced air conditioners and heat pumps-Testing and rating "standard. The rated conditions for the heating operation are specified as standard rated conditions for a heating capacity test of standard "ISO 5151" Non-produced air conditioners and heat pressures-Testing and rating ".

In the case of the air conditioner 1 having both the cooling and heating functions, the standard rated condition defined in the cooling capacity test or the standard rated condition defined in the heating capacity test is defined as the "rated condition" of the air conditioner 1. The standard rated conditions specified in the cooling capacity test are used as the "rated conditions", and the standard rated conditions specified in the heating capacity test are used as the "rated conditions", which have no influence. This is because the power supply power Pin under the test conditions is substantially the same under the "rated conditions" in any of the test conditions. On the other hand, when the air conditioner 1 is a dedicated refrigeration machine, the standard rated condition of the refrigeration capacity test is defined as a "rated condition" of the air conditioner 1.

Power P2 in the present embodiment is power supply power Pin under the maximum condition of the capacity of air conditioner 1. The cooling overload condition and the heating low-temperature condition specified in the ISO standard are defined as "maximum conditions". The refrigeration overload conditions define the T1 condition of the refrigeration overload test of the standard "ISO 5151" Non-reduced air conditioners and heat loads-Testing and rating for performance ". The heating low temperature conditions are defined in the standard "ISO 5151" Non-reduced air conditioners and heat pumps-Testing and rating for performance "H2 conditions for the heating capacity test.

In the case of the air conditioner 1 having both the cooling and heating functions, the condition specified in the low temperature condition of the heating capacity test is defined as the "maximum condition" of the air conditioner 1. For example, when the air conditioner 1 is a refrigeration-only machine, the condition of the refrigeration overload test is defined as a "maximum condition". The power supply power Pin under the test conditions is approximately the same regardless of which "maximum condition" of the test conditions is adopted. In other words, whichever test condition is adopted, the "maximum condition" has no influence on the control of the control unit 40.

Generation of higher harmonic parameters

Here, the (supply current i)_sAmplitude of the fifth harmonic contained)/(supply current i_sThe amplitude of the included fundamental component) is defined as an amplitude ratio. The harmonic parameter selection unit 50 adjusts the amplitude ratio in accordance with the magnitude of the power Pin. Hereinafter, the mark amplitude ratio is adopted%And (4) marking. For example, the amplitude ratio of 0.09 is denoted as 9%.

Fig. 16 is a diagram showing a relationship between an effective value of a motor current and an amplitude ratio under a rated condition. Fig. 17 is a diagram showing a relationship between an effective value of the motor current and the amplitude ratio under the maximum condition. In fig. 16 and 17, the abscissa represents the amplitude ratio. In fig. 16 and 17, the vertical axis represents the effective value of the motor current.

As described above, if at the supply current i_sBy superimposing the fifth harmonic, the effective value of the motor current decreases. In the graphs shown in fig. 16 and 17, the slope changes greatly with a certain amplitude ratio as a boundary. If the amplitude ratio exceeds the boundary, the effective value of the motor current is not so reduced even if the amplitude ratio is increased.

The points at which the slope changes are substantially the same whether the rated condition (hereinafter referred to as "cooling rated condition") defined in the above-described cooling capacity test is adopted as the "rated condition" in the graph of fig. 16 or the rated condition (hereinafter referred to as "heating rated condition") defined in the above-described heating capacity test is adopted as the "rated condition" in the graph of fig. 16. Under these nominal conditions, the point at which the slope changes is at an amplitude ratio of 8.3% (9% after carry). In the air conditioner 1, under a rated condition (either of a cooling rated condition and a heating rated condition), if a fifth harmonic is superimposed on the power supply current i at an amplitude ratio of 8.3% or more_sThus, the effective value of the motor current is reliably reduced.

The points at which the slope changes are substantially the same whether the condition of the cooling overload test (hereinafter referred to as the cooling maximum condition) is adopted as the "maximum condition" in the graph of fig. 17 or the condition of the air conditioner 1 (hereinafter referred to as the heating maximum condition) is adopted as the predetermined condition in the low temperature condition of the heating capacity test. Under these maximum conditions, the point at which the slope changes is the amplitude ratio of 3.2% (4% after carry). In the air conditioner 1, under the maximum condition (either one of the cooling maximum condition and the heating maximum condition), if the fifth harmonic is superimposed on the power supply at an amplitude ratio of 3.2% or moreStream i_sThus, the effective value of the motor current is reliably reduced.

As described above, the control unit 40 sets the amplitude ratio to 9% or more under the rated condition (which may be either the cooling rated condition or the heating rated condition, the same applies hereinafter), and sets the amplitude ratio to 4% or more under the maximum condition (which may be either the cooling maximum condition or the heating maximum condition, the same applies hereinafter). The amplitude ratio can be adjusted by the lengths α 1 and α 2 of the non-conduction period and the magnitude of the harmonic parameter i 3. For example, the lengths α 1 and α 2 of the non-conduction period to be output by the harmonic parameter selection unit 50 and the magnitude of the harmonic parameter i3 may be determined in advance by experiments or simulations.

In the power converter 10, the amplitude ratio under the maximum condition is controlled to be smaller than the amplitude ratio under the rated condition in an arbitrary power supply half cycle. In other words, control unit 40 controls the switching operation so that the amplitude ratio decreases in accordance with the magnitude of power supply power Pin.

The air conditioner 1 is premised on satisfying a predetermined harmonic standard. The harmonic standard may be a harmonic standard (hereinafter referred to as IEC standard) in the International Electrotechnical Commission (IEC).

In this embodiment, the power supply current i is set_sThe ratio of the size of the harmonic contained in (1) to the standard value of the harmonic standard is referred to as a ratio upper limit value. For example, when the ratio upper limit value is made different between the rated condition and the maximum condition, the effect of reducing the effective value of the motor current is reduced under either the rated condition or the maximum condition. On the other hand, by matching the proportional upper limit value under the rated condition with the proportional upper limit value under the maximum condition and setting the amplitude ratio closer to the proportional upper limit value, the harmonic standard is satisfied under the rated condition and the maximum condition, and the effect of reducing the effective value of the motor current is increased.

Fig. 18 shows a relationship between the scale upper limit value and the amplitude ratio. The horizontal axis of fig. 18 represents the upper limit of the scale. The ordinate of fig. 18 represents the amplitude ratio under the maximum condition in terms of a ratio to the amplitude ratio under the rated condition. As shown in fig. 18, the amplitude ratio under the maximum condition is 50% or more of the amplitude ratio under the rated condition in the range where the upper limit of the ratio is 40% to 100%. In order to sufficiently reduce the effective value of the motor current under the maximum condition and the rated condition at the set upper limit of the ratio, the amplitude ratio under the maximum condition needs to be 50% or more of the amplitude ratio under the rated condition. The same applies to the "rated conditions" whether the cooling rated conditions or the heating rated conditions are used. Similarly, the cooling maximum condition may be adopted as the "maximum condition", and the heating maximum condition may be adopted as the "maximum condition".

As described above, in the present embodiment, the control unit 40 controls the switching operation so that the amplitude ratio under the maximum condition becomes 50% or more of the amplitude ratio under the rated condition. The amplitude ratio can be adjusted by the lengths α 1 and α 2 of the non-conduction period and the magnitude of the harmonic parameter i 3. For example, the lengths α 1 and α 2 of the non-conduction period to be output by the harmonic parameter selection unit 50 and the magnitude of the harmonic parameter i3 may be determined in advance by experiments or simulations. In the air conditioner 1, the effective value of the motor current can be reduced while satisfying the harmonic standard.

As described above, the present embodiment relates to an air conditioner including: the air conditioner 1 includes: a motor 30; a power conversion device 10 that supplies power to the motor 30; and a control unit 40 for controlling the power conversion device 10,

the power conversion apparatus 10 includes:

an ac/dc conversion circuit 11, the ac/dc conversion circuit 11 rectifying an ac voltage of a single-phase ac power supply 20;

a DC link unit 12 having a capacitor C, the DC link unit 12 generating a DC voltage v pulsating in accordance with the frequency of the AC voltage by using the output of the AC/DC conversion circuit 11 as an input_dc(ii) a And

a DC-AC conversion circuit 13, the DC-AC conversion circuit 13 having a plurality of switching elements Su, Sv, Sw, Sx, Sy, Sz,

the capacitance value of the capacitor C is set such that the dc voltage v is set to be the maximum value of the air conditioner 1_dcIs said direct voltage v_dcMore than twice as small as the minimum value of (c),

the dc/ac conversion circuit 13 converts the dc voltage v by switching the switching elements Su, Sv, Sw, Sx, Sy, Sz_dcConverted into an alternating voltage of a predetermined frequency and output to the motor 30,

the control unit 40 controls the switching operation so that the input current i to the power conversion device 10 is input_sHas a non-conduction period, and a non-conduction period,

the control unit 40 controls the switching operation so that the input current i is equal to the maximum condition of the air conditioner 1_sThe phase of the fifth harmonic of the fundamental wave included in (b) is in a range of 90 ° to 270 °, and an amplitude ratio, which is a value of (amplitude of the fifth harmonic)/(amplitude of the fundamental wave component), is smaller than the amplitude ratio under the rated condition of the air conditioner 1.

Effects of the present embodiment

As described above, in the present embodiment, the amplitude ratio is controlled in accordance with the power supply power Pin. With this configuration, in the present embodiment, suppression of the effective value of the motor current and suppression of the harmonic current included in the power supply current can be achieved in a balanced manner.

(other embodiments)

Instead of the table, the dq-axis current parameter selection unit 48 may use a function installed in a program. The values of the d-axis current parameter Pd of the first table Tb1 and the second table Tb2 may be changed according to the power supply phase θ in.

The current command calculation unit 42 may hold information that is a basis of the generation of the third waveform in the form of a function incorporated in the program or a table obtained in advance.

The embodiments and modifications have been described above, but it is understood that various changes and modifications can be made without departing from the spirit and scope of the claims. The above embodiments and modifications may be appropriately combined or substituted as long as the functions of the objects of the present disclosure are not impaired.

Industrial applicability-

As described above, the present disclosure is useful for an air conditioner.

-description of symbols-

1 air-conditioning apparatus

10 power conversion device

11 AC-DC conversion circuit

12 DC link part

13D/A converter circuit

20 AC power supply

30 electric motor

40 a control unit.