JP6514164B2 - Rotation position device for synchronous motor, air conditioner and washing machine - Google Patents

Description

  Embodiments of the present invention relate to an apparatus for estimating the rotational position of a synchronous motor, an air conditioner including the apparatus, and a washing machine.

  Conventionally, as a method of estimating the rotational position of a synchronous motor, for example, a method of calculating an induced voltage proportional to the speed of the synchronous motor from an input voltage and current to the synchronous motor and estimating based on the induced voltage is widely used. There is. However, although this method can obtain sufficient accuracy in the region where the synchronous motor is operated at high speed, there is a problem that accurate estimation can not be performed in the region operated at extremely low speed where the induced voltage information decreases.

  There is also proposed a method of applying an alternating current signal for sensing that is not related to the drive frequency to the synchronous motor and estimating the rotational position from the relationship between voltage and current. However, when the frequency of the AC signal is about several hundred Hz to several kHz, which is lower than the carrier frequency, the current ripple frequency of the motor falls within the audible range of human beings, thereby deteriorating the driving noise of the motor. On the other hand, in Patent Document 1, the high frequency current having the same frequency as the carrier frequency is generated by controlling the pulse width of each phase PWM signal for each half cycle of the carrier cycle, and the rotational position is estimated while suppressing noise. Methods have been proposed.

  Further, in Patent Document 2, a three-phase PWM signal is generated using three types of triangular wave carriers whose phases are shifted by 120 degrees with respect to one cycle of the carrier, thereby being equivalent to Patent Document 1 equivalently. There has been proposed a method of generating a high frequency current having the same frequency as the carrier frequency and estimating the rotational position by differentiating the current.

Patent No. 3454212 Patent No. 4670045

  In the method of estimating the rotational position using the high frequency current of the high frequency component and the carrier frequency component included in the inverter output, the high frequency current flowing according to the high frequency voltage is a disturbance to the voltage of the fundamental wave component of the inverter output. Since the carrier frequency is sufficiently high with respect to the rotational speed of the synchronous motor, it does not become a disturbance for torque. Further, this method does not need to add a low pass filter to the current feedback value in rotational position estimation, and has an advantage that the response as a control system is improved.

  However, in this method, from the viewpoint of practical use, the magnitude of the high-frequency current corresponding to the carrier frequency is determined depending on the parameters of the synchronous motor, so the effect differs depending on the synchronous motor used and various systems Not universally applicable to Specifically, in an electric motor having a small saliency or a large inductance, there is a problem that the current ripple component of the carrier frequency is small and the SN ratio of rotational position estimation is lowered. In addition, when the pulse width of the PWM signal is controlled in each carrier half cycle, there is also a problem that noise can not be sufficiently suppressed under the condition where the carrier frequency is low.

  Further, in both Patent Documents 1 and 2, processing is performed by converting the detected current into a two-phase coordinate system instead of the three-phase coordinate system. In other words, although the estimation of the rotational position is based on vector control based on a two-phase coordinate system, vector control requires complicated arithmetic operations and expensive arithmetic units, so the application of configuring the motor drive system at low cost Is not suitable for

  Therefore, a rotational position estimation device for a synchronous motor capable of estimating a rotational position at low cost while suppressing driving noise, and an air conditioner and a washing machine provided with the device are provided.

The rotation position estimation device for a synchronous motor according to the embodiment includes a current detection unit that detects a phase current of the synchronous motor, and a PWM generation unit that generates a three-phase PWM signal pattern so as to follow the rotation position of the synchronous motor. A detection timing signal generation unit that generates a detection timing signal based on a carrier wave of the PWM signal; and a current change amount detection unit that obtains a change amount of the phase current detected by the current detection unit according to the detection timing signal And a rotational position estimation unit configured to estimate a rotational position of the synchronous motor by comparing magnitude relationships of the change amounts corresponding to three types of voltage vector periods .

  The PWM generation unit is configured such that the current change amount detection unit generates three types of voltage vectors according to the fixed six detection timing signals generated by the detection timing signal generation unit within one cycle of the carrier wave. A three-phase PWM signal pattern is generated so that the phase current change amount corresponding to the period can be detected.

A functional block diagram showing a configuration of a motor control device according to a first embodiment A diagram in which the on state of the switching elements constituting the inverter circuit is represented by a space vector Diagram showing the relationship between the amount of change in current in each phase and the rotational position Functional block diagram showing the configuration of the rotational position estimation unit Diagram showing PWM carrier and pulse signals of each phase and current detection timing It is a 2nd embodiment, and is a figure showing PWM carrier and pulse signal of each phase, and current detection timing. It is a 3rd embodiment and a figure showing a case where a motor control device is applied to a compressor motor of an air conditioner. It is a 4th embodiment and is a figure showing the case where a motor control device is applied to a drum motor and / or a compressor motor of a washing drier. Diagram showing the configuration of a heat pump used in a washing and drying machine

First Embodiment
The first embodiment will be described below with reference to FIGS. 1 to 5. FIG. 1 is a functional block diagram showing a configuration of a motor control device. The direct current power source 1 is a power source for driving a permanent magnet synchronous motor (hereinafter simply referred to as a motor) 2 provided with a permanent magnet in a rotor. The direct current power supply 1 may be one obtained by converting an alternating current power supply into a direct current. The inverter circuit 3 is configured by three-phase bridge connection of six switching elements, for example, N-channel MOSFETs 4U +, 4Y +, 4W +, 4U-, 4Y-, 4W-, and is generated by the PWM generation unit 5 described later A voltage for driving the motor 2 is generated based on six switching signals of three phases.

  Voltage detection unit 6 detects voltage VDC of DC power supply 1. The current detection unit 7 is connected between the negative power supply line of the inverter circuit 3 and the negative terminal of the DC power supply 1. The current detection unit 7 is generally composed of a current sensor and a signal processing circuit using a shunt resistor, a hole CT, and the like, and detects a direct current Idc flowing through the motor 2.

  The current change amount detection unit 8 detects the DC current Idc six times based on detection timing signals t1 to t6 input from the detection timing signal generation unit 9 described later, and changes the difference value of the detection value every two times Calculated as dIu_V1, dIv_V3, and dIw_V5. The rotational position calculation unit 10 calculates the rotational position detection value θc of the motor 2 from the variation amounts dIu_V1, dIv_V3, and dIw_V5. Three-phase voltage command value generation unit 11 generates three-phase voltage command values Vu, Vv, Vw from voltage amplitude command value Vamp, which is a command value, and voltage phase command value φv.

  Duty generation unit 12 calculates modulation commands Du, Dv, Dw of each phase by dividing three-phase voltage command values Vu, Vv, Vw by DC voltage VDC. The PWM generation unit 5 compares the three-phase modulation commands Du, Dv, Dw with the PWM carrier and the carrier to generate PWM signal pulses of each phase. Dead time is added to the pulse corresponding to one, and the switching signals U +, U-, V +, V-, W-, and W- output to the three-phase upper and lower N-channel MOSFETs 4 are generated.

In the above configuration, the rotational position detection device 13 is configured without the motor 2 and the inverter circuit 3 . The motor control device 14 is configured by adding the inverter circuit 3 to the rotational position detection device 13.

（１）式に示すように、各相のインダクタンスＬｕ，Ｌｖ，Ｌｗは回転位置θに応じて変化する。このインダクタンスの回転位置に対する依存性を利用することで、モータの速度がゼロ近傍となる条件下でも転位置を推定することができる。 Here, the principle of the rotational position detection method in the present embodiment will be described. Equation (1) shows the three-phase inductance of the synchronous motor having saliency.

As shown in the equation (1), the inductances Lu, Lv and Lw of each phase change according to the rotational position θ. By utilizing the dependency of the inductance on the rotational position, it is possible to estimate the displacement even under conditions where the motor speed is near zero.

  FIG. 2 illustrates the on state of the switching elements that constitute the inverter circuit by a method called a space vector. For example, (1, 0, 0) indicates that the U-phase upper switching element is on and the V-phase and W-phase upper switching elements are off, and the voltage vector has eight patterns V0 to V7. .

但し、Ｖdcは直流電圧，Ｅｕ，Ｅｖ，Ｅｗは各相の誘起電圧，Ｒは巻線抵抗，Ｉｕ＿Ｖ１，Ｉｖ＿Ｖ１，Ｉｗ＿Ｖ１は、電圧ベクトルＶ１を印加した際の３相電流値である。ここでモータ回転数が極低速であり，巻線抵抗による電圧降下と誘起電圧が直流電圧Ｖｄｃに比べ非常に小さい場合、（２）式中の各相の電流微分値は（３）式を用いて（４）式に近似できる。

ここで、インダクタンス値Ｌ０，Ｌ１と直流電圧Ｖdcとを（５）式のようにＡと置くと、（４）式は（６）式に変形できる。

同様に、電圧ベクトルＶ３印加中のＶ相電流微分値ｄＩｖ＿Ｖ３／ｄｔ，電圧ベクトルＶ５印加中のＷ相電流微分値ｄＩｗ＿Ｖ５／ｄｔは（７）式で示される。電圧ベクトルＶ１，Ｖ３，Ｖ５印加中のＵ，Ｖ，Ｗ相の電流微分値に微分時間ｄｔを乗じて電流変化量とし、まとめたものが（８）式である。

Here, the inter-phase voltage equation of the second motor applying the voltage vector V1 (1, 0, 0) is shown in equation (2). From the top, UV line voltage, VW line voltage, and WU line voltage are shown.

Where Vdc is a DC voltage, Eu, Ev and Ew are induced voltages of respective phases, R is a winding resistance, and Iu_V1, Iv_V1 and Iw_V1 are three-phase current values when a voltage vector V1 is applied. Here, when the motor rotation speed is extremely low and the voltage drop due to the winding resistance and the induced voltage are very small compared to the DC voltage Vdc, the current differential value of each phase in the equation (2) uses the equation (3) (4) can be approximated.

Here, when the inductance values L0, L1 and the DC voltage Vdc are set to A as shown in the equation (5), the equation (4) can be transformed into the equation (6).

Similarly, the V-phase current differential value dIv_V3 / dt during application of the voltage vector V3 and the W-phase current differential value dIw_V5 / dt during application of the voltage vector V5 are represented by Expression (7). The current differential values of the U, V, and W phases during application of the voltage vectors V1, V3, and V5 are multiplied by the differential time dt to obtain a current change amount.

それぞれの交差位置がそれぞれ２種類の回転位置θを表すのは、（８）式の電流変化量が２θで変化するからである。 These three current change amounts have a DC offset amount 2 dt / A as shown in FIG. 3, and an alternating current signal having an amplitude L1 dt / (AL0) and a phase difference of 2 d / 3 according to the rotational position 2θ. It is. These are AC signals, but the offset amount 2 dt / A and the amplitude L 1 dt / (AL 0) include motor parameters. Therefore, in order to perform a simple rotational position calculation without using parameters, a zero cross signal of the difference value between the three signals is generated, and an estimated rotational position θc is determined based thereon. The rotational position at which the three-phase current change amounts shown in equation (8) cross each other is as shown in equation (9).

The respective intersection positions respectively represent two types of rotational positions θ because the amount of change in current in equation (8) changes with 2θ.

ここで、回転位置の分解能を「１２」とすれば、上記セクタ内における回転位置は、各相電流変化量の交差角度を平均した角度として（）内のように表すことができる。 Moreover, based on these intersection positions, it can be divided into six sectors according to the magnitude relationship of each phase.

Here, when the resolution of the rotational position is “12”, the rotational position in the sector can be expressed as in () as an angle obtained by averaging the crossing angles of the phase current change amounts.

また、別の実現方法として、（９）式で示した各相電流変化量の交差角度を用いて、電流変化量が交差した場合に回転位置を交差角度に更新する方法でも良い。 Next, an algorithm for determining which of two types of rotational positions to select for each sector will be described. When the motor rotates, the sector changes from 1 to 6 during one electrical angle cycle, and then changes from 1 to 6 again. Therefore, the first sectors 1 to 6 are considered as the first cycle of the sector, and the subsequent second cycle is considered as another sector. That is, as shown below, the rotational position is assigned to the number of sectors as “12”. This can be easily realized by using a counter that counts up after the sector changes from 1 to 6.

Further, as another realization method, a method may be employed in which the rotational position is updated to the intersection angle when the amount of change in current intersects, using the intersection angle of the amount of change in phase current shown in equation (9).

When using these methods, it is necessary to determine which position is correct from the amount of change in current of each phase before the motor rotates, that is, at the initial rotation position, before the counter starts counting. is there. For example, when the magnitude relation of the detected current variation is dIv_V3>dIu_V1> dIw_V5, the corresponding sector is 1 or 7, and the rotational position is 75 ° or -105 °.

In order to determine either of the above in the stopped state before the motor drive, an identification algorithm of the initial position is required. This determination is performed by a method using the characteristic of magnetic saturation which is a conventional known technique. About this well-known technique, there exist methods, such as the following literature, for example.
Journal of the Institute of Electrical Engineers of Japan, Journal of the Institute of Electrical Engineers of Japan, Vol. 125 (2005), No. 3 "Initial Rotation Position Estimation Method of Surface Magnet Synchronous Motor Using Pulse Voltage", Osamu Yamamoto, Yutaka Arataka The rotational position of the synchronous motor can be estimated from the amount of current change.

  FIG. 4 shows the configuration of the rotational position calculation unit 10. The comparator 21 u compares the input current change amount dIu_V1 with dIv_V3. The comparator 21v compares the input current change amount dIv_V3 with dIw_V5. The comparator 21 w compares the input current change amount dIw_V5 with dIu_V1. The output signals of the comparators 21 u to 21 w are input to the 2θc calculator 22. The 2θc calculating unit 22 calculates the rotational position 2θc based on six sectors from the combination of binary levels of the signals input by the comparator 21, and outputs the calculated rotational position 2θc to the counter calculating unit 23. The counter operation unit 23 is a counter that counts up after the number of sectors in the sector changes from 1 to 6 as described above, and outputs the rotational position θc according to the “12” sector.

Next, a method of detecting the amount of change in current during application of three types of voltage vectors shown in equation (8) will be described. It is necessary to detect the U-phase current during voltage vector V1, the V-phase current during V3, and the W-phase current during V5 application, respectively. Here, in the present embodiment, as shown in FIG. 5, three types of carriers having different waveforms are used as carriers for generating the PWM signal of each phase. For example, U phase is triangular wave carrier, V phase is reverse sawtooth wave carrier, and W phase is sawtooth wave carrier. When a PWM signal is generated using a carrier such as these, with reference to the U-phase triangular wave carrier,
U-phase PWM pulse: generated to both sides with respect to the valley of the triangular wave V-phase PWM pulse: generated to the left with reference to the mountain of the triangular wave W-phase PWM pulse: generated to the right with reference to the mountain of the triangular wave. Then, six detection timing signals t1 to t6 of current are given as shown in FIG.
The signals t1 and t2 for detecting the U-phase current change amount dIu_V1 from the direct current Idc are shifted by ΔT / 2 before and after the valley of the triangular wave. The DC current Idc to the V-phase current change amount dIv_V3 The signals t3 and t4 for detecting the current are ΔT before the peak of the triangular wave, and the times t and t6 for detecting the current change amount dIw_V5 of the W phase from the peak current and time Ic of the triangular wave The above is used as a reference at the time of ΔT later than the time of the mountain and the peak of the triangular wave.

  In addition, since the influence of noise on the current detection value may be large immediately after the pulse is generated, the detection timing may be shifted from the above reference value by about several microseconds. The detection timings of these t1 to t6 are six timings which are always constant, that is, fixed, regardless of the PWM signal input to the inverter circuit.

In order for the current values detected at these fixed timings to be U-phase current during vector V1 application, V-phase current during vector V3 application, and W-phase current during vector V5 application, the pulse width of each phase is used. It is necessary to set certain limitations as follows.
<DIu_V1 detectable condition>
U phase duty Du> ΔT
· V phase duty Dv <50%-ΔT / 2
· W phase duty Dw <50%-ΔT / 2
<DIv_V3 detectable condition>
・ U-phase duty Du <100% -2ΔT
· V phase duty Dv> ΔT
· W phase duty Dw <100%-ΔT
<Detectable Condition of dIw_V5>
・ U-phase duty Du <100% -2ΔT
· V phase duty Dv <100%-ΔT
· W phase duty Dw> ΔT
For this reason, when the rotational position is estimated as in the present embodiment, the modulation factor that can be output by the inverter circuit 3 is limited, but the modulation factor is generally low when the motor is stopped or at low speed.

  As described above, according to the present embodiment, the detection timing signal generation unit 9 generates the detection timing signals t1 to t6 based on the carrier wave of the PWM signal, and the current change amount detection unit 8 detects the detection timing signals t1 to t6. The amount of change of the phase current detected by the current detection unit 7 is determined according to The rotational position calculation unit 10 estimates the rotational position of the motor 2 based on the amount of change of the phase current.

  Then, in one cycle of the PWM carrier, the PWM generation unit 5 generates three types of voltage vector periods V1, V3, V5 according to the fixed six detection timing signals t1 to t6. The three-phase PWM signal pattern is generated so as to detect the phase current change amounts dIu_V1, dIv_V3, and dIw_V5 corresponding to the above.

  Specifically, the PWM generation unit 5 increases or decreases the duty Du in both directions of the delay side and the lead side with reference to an arbitrary phase of the PWM carrier cycle among the three phase PWM signals, and the V phase The duty Dv is increased or decreased in one direction on the delay side or the advance side with respect to the arbitrary phase, and the duty Dw is increased or decreased in the opposite direction to the direction with respect to the arbitrary phase. As a result, sensorless drive in the stop or low speed region of the motor 2 can be performed using an inexpensive computing element by a simple algorithm based only on the magnitude relationship of the detected current change amount without using an computing element having an expensive computing capability. It becomes possible.

  Further, since the PWM generation unit 5 sets the reference for generating the PWM pulse of each phase based on the phase at which the carrier amplitude is maximum or minimum, setting of the reference is simplified. Furthermore, the PWM generation unit 5 is a sawtooth wave whose phase shows maximum amplitude to the phase whose amplitude shows maximum or minimum at the phase where the amplitude of the triangular wave shows maximum or minimum for the V phase. Sawtooth waves that are in reverse phase to the sawtooth waves are used as carriers respectively. At that time, the reference of each phase is set based on the phase in which the maximum value or the minimum value of each carrier amplitude is all coincident. Thereby, the extension direction of the PWM pulse of each phase can be easily set.

Second Embodiment
Hereinafter, the same parts as those of the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted, and different parts will be described. In the second embodiment, PWM carriers to be used for each phase are set as shown in FIG. The carrier waveform used for each phase is the same, but in the second embodiment, the valleys of the U-phase triangle wave and the zero points of the V and W-phase sawtooth waves are matched.

Further, in the second embodiment, the pattern of the voltage vector is also different as described below with respect to the amount of change in current required to estimate the rotational position.
・ W-phase current change when voltage vector V2 is applied: dIw_V2
· U-phase current change amount when voltage vector V4 is applied: dIu_V4
・ V phase current change when voltage vector V6 is applied: dIv_V6
It becomes.
According to the second embodiment as described above, the same effect as that of the first embodiment can be obtained.

Third Embodiment
FIG. 7 shows a third embodiment, and shows a case where the motor control device of the first or second embodiment is applied to a compressor motor of an air conditioner. The compressor 32 constituting the heat pump system 31 is configured by housing the compression unit 33 and the motor 34 in the same iron airtight container 35, and the rotor shaft of the motor 34 is connected to the compression unit 33. The compressor 32, the four-way valve 36, the indoor heat exchanger 37, the pressure reducing device 38, and the outdoor heat exchanger 39 are connected to form a closed loop by a pipe serving as a heat transfer medium channel. The compressor 32 is, for example, a rotary compressor, and the motor 34 is, for example, a three-phase IPM (Interior Permanent Magnet) motor. The motor 34 is a brushless DC motor. The air conditioner 30 is configured to have the above-described heat pump system 31.

  At the time of heating, the four-way valve 36 is in the state shown by the solid line, and the high-temperature refrigerant compressed by the compression unit 33 of the compressor 32 is supplied from the four-way valve 36 to the indoor heat exchanger 37 and is condensed. The pressure is reduced at 38 and becomes low temperature and flows to the outdoor heat exchanger 39 where it evaporates and returns to the compressor 32. On the other hand, at the time of cooling, the four-way valve 36 is switched to the state shown by the broken line. For this reason, the high temperature refrigerant compressed by the compression unit 33 of the compressor 32 is supplied from the four-way valve 6 to the outdoor heat exchanger 39 to be condensed, and then decompressed by the decompression device 8 to become a low temperature to be indoors. It flows to the heat exchanger 37 where it evaporates back to the compressor 32. The fans 40 and 41 blow air to the indoor and outdoor heat exchangers 37 and 39, respectively, and the air flow efficiently exchanges heat between the heat exchangers 37 and 39, indoor air, and outdoor air. It is configured to be well done. Then, drive control of the motor 34 is performed by the motor control device of the first to third embodiments.

  According to the third embodiment configured as described above, the motor 34 of the compressor 32 constituting the heat pump system 31 of the air conditioner 30 is drive-controlled by the motor control device of the embodiment so that the air conditioner can be operated. 30 operating efficiency can be improved.

Fourth Embodiment
The fourth embodiment shown in FIGS. 8 and 9 shows the case where the motor control device is applied to a drum motor and / or a compressor motor of a washing and drying machine. FIG. 8 is a longitudinal side view schematically showing an internal configuration of the drum-type washing and drying machine 51. As shown in FIG. The outer case 52 forming the outer shell of the drum-type washing and drying machine 51 has a laundry entrance 53 opened in a circular shape on the front face, and the laundry entrance 53 is opened and closed by a door 54. Inside the outer case 52, a bottomed cylindrical water tank 55 whose back is closed is disposed, and a stator of the motor 50 is fixed to the back center of the water tank 45 by screwing. The rotating shaft 56 of the motor 50 is fixed to the shaft mounting portion of the rotor of the motor 50 at the rear end, the right end in FIG. 8, and the front end, the left end in FIG. ing.

  At the front end of the rotating shaft 56, a bottomed cylindrical drum 57 whose rear surface is closed is fixed coaxially to the water tank 55. The drum 57 is driven by a motor 50 to provide a rotor and a rotor. It rotates integrally with the rotating shaft 56. The drum 57 is provided with a plurality of flow holes 58 through which air and water can flow, and a plurality of baffles 59 for scraping and loosening the laundry in the drum 57. A water supply valve 60 is connected to the water tank 55, and when the water supply valve 60 is opened, water is supplied into the water tank 55. Further, a drainage hose 62 having a drainage valve 61 is connected to the water tank 55, and when the drainage valve 61 is opened, the water in the water tank 55 is drained.

  Below the water tank 55, a ventilating duct 63 extending in the front-rear direction is provided. The front end of the ventilation duct 63 is connected to the water tank 55 through the front duct 64, and the rear end is connected to the water tank 55 through the rear duct 65. A ventilation fan 66 is provided at the rear end portion of the ventilation duct 63, and the air inside the water tank 55 is indicated by an arrow by the ventilation action of the ventilation fan 66, from the front duct 64 to the ventilation duct 63. , And returned to the water tank 55 through the rear duct 65.

  An evaporator 67 is disposed on the front end side of the inside of the ventilation duct 63, and a condenser 68 is disposed on the rear end side. The evaporator 67 and the condenser 68 constitute a heat pump 71 together with the compressor 69 and the throttle valve 70 as shown in FIG. 9. The air flowing in the ventilation duct 63 is dehumidified by the evaporator 67 and the condenser 68 is dehumidified. And is circulated in the water tank 55. The throttle valve 70 is an expansion valve, and has an opening adjustment function.

  An operation panel 72 is provided on the front of the outer case 52 above the door 54, and the operation panel 72 is provided with a plurality of operation switches (not shown) for setting an operation course and the like. The operation panel 72 is connected to a control circuit unit (not shown) that mainly includes a microcomputer and controls the overall operation of the drum-type washing and drying machine 51. The control circuit unit is connected via the operation panel 72. Various operation courses are executed while controlling the driving of the motor 50, the water supply valve 60, the drain valve 61, the compressor 69, the throttle valve 70 and the like according to the set contents. Then, the motor control device of the first or second embodiment drives and controls the compressor motor that constitutes the motor 50 and / or the compressor 69.

  According to the fourth embodiment configured as described above, the motor control device according to the embodiment drives the motor 50 for rotating the drum in the washing / drying machine 51 and / or the compressor 69 constituting the heat pump system 71. By controlling, the operating efficiency of the washing and drying machine 51 can be improved.

(Other embodiments)
In order to generate a three-phase PWM signal as in each embodiment, the phase shift function or the like may be used without being limited to the use of three types of carriers, or the duty setting timing of one type of carrier may be used. Alternatively, methods such as changing the comparison polarity of pulse generation may be used.
The timing at which the current change detection unit 8 detects the three-phase current in the carrier cycle does not have to be based on the phase at which the level of the carrier exhibits the minimum or maximum, and a range in which the three-phase current can be detected It may be set based on an arbitrary phase of the carrier.

Further, the timing for detecting the current does not have to coincide with the period of the PWM carrier, and for example, the detection may be performed with a period twice or four times the carrier period. Therefore, the current detection timing signal input to the current change amount detection unit 8 does not have to be the signal itself obtained from the carrier, but may be a signal generated by a separate timer.
The current detection unit may be a shunt resistor or a CT.
The switching element may be a MOSFET, an IGBT, a power transistor, or a wide gap semiconductor such as SiC or GaN.

  While certain embodiments of the present invention have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and the gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

  In the drawing, 1 is a DC power supply, 2 is a permanent magnet synchronous motor, 3 is an inverter circuit, 4 is an N channel MOSFET, 5 is a PWM generation unit, 7 is a current detection unit, 8 is a current change detection unit, 9 is detection timing Reference numeral 10 denotes a rotational position calculation unit.

Claims (6)

A current detection unit that detects a phase current of the synchronous motor;
A PWM generation unit that generates a three-phase PWM signal pattern so as to follow the rotational position of the synchronous motor;
A detection timing signal generation unit that generates a detection timing signal based on the carrier wave of the PWM signal;
A current change amount detection unit for obtaining a change amount of the phase current detected by the current detection unit according to the detection timing signal;
A rotational position estimation unit configured to estimate a rotational position of the synchronous motor by comparing magnitude relationships of the change amounts corresponding to three types of voltage vector periods ;
The PWM generation unit is configured such that the current change amount detection unit detects three types of voltage vector periods according to the fixed six detection timing signals generated by the detection timing signal generation unit within one cycle of the carrier wave. A synchronous motor rotation position estimation device that generates a three-phase PWM signal pattern so that a corresponding phase current change amount can be detected. The PWM generation unit increases or decreases the duty in one of the delay side and the lead side with respect to an arbitrary phase of the carrier wave period with respect to one of three phases of PWM signals.
For one other phase, the duty is increased or decreased in one direction on the delay side or the lead side with reference to an arbitrary phase of the carrier cycle,
The rotational position estimation device for a synchronous motor according to claim 1, wherein the duty is increased or decreased in the opposite direction to the direction with reference to an arbitrary phase of the carrier wave for the remaining one phase.   The rotation position estimation device for a synchronous motor according to claim 2, wherein the PWM generation unit sets the reference of each phase based on a phase at which the amplitude of the carrier wave is maximum or minimum. The PWM generation unit uses a triangular wave as a carrier for one of the three-phase PWM signals,
For the other one phase, a sawtooth wave whose phase coincides with the maximum amplitude is used as a carrier wave as a phase whose amplitude indicates the maximum or minimum amplitude of the triangular wave,
For the remaining one phase, a sawtooth wave that is antiphase to the sawtooth wave is used as a carrier,
The rotational position estimation device for a synchronous motor according to claim 3, wherein the reference of each phase is set based on a phase in which the maximum value or the minimum value of each carrier wave amplitude is the same. Synchronous motor,
An inverter circuit that converts a direct current into a three-phase alternating current to drive the synchronous motor by on-off controlling a plurality of switching elements connected in a three-phase bridge according to a predetermined PWM signal pattern;
An air conditioner comprising the rotational position estimation device according to any one of claims 1 to 4 and performing an air conditioning operation by a rotational driving force generated by the synchronous motor. Synchronous motor,
An inverter circuit that converts a direct current into a three-phase alternating current to drive the synchronous motor by on-off controlling a plurality of switching elements connected in a three-phase bridge according to a predetermined PWM signal pattern;
A washing machine comprising the rotational position estimation device according to any one of claims 1 to 4, and performing a washing operation by a rotational driving force generated by the synchronous motor.

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