JP2009118568A - Apparatus and method for controlling three-phase motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reproduce a three-phase winding current by only a simple circuit without using a high-speed, high-performance AD converter or MPU, when the winding current is reproduced using a bus direct current passed through a shunt resistor of an inverter in a controller for PMSMs (Permanent-Magnet Synchronous Motors). <P>SOLUTION: A detection possible range winging current reproduction unit 34 uses positive or negative detection possible period signals U<SB>P</SB>to W<SB>N</SB>generated from PWM Data in the PWM signal generation unit 12 of MPU 1. It thereby samples and holds a bus direct current I<SB>s</SB>passed through the shunt resistor R<SB>s</SB>of the inverter 2. Then it uses the sampled and held current value to interpolate the winding current in a detection impossible period and generates winding currents i<SB>us</SB>to i<SB>ws</SB>in a detection possible range. An estimated winding current generation unit 35 uses the winding currents i<SB>us</SB>to i<SB>ws</SB>in the detection possible range to estimate winding currents in the detection impossible range and generates estimated winding currents ^iu to ^iw. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention reproduces a three-phase winding current using a single shunt resistance current detection method, and by the reproduced winding current, a permanent magnet synchronous motor, a three-phase induction motor, a three-phase stepping motor, a synchronous motor, The present invention relates to a control device and a control method for a three-phase motor that controls a three-phase motor (a motor having a three-phase winding) such as a reluctance motor or a three-phase linear motor.

FIG. 9 is a block diagram of a controller for a permanent magnet synchronous motor (hereinafter referred to as PMSM) using a conventionally proposed one-shunt resistance current detection method (see, for example, Non-Patent Document 1).
The PMSM U-phase, V-phase, and W-phase winding currents i _u , i _v , and i _w are supplied from an inverter 66. The total of six MOSFETs of the upper arm 3 and the lower arm 3 of the inverter 66 are controlled by the switching signals U _up , V _up , W _up and the switching signals U _down , V _down , W _down of the PWM Data, Turn off. The PWM data is generated by the triangular wave carrier comparison method in the PWM signal generation unit 62 of the MPU 61.
The sampling unit 63 of the MPU 61 is controlled by the timing signal TS based on the PWM signal to sample the DC bus current i _s flowing through the shunt resistor R _s of the inverter 66. The AC current calculation unit 64 of the MPU 61 performs AD conversion on the sample of the sampling unit 63, calculates the winding currents i _{u to} i _w according to the PWM signal of the PWM signal generation unit 62 using the digital signal of the sample, and generates To do. The control unit 65 of the MPU 61 generates voltage commands v _u , v _v and v _w using the winding currents i _{u to} i _w of the AC current calculation unit 64, and outputs the voltage commands v _u , v _v and v _w . This is supplied to the PWM signal generator 62.

Tetsuya Fukumoto, Yukie Watanabe, Hiroto Sone, Yoichi Hayashi: “A Method of AC Current Calculation by Detecting DC Current in a Three-Phase PWM Inverter”, IEICE Transactions D, 127, 2, 2007: pp. 181-188

Conventional single shunt resistor current detection method, when generating the coil current i _u through i _w, several times a carrier one cycle, extracts the DC bus current i _s, the DC bus current AD conversion, in a MPU The winding currents i _{u to} i _w must be calculated. For this reason, a high-speed, high-resolution AD converter is required, and an MPU capable of high-speed computation is required, which increases the costs of the AD converter and the MPU.
In view of the above-mentioned problems of the conventional single-shunt resistance current detection method, the present invention directly converts the DC bus current into AD and reproduces the three-phase winding current in the MPU as in the prior art. By reproducing a three-phase winding current using a simple circuit with an analog amount, a high-speed, high-resolution AD converter and an MPU capable of high-speed computation are not required when reproducing the three-phase winding current. An object of the present invention is to provide a control device and a control method for a phase motor.

In order to achieve the object of the present invention, the control device for a three-phase motor according to claim 1 includes an inverter that controls a switching element by a PWM signal and supplies current to a three-phase winding, and the inverter The winding current of each phase in the detectable period is detected based on the PWM signal from the DC bus current flowing in the shunt resistor connected to the bus of the current, and the winding current of each phase is detected using the detected winding current. In a three-phase motor control device that reproduces continuously and uses the reproduced winding current for control, each phase detected in the detectable period within the detectable range of the winding current detectable period and the undetectable period Detectable range winding current reproduction unit that reproduces the winding current of each phase in the detectable range by interpolating the winding current in the undetectable period using the winding current of the coil, winding of each phase in the detectable range Other current and its phase The winding currents in the undetectable range obtained from the winding currents in the two-phase detectable range are synthesized in time series to continuously reproduce the winding currents in the entire detectable range and undetectable range. An estimated winding current generator is provided.
The three-phase motor control device according to claim 2 is the three-phase motor control device according to claim 1, wherein the three-phase motor is a permanent magnet synchronous motor.
The three-phase motor control device according to claim 3 is the three-phase motor control device according to claim 1 or 2, wherein the detectable range winding current reproduction unit is a positive detection generated from a PWM signal. The estimated winding current generator comprises a plurality of sample and hold circuits that are controlled by the possible period signal and the negative detectable period signal and detect and hold the winding current value of the detectable period from the DC bus current. Select and detect the winding current of each phase in the detectable range when a detectable range signal is generated when a positive / negative detectable period signal consisting of a positive detectable period signal and a negative detectable period signal is detected It is characterized by comprising a switch circuit for selecting a winding current in an undetectable range obtained from a winding current in a detectable range of the other two phases of the phase when no possible range signal is detected.
A control device for a three-phase motor according to claim 4 is the control device for a three-phase motor according to claim 3, wherein a pulse signal corresponding to a PWM cycle is generated and detected when the positive / negative detectable period signal is detected. A detectable range signal generating unit that generates a possible range signal is provided, and the switch circuit is controlled by the detectable range signal generating unit.

6. The method for controlling a three-phase motor according to claim 5, wherein a PWM signal is generated from a DC bus current flowing in a shunt resistor connected to a bus of an inverter that controls a switching element by a PWM signal and supplies a three-phase winding current. The winding current of each phase during the detectable period is detected based on the detected winding current, and the winding current of each phase is reproduced using the detected winding current, and the reproduced winding current is used for control. In the phase motor control method, the winding current of the undetectable period is interpolated using the winding current of each phase detected in the detectable period of the detectable range in the detectable range consisting of the detectable period and the undetectable period. To reproduce the winding current of each phase in the detectable range, and the undetectable range obtained from the winding current of each phase in the detectable range and the other two-phase detectable current in that phase. Combine winding current of each phase in time series The winding current of the entire range of detectable range and undetectable range reproduced continuously Te, characterized by the use to control the reproduction windings currents.
A three-phase motor control method according to a sixth aspect is the three-phase motor control method according to the fifth aspect, wherein the three-phase motor is a permanent magnet synchronous motor.
A control method for a three-phase motor according to claim 7 is the control method for a three-phase motor according to claim 5 or 6, wherein the interpolation is capable of negative detection and a positive detectable period signal generated from a PWM signal. The sample and hold circuit is controlled by the period signal to detect and hold the winding current value of the detectable period from the DC bus current, and reproduce the winding current of each phase of the detectable range. The time-series synthesis of the winding current of each phase in the undetectable range obtained from the winding current of the phase and the other two phases of the detectable range of the phase is the negative detection period signal and the negative current signal. When a positive / negative detectable period signal consisting of a detectable period signal is detected, a pulse signal corresponding to a PWM cycle is generated to generate a detectable range signal, and each of the detectable ranges is detected when the detectable range signal is detected. Select and check the phase winding current When range signal is not detected and performing by selecting each of the winding phase current undetectable range calculated from the winding current of the detectable range of the other two phases of that phase.

  The present invention reproduces the winding current in the detectable range from the DC bus current, and continuously reproduces the winding current using the winding current in the detectable range, so that the detectable range of the winding current and The winding current of the entire range that cannot be detected is reproduced. In the process of reproduction, the winding current detected from the DC bus current can be continuously reproduced with a simple circuit using the analog amount without AD conversion. That is, according to the present invention, when reproducing the entire range of the winding current from the DC bus current, the winding current can be reproduced by converting the DC bus current into a digital quantity and processing it with a simple circuit without taking it into the MPU. A simple circuit that reproduces the winding current of each phase can be configured by a general-purpose operational amplifier, a logic circuit, or the like. Therefore, the present invention does not need to use a high-speed, high-resolution AD converter to reproduce the three-phase winding current from the DC bus current, and does not need to use an MPU capable of high-speed processing. The motor control device can be manufactured at low cost, and the control method of the three-phase motor becomes simple.

In the present invention, a control signal used in the process of reproducing the winding current in the detectable range from the DC bus current and in the process of reproducing the winding current in the entire range from the winding current in the detectable range is a switching signal (PWM signal). ), It can be generated easily.
The present invention can interpolate and reproduce the winding current during the non-detectable period using the sample current value detected during the period during which the winding current can be detected. For this interpolation, the DC bus current is sampled. Therefore, the interpolation circuit is simplified because it is only necessary to use a sample and hold circuit that holds the sample current value.
In the present invention, the winding current of each phase in the undetectable range can be estimated and reproduced using the winding current in the other two-phase detectable range of the phase, and the current in the detectable range is detected. Since it is only necessary to provide a circuit for selecting the current in the impossible range, the circuit for generating the estimated winding current is simplified.

  An embodiment of the present invention will be described with reference to FIGS. In addition, the same code | symbol is used for the part common to each figure.

First, the overall configuration of a control device for a permanent magnet synchronous motor (hereinafter referred to as PMSM), which is one of three-phase motors, will be described with reference to the block diagram of FIG. 1, and then each part will be described with reference to FIGS. Details will be described.
In FIG. 1, 1 is an MPU, 2 is an inverter, PMSM is a permanent magnet synchronous motor, and 3 is a three-phase winding current reproduction unit. The MPU 1 includes a PWM signal generation unit 12, a three-phase voltage command generation unit 13, and a triangular wave (carrier signal) generation unit 14. The inverter 2 includes an upper arm 211, a lower arm 212, a DC power source 22, a shunt resistor R _{s, and the} like, and is composed of a total of six MOSFETs (power devices) including three upper arms and three lower arms. The PMSM is composed of a U-phase, V-phase, and W-phase winding and a permanent magnet rotor (not shown) as shown in FIG. The winding current reproducing unit 3 includes a switching signal generating unit 30, a positive or negative detectable period signal generating unit 31, a positive / negative detectable period signal generating unit 32, a detectable range signal generating unit 33, and a detectable range winding current reproducing unit. 34, an estimated winding current generator 35 and the like.

The PWM signal generation unit 12 generates PWM Data by a triangular wave comparison method based on the three-phase voltage command (sine wave) of the voltage command generation unit 13 and the triangular wave of the triangular wave generation unit 14, and the inverter 2 and the switching signal generation unit 30. To supply. The PWM Data includes switching signals U _up , V _up , W _up for controlling the switching of the upper arm 211 of the inverter 2 and switching signals U _down , V _down , W _down for controlling the switching of the lower arm 212.
The inverter 2 is controlled by the switching signals U _{up to} W _up and U _{down to} W _down to supply three-phase winding currents i _u , i _v and i _w to the PMSM winding.

The switching signal generating unit 30 extracts the switching signal (upper arm PWM signal) U _{up to} W _up of the upper arm 211 from the PWM Data, and the positive or negative detectable period signal generating unit 31 outputs the switching signal U _up to Using W _up , positive detectable period signals U _P , V _P , W _P , negative detectable period signals U _N , V representing periods in which the winding current of each phase can be detected in a detectable range (described later). _N , W _N are generated, and the positive / negative detectable period signal generation unit 32 is based on the positive detectable period signals U _{P to} U _N and the negative detectable period signals U _{N to} W _N. Positive and negative detectable period signals U _PN , V _PN , W _PN are generated, and the detectable range signal generation unit 33 can detect and detect a pulse signal corresponding to a PWM cycle when a positive / negative detectable period signal is detected. range signal U _ON, V _ON, the W _ON raw To.

The detectable range winding current reproduction unit 34 reproduces the winding current in the detectable range from the DC bus current i _s flowing through the shunt resistor R _s , so that the positive detectable period signal U _{P to} W _P , the negative detectable period using the signal U _N to _W-N, and detects a winding current detectable period from the DC bus current i _s, it can be detected by interpolating the winding current undetectable period by using the detected winding current A range of winding currents i _us , i _vs , i _ws is generated.

The estimated winding current generator 35 generates (reproduces) a winding current in a non-detectable range (described later) using the winding currents i _{us to} i _ws in the detectable range, and The winding current and the winding current in the detectable range are synthesized in time series for each phase and estimated winding currents ^ i _u , ^ _iv , ^ i _w (hat i _u , hat i _v , hat i _w ) is generated. A switch circuit controlled by the detectable range signals U _{ON to} W _ON is used to generate the estimated winding currents i _u to i _w . In addition, in order to generate a winding current in an undetectable range, the total winding current uses a relationship of 0 (Kirchhoff's law).
For example, in the case of the U phase, when the detectable range signal U _ON is generated, ^ i _u = i _us , and when the detectable range signal U _ON is not generated, ^ i _u = − (i _vs + i _ws ) And i _{us and-} (i _vs + i _ws ) are synthesized in time series to generate an estimated winding current ^ _iu . Therefore, the detectable range and undetectable range of the winding current, that is, the winding current ｉ _u in the entire range, is ｉ _u = U _ON × i _{us -bar} U _ON × (i _vs + i _ws ). The same applies to the V phase and the W phase.

As described above, the detection range winding current reproduction unit 34 uses the positive detection detectable period signals U _{P to} W _P and the negative detection detection period signals U _{N to} W _N with respect to the detection range of the winding current. detecting a winding current detectable period from the current i _s, reproduce the winding current i _us through i _ws detectable range by interpolating the winding current undetectable period by using the detected winding current To do. On the other hand, the estimated winding current generator 35 reproduces the winding current in the undetectable range by using the winding currents i _{us to} i _ws in the detectable range for the winding current undetectable range, and A line current and a winding current in a detectable range are synthesized in time series to generate estimated winding currents i _u to i _w .
The reproduced estimated winding currents ^ i _u to ^ i _w are AD converted and taken into the MPU 1 and used for controlling the PMSM.
In FIG. 1, the switching signals U _{up to} W _up of the upper arm 211 of the inverter 2 are used to reproduce the winding current. However, the switching signals U _{down to} W _down of the lower arm 212 may be used. The MOSFETs on the upper and lower arms of the inverter 2 may be other switching elements.

Here, the detectable range, the undetectable range, the detectable period, the undetectable period, the positive detectable period signal, the negative detectable period signal, and the positive / negative detectable period signal of the winding current will be briefly described. Details will be described later.
The winding currents i _u , i _v , i _w flowing through the three-phase windings flow from the inverter to the motor (winding) direction (referred to as positive direction) and from the motor (winding) to the inverter direction (negative direction). Repeat the flow to). Also based on the switching signal (PWM signal) U _up ~W _up, when detecting a phase of the winding current from the DC bus current i _s, the positive direction of the winding current and the negative direction of the winding current, detected There is a range that can be detected and a range that cannot be detected. The former range is called a detectable range, and the latter range is called an undetectable range. Even within the detectable range, there are periods in which the winding current can be detected and periods in which it cannot be detected. The former period is called a detectable period, and the latter period is called an undetectable period. The positive detectable period signal, the negative detectable period signal, and the positive / negative detectable period signal are both signals indicating the detectable period, but the positive detectable period signal and the negative detectable period signal are either positive or negative. A winding current detectable period is represented, and the positive / negative detectable period signal represents a positive period and negative direction (both positive and negative directions) winding current detectable period.

Next, details of each part will be described with reference to FIGS.
Figure 2 illustrates the switching signal (PWM signal) U _up ~W _up and winding current i _u through i _w, a relationship of the DC bus current i _s.
In FIG. 2, A and D indicate the directions of currents flowing through the three-phase windings (the windings are omitted), and B and H are switching functions (logic functions) f (U _up , V _up , state of W _{Stay up-),} i.e. shows the state of MOSFET switching of the upper arm 211 of the inverter 2, c, f shows a relationship between winding current i _u through i _w and the DC bus current i _s. Further, the positive detectable period signals U _P , V _P , W _P are currents from the inverter to the motor direction (positive direction) when the DC bus current i _s (winding currents i _u , i _v , i _w ) is positive. period is flowing (or state), and when the DC bus current i _s is negative, indicates a period (or state) where a current flows from the motor to the inverter direction (negative direction), the negative current detectable period signal U _N, V _N, W _N, when the DC bus current i _s is positive, the period in which current flows from the motor to the inverter direction (negative direction) (or state), also the DC bus current i _s is negative The period (or state) during which current flows from the inverter in the motor direction (positive direction).

(1) to (6) in FIG. 2 show the case where the state variables of the switching function f (U _up , V _up , W _up ) are as follows. Note that state variable 1 represents an ON state, and state variable 0 represents an OFF state.
_{(1) f (U up,} V up, W up) = U P = 1 when the period i _u = i _s of (1,0,0), U _P = 0 in other cases
(2) Period of f (U _up , V _up , W _up ) = (0, 1, 1) U _n = 1 when i _u = −i _s , otherwise U _N = 0
_{(3) f (U up,} V up, W up) = period of _{(0,1,0) i v = V P} = 1 when i _s, V _P = 0 in other cases
_{(4) f (U up,} V up, W up) = period of _{(1,0,1) i v = V N} = 1 when the -i _s, V _N = 0 in other cases
_{(5) f (U up,} V up, W up) = W P = 1 when the period i _w = i _s of (0,0,1), W _P = 0 at other times
_{(6) f (U up,} V up, W up) = W N = 1 when the period i _w = -i _s of (1,1,0), W _N = 0 in other cases

Next, referring to FIG. 3, using the three-phase voltage command (sine wave) of the voltage command generation unit 13 of FIG. 1 and the triangular wave of the triangular wave generation unit 14, the switching signal generated by the PWM signal generation unit 12 of FIG. The arm PWM signals U _{up to} W _up will be described.
The switching signals U _{up to} W _up are generated by a triangular wave comparison method using the three-phase voltage commands v _u , v _v and v _{w of} FIG. Switching signal U _{Stay up-to W-Stay up-at} time TA in FIG. 3 (a), is as shown in FIG. 3 (b1), the switching signal U _{Stay up-to W-Stay up-at} time TB is as shown in FIG. 3 (b2).
3 (b1) and 3 (b2), (a) shows the relationship between the instantaneous values of the voltage commands v _{u to} v _w and a triangular wave, and (b) shows the output voltage (PWM output voltage) of the switching signal. , (c) the switching signal pattern (PWM patterns), shows the winding current can be detected and the DC bus current i _s. The switching signal patterns, switching signal U _{Stay up-to W-Stay up-inverter} of the upper arm of the ON controlled by (1) represents the OFF (0) state, the DC bus current i _s are those ON, OFF state Represents the winding current that can be detected at.

For Figure 3 (b1), the instantaneous value of the voltage command v _u to v _w are different with the three-phase, when the instantaneous value of the voltage command _v v, v _w are the same, the voltage command v _u (b2) The instantaneous value is different from the other two phases. The case of FIG. 3 _{(b1), (U up,} V up, W up) = period (1,0,0) is _{i s = i u, (U} up, V up, W up) = (1, 1, 0), i _s = −i _w , and during these periods, the winding currents i _u and i _w can be detected from the DC bus current i _s . On the other hand, during the period of (U _up , V _up , W _up ) = (0, 0, 0), (1, 1, 1), the winding current cannot be detected.

If Figure 3 _{(b2), (U up,} V up, W up) = period (0,1,1) is _{i s = -i u, (U} up, V up, W up) = (1, In the period of 0,0), i _s = i _u , and during these periods, the winding current i _u can be detected from the DC bus current i _s . On the other hand, the winding current cannot be detected during the period (U _up , V _up , W _up ) = (0, 0, 0). Therefore, when the winding currents i _{u to} i _w are detected from the DC bus current i _s based on the switching signals U _{up to} W _up , during the period of the triangular wave, a phase that can detect the winding current is not detected. There are possible phases and periods where detection is possible and periods where detection is impossible.
Winding current which can be detected during one period of the triangular wave as described above, only if i _u and i _w, if i _u of FIG. 3 (b2) of FIG. 3 (b1). That is, when the instantaneous values of the voltage commands v _u , v _v , v _w are different from the three phases as shown in FIG. 3 (b1), the two-phase winding current can be detected, and as shown in FIG. 3 (b2), When the instantaneous values of the two phases (v _v , v _w) of the voltage commands v _u , v _v , v _w are the same, a one-phase winding current can be detected.

Next, the detectable range and undetectable range of the winding current will be described.
When the detection period of the winding current i _u during one period of the triangular wave is even once, the winding current i _u is defined as detectable range. The winding currents i _v and i _w are defined similarly. For example, when the instantaneous values of the voltage commands v _u , v _v , and v _w are different from the three phases as shown in FIG. 3 (b1), the two phases of the U phase with the maximum instantaneous value and the minimum W phase at that time Winding currents i _u and i _w are defined as a detectable range. When only the instantaneous values of the two-phase voltage commands v _v and v _w are the same among the voltage commands v _u , v _v and v _w as shown in FIG. The current i _u is defined as a detectable range. Here, as shown in FIG. 3 (b2), the condition that only the one-phase winding current can be detected is only the moment when the two-phase voltage commands v _v and v _w are the same. It is not necessary to consider the only detectable range.

FIG. 4 shows the detectable range of the winding current based on the above definition.
4A shows the maximum and minimum ranges of the instantaneous values of the voltage commands v _u , v _v and v _w , and FIG. 4B shows the winding currents i _u , i _v and i _w . Indicates the detectable range.
In FIG. 4A, for example, the U-phase maximum indicates a range in which the U-phase instantaneous value of the voltage commands v _{u to} v _w is larger than the other two phases, and the U-phase minimum indicates the U-phase instantaneous value. A range smaller than the amplitude of the other two phases is shown. The same applies to the V phase and the W phase.
4A is the range in which the winding current i _u can be detected from the DC bus current i _s , and the detectable range is as shown in FIG. 4B. Become. The same applies to the V phase and the W phase. Between the U-phase maximum and U-phase minimum range in FIG. 4A, and while the winding current i _{u in} FIG. 4B is not in the detectable range (between the winding current i _u and the winding current i _u ). ) Is the undetectable range of the winding current i _u . The same applies to the V phase and the W phase. The winding current non-detectable range is a range in which the instantaneous value of the voltage command of each phase is located between the instantaneous values of the other two-phase voltage commands of that phase. For example, in the case of the U phase, the range in which the instantaneous value of the voltage command v _u is larger than the instantaneous value of the voltage command v _v and smaller than the instantaneous value of the voltage command v _{w and} the instantaneous value of the voltage command v _u is _v is greater range than the instantaneous value of the smaller the voltage command v _w than the instantaneous value of.

In the detectable range, the winding currents i _{u to} i _w can be detected in the case of FIG. 4B, but even in the detectable range, as described above, the winding current detectable period (FIG. 3 ( b1) (1, 0, 0, etc.) and a non-detectable period ((0, 0, 0), etc. in FIG. 3 (b1)). Therefore, the winding current in the non-detectable period is interpolated using the winding current detected in the detectable period, thereby continuously reproducing the winding current in the detectable range. Here, the winding current reproduced by interpolation is referred to as a detectable winding current.
The winding current in the detectable range is generated using a sample and hold circuit (hereinafter referred to as S & H) in the detectable range winding current reproduction unit 34 in FIG. Detectable range winding current reproduction unit 34 includes a positive current detectable period signal U _P to _W-P, and controls the S & H with negative detectable period signal U _N to _W-N, the sampling the DC bus current i _s A value is held, and a winding current in a detectable range is generated using the held current value (sample current value). The configuration of the detectable range winding current unit 34 will be described later.

Here, the positive detectable period signals U _{P to} W _P and the negative detectable period signals U _{N to} W _N generated by the positive or negative detectable period signal generation unit 31 of FIG. 1 will be described.
First, taking the U phase as an example, the positive detectable period signal _UP and the negative detectable period signal _UN will be described.
In the case of FIG. 2 (1), the switching function f (U _up , V _up , W _up ) = (1, 0, 0), and the DC bus current i _s and winding current i _u during this period are expressed as i _s = Since i _u , the winding current i _u can be detected from the DC bus current i _s . And this period, the DC bus current i _s is a period in which the winding current i _u flowing in the positive direction when positive, is a period in which flowing DC bus current i _s winding current i _u when is negative in the negative direction from the positive current detectable period signal U _P representing this period can be represented by the formula (1).
Likewise the case of FIG. 2 (2), the switching function _{f (U up, V up,} W up) = (0,1,1) , and this period is the winding current when the DC bus current i _s is positive i _u flowing in the negative direction (a i _s = -i _u) is a period, from the DC bus current i _s is i _u when the negative is time flowing in the positive direction, a negative current detectable period representing the period signal U _N can be expressed by equation (2).
The following Similarly V-phase winding current i _v positive detectable represents a period in which the flows in the positive or negative direction period signal V _P of the W-phase, W _P, and negative current detectable period signal V _N, W _N of the formula ( 3) to (6).

Next, a method for reproducing the winding current in the detectable range will be described based on the logics of the equations (1) to (6).
Relationship positive or represented by the formulas (1) to (6) and the negative current detectable period signal U _P to _W-N and the DC bus current i _s and the winding currents i _u, as described in FIG. 2, U _{When P} = 1, i _s = i _u , and when U _N = 1, i _s = −i _u . Similarly, V _P = 1 if _{i s = i v, V N} = 1 if _{i s = -i v, W P} = 1 if _{i s = i w, W N} = 1 if i _s = -i _w .
Thus, for a U-phase, sampling the DC bus current i _s by a positive current detectable period signal U _P, retains its current value, the holding current value (sampled current value) undetectable period by using the i _{Stay up-} interpolating winding current, sampling the DC bus current i _s the negative current detectable period signal U _N, it retains its current value, the winding current undetectable period by using the holding current value i _un By interpolating, it is possible to reproduce the U-phase winding current value i _us in the detectable range by combining the held current values. The same applies to the V phase and the W phase.

Therefore positive or sampling the DC bus current i _s by the negative current detectable period signal U _P to _W-N, and the current value held _{i up, i vp, i wp} , i un, i vn, and i _wn, detection range of the winding current i _us, i _vs, When i _ws, winding current i _us the detectable range, i _vs, i _ws can be obtained by equation (7) to (9).
i _us = i _up −i _un (7)
i _vs = i _vp −i _vn (8)
i _ws = i _wp −i _wn (9)

FIG. 5 shows the configuration of the detectable range winding current reproduction unit 34 that generates the winding currents i _{us to} i _ws in the detectable range represented by the equations (7) to (9) and the winding current in the detectable range. The waveforms of i _{us to} i _ws are shown.
In FIG. 5 (a), the DC bus current i _s is supplied to the S & H3421~3426 through the low-pass filter 341. S & H3421~3426 is controlled by positive or negative current detectable period signal U _P to _W-N, the current value samples and holds the DC-bus current i _s and i _up ~i _wn. The retained current values i _{up to} i _wn are combined for each phase to generate the winding currents i _{us to} i _ws in the detectable range.
For example, in the case of U-phase, S & H3421 is controlled to a positive detection period signal U _P generates a current i _{Stay up-holds} the current values sampled, S & H3422 is controlled by the negative current detectable period signal U _N The sampled current value is held and a current value i _un is generated. The held current values i _up and i _un are combined to generate a winding current i _us in a detectable range. Similarly, the winding currents i _vs and i _ws within the detectable range are also generated for the V phase and the W phase.
The detectable range of the winding currents i _{us to} i _ws reproduced by the winding current reproduction circuit 34 is as shown in FIG. 5B when there is no current delay due to the inductance component. That is, two phases of the winding currents i _{us to} i _{ws in the} detectable range are reproduced continuously.
Therefore, the winding current in the detectable range can be reproduced by the winding currents i _{us to} i _ws .

Next, a method for reproducing the winding current in a range where the winding current cannot be detected will be described.
The winding current in the non-detectable range uses the positive detectable period signals U _{P to} W _P and the negative detectable period signals U _{N to} W _N , i _u + _iv + i _w = 0 (the total winding current is 0) : Kirchhoff's law) relationship is used to estimate and reproduce using the winding currents i _{us to} i _ws in the detectable range. That is, the winding current in the undetectable range is reproduced using the winding currents i _{us to} i _ws reproduced in the detectable range.

In order to reproduce the winding current in the undetectable range, first, three-phase positive / negative detectable period signals U _{PN to} W _PN are generated. The positive / negative detectable period signals U _{PN to} W _PN represent the positive and negative periods (periods in both positive and negative directions) of the winding currents i _u , i _v , and i _w , and represent the detectable period. The positive / negative detectable period signals U _{PN to} W _PN can be expressed by the following logical expressions using the positive detectable period signals U _{P to} W _P and the negative detectable period signals U _{N to} W _N.
U _PN = _UP + _UN (10)
V _PN = V _P + V _N (11)
W _PN = W _P + W _N (12)

Next, when the positive / negative detectable period signal U _{PN to} W _PN is detected, when the positive / negative detectable period signal is detected, a pulse signal corresponding to the PWM cycle is generated and the detectable range signal U _{ON to} W _ON is generated. (Generating method will be described later).
The winding current in the undetectable range is further calculated using i _u + i _v + i _w = 0 (i _u) using the detectable range signals U _{ON to} W _ON and the winding currents i _{us to} i _ws of each phase in the detectable range. =-(I _v + i _w )). Estimated the winding current _{^ i u, ^ i v,} ^ i w can be expressed by the following equation.

ここで式（１３）の場合、ｉ_usは、巻線電流の検出可能範囲のＵ相の巻線電流であり、−（ｉ_vs＋ｉ_ws）は、巻線電流の検出不可能範囲のＵ相の巻線電流である。Ｖ相の式（１４）、Ｗ相の式（１５）についても同様である。したがって式（１３）〜（１５）の推定巻線電流＾ｉ_u，＾ｉ_v，＾ｉ_wは、巻線電流の検出可能範囲及び検出不可能範囲（即ち全範囲）の再現された巻線電流を表している。

Here, in the case of Expression (13), i _us is the winding current of the U phase in the detectable range of the winding current, and − (i _vs + i _ws ) is the U phase of the undetectable range of the winding current. Winding current. The same applies to the V-phase equation (14) and the W-phase equation (15). Thus the estimated winding current ^ i _u of formula (13) ~ (15), ^ i v, ^ i w is reproduced windings of the detectable range and undetectable range of the winding current (i.e. the entire range) It represents current.

FIG. 6 shows the configuration of the detectable range signal generator 33 and the estimated winding current generator 35.
In FIG. 6 (a1), the detectable range signal generating unit 33 includes detection signal generators 331 to 333 for three-phase positive / negative detectable period signals. FIG. 6A2 shows a specific example of the U-phase detectable range signal generator 331. FIG. The V phase and the W phase are configured similarly.
In the case of the U phase, when the positive / negative detectable period signal _UPN is detected, the detection signal generator 331 generates the pulse signal PP corresponding to the PWM cycle to generate the detectable range signal U _{ON. When ON} is not detected (not generated), an undetectable range signal bar U _ON is generated. The same applies to the V phase and the W phase.

In FIG. 6B, the estimated winding current generator 35 uses the winding currents i _us , i _vs , i _ws in the detectable range, and estimates the winding current ^ based on the equations (13) to (15). i _u , ^ i _v , ^ i _w are generated.
For example, in the case of the U phase, when the U phase detectable range signal U _ON of the detectable range signal is generated in the detection signal generator 331 of the positive / negative detectable period signal of FIGS. 6 (a1) and (a2), switch SWu is switched to U _oN side, (when the bar U _oN is generated) when the detectable range signal U _oN not generated, switched to bar U _oN side. That switch SWu is, when the detectable range signal U _ON is detected, switched to U _ON side, when the detectable range signal U _ON not detected is switched to bar U _ON side. On the U _ON side, the winding current i _us in the detectable range appears, and on the bar U _ON side, the winding current in the undetectable range obtained from the winding currents i _vs and i _{ws in} the detectable range. Appears. Thus when the switch SWu is switched to U _ON side, ^ i _u = i _us next, when switched to the bar U _{ON side, ^ i u = - (i} vs + i ws) , and the a i _us - (I _vs + i _ws ) is synthesized in time series to become the estimated winding current ^ i _u . That estimate winding current ^ i _u is a winding current i _us the detectable range of the U-phase when the detectable range signal U _ON is detected, when the detection range signal U _ON not detected -(I _vs + i _ws ) which is a winding current in the undetectable range obtained from the winding current in the detectable range of the V and W phases. Further, i _us is a winding current in which the detectable range of the winding current is reproduced, and − (i _vs + i _ws ) is a reproduced winding current in the undetectable range of the winding current. Estimated the winding current ^ i _v of the V-phase, the estimated winding current ^ i _w of the W-phase is the same.

As described above, the estimated winding current generator 35 shown in FIG. 6B reproduces and generates the winding current in the entire range of the winding current detectable range and the undetectable range.
The detectable range signal generator 33 and the detectable range signal generator 331 are not limited to the configurations shown in FIGS. 6 (a1) and (a2), and when the signal U _ON in the detectable range is detected, If, it switches the switch SWu to U _ON side, when the signal U _ON detectable range is not detected, as long as the structure for switching the switch SWu to bar U _ON side. The same applies to the V phase and the W phase.

This embodiment has the formula (7) to reproduce - the winding current i _us through i _ws detectable range of the DC bus current i _s (9), finally detectable by the formula (13) to (15) Using the winding currents i _{us to} i _ws in the range, the winding currents ^ i _u to ^ i _w in the detectable range and the undetectable range (entire range) are reproduced. And in the course of their reproduction, the DC bus current i _s with left analog value without AD conversion, and reproduces the estimated winding current ^ i _u ~ ^ i _w of analog quantity. That is, the present embodiment, when reproducing the DC bus current i _s from the estimated winding current ^ i _u ~ ^ i _w, analog quantity without converting the digital value does not need to take the DC bus current i _s the MPU It can be processed with a simple circuit. The winding current estimation circuit can be configured by a general-purpose operational amplifier, a logic circuit, or the like. Therefore, in this embodiment, it is not necessary to use a high-speed, high-resolution AD converter, and it is not necessary to use an MPU capable of high-speed processing, so that a PMSM control device can be manufactured at low cost.

In order to verify the estimated winding current obtained by this embodiment, the estimated winding currents ^ i _u , ^ _iv and the winding currents i _u , _iv was compared.
In FIG. 7, 51 is an MPU having a PWM signal generation unit for generating PWM Data, 52 is an inverter, 53 is a winding current reproduction unit of the present embodiment, 54 is a test motor (PMSM), and 55 is The encoder 56 is a load and inertia, 57 is a coupling, and 58 is a CPLD.
The specifications of the experimental apparatus are as follows.
The sample motor has 4 poles, 6 slots, torque constant: 0.44 N · m / A, winding resistance: 0.94Ω, d-axis inductance: 4.7 mH, and q-axis inductance: 4.7 mH. . The inverter has a PWM frequency of 10 kHz, a dead time of 1 μsec, a shunt resistance R _{s of} 1Ω, a supply voltage of 60 V, and a power device of MOSFET.

FIG. 8 shows waveforms of the detected winding currents i _u and i _v (thick lines) and the estimated winding currents i _u and ^ i _v (thin lines) obtained by the experimental apparatus of FIG. 8 (a) is when the rotational speed of the PMSM is 1000min ^-1, FIG. 8 (b), U-phase, the estimated winding detecting winding currents of the V phase when the rotational speed of the PMSM is 500 min ^-1 The line current waveform is shown. The waveforms of the detected winding current and the estimated winding current are substantially the same in both cases of FIG. 8 (a) and FIG. 8 (b).

  In the above embodiment, PMSM (Permanent Magnet Synchronous Motor) has been described. However, in addition to PMSM, there are three-phase motors such as a three-phase induction motor, a three-phase stepping motor, a synchronous motor, a reluctance motor, and a three-phase linear motor. Also good.

The structure of the control apparatus of PMSM of the Example of this invention is shown. The relationship between the switching signal (PWM signal) which concerns on the Example of this invention, a winding current, and DC bus current is shown. The relationship between the voltage command of each phase which concerns on the Example of this invention, the switching signal (PWM signal) produced | generated by a triangular wave (carrier signal), and winding current is shown. The range which can detect the winding current which concerns on the Example of this invention is shown. The structure of the detectable range winding current generation part which concerns on the Example of this invention, and the waveform of the current winding current of a detectable range are shown. The structure of the detectable range signal generation part which concerns on the Example of this invention, and the presumed winding current generation part is shown. 1 shows a configuration of an experimental apparatus for verifying an estimated winding current according to an embodiment of the present invention. The waveform of the winding current detected by the experimental apparatus of FIG. 7 and the estimated winding current is shown. 1 shows a configuration of a conventional PMSM control device.

Explanation of symbols

1 MPU
12 PWM signal generator (PWM Data generator)
13 Voltage command generation unit 14 Triangular wave generation unit 2 Inverter 211 Upper arm 212 Lower arm 22 DC power supply 3 Winding current reproduction unit 30 Switching signal (PWM signal) generation unit 31 Positive or negative detectable period Signal generation unit 32 Positive / negative detectable period Signal generation unit 33 Detectable range signal generation unit 34 Detectable range winding current reproduction unit 35 Estimated winding current generation unit PMSM Permanent magnet synchronous motor R _s shunt resistance PWM Data U _{up to} W _up and U _{down to} W _{down
U up ~W up, U down ~W} down upper and lower arms of the switching signal U _P to _W-N positive or negative current detectable period signal U _PN to _W-PN negative detectable period signal U _ON to _W-ON detectable range signal i _s DC Bus currents i _u , i _v , i _w U phase, V phase, W phase winding currents i _{up to} i _wn Sampling current values i _us , i _vs , i _ws Detectable winding currents ^ i _u , ^ i _v , ^ i _w Estimated winding current v _u , v _v , v _w Voltage command

Claims (7)

  Each inverter of the three-phase winding is controlled by the PWM signal to supply current to the three-phase winding, and each of the detectable periods can be detected from the DC bus current flowing in the shunt resistor connected to the bus of the inverter based on the PWM signal. In a control device for a three-phase motor that detects a winding current of a phase, continuously reproduces the winding current of each phase using the detected winding current, and uses the reproduced winding current for control. Each phase of the detectable range by interpolating the winding current of the non-detectable period using the winding current of each phase detected during the detectable period in the detectable range consisting of the detectable period and non-detectable period of the line current Detectable range to reproduce the winding current of the winding current reproduction part, the detection range of the non-detectable range obtained from the winding current of each phase of the detectable range and the other two-phase detectable range of the phase Winding current in time series Form and the detectable range and undetectable range of the control device of the three-phase motor, characterized in that it comprises the estimated winding current generator to reproduce continuously winding current full range.   2. The three-phase motor control device according to claim 1, wherein the three-phase motor is a permanent magnet synchronous motor.   3. The control device for a three-phase motor according to claim 1 or 2, wherein the detectable range winding current reproduction unit is controlled by a positive detectable period signal and a negative detectable period signal generated from a PWM signal, and is DC. It consists of a plurality of sample & hold circuits that detect and hold a winding current value in a detectable period from the bus current, and the estimated winding current generation unit is positive / negative consisting of the positive detectable period signal and the negative detectable period signal Select the winding current of each phase of the detectable range when the detectable range signal to be generated is detected when the detectable period signal is detected, and when the detectable range signal is not detected, A control device for a three-phase motor, comprising a switch circuit that selects a winding current in a non-detectable range obtained from a winding current in a two-phase detectable range.   4. The control device for a three-phase motor according to claim 3, further comprising a detectable range signal generating unit that generates a detectable range signal by generating a pulse signal corresponding to a PWM period when the positive / negative detectable period signal is detected. The control circuit of the three-phase motor, wherein the switch circuit is controlled by the detectable range signal generation unit.   The winding current of each phase in the detectable period based on the PWM signal from the DC bus current flowing in the shunt resistor connected to the bus of the inverter that controls the switching element by the PWM signal and supplies the three-phase winding current In the control method of a three-phase motor that uses the detected winding current to continuously reproduce the winding current of each phase and uses the reproduced winding current for control, the detectable period and the detection failure In the detectable range consisting of possible periods, the winding current of each phase in the detectable range is interpolated using the winding current of each phase detected in the detectable period of the detectable range. It reproduces and chronologically combines the winding current of each phase in the undetectable range obtained from the winding current of each phase in the detectable range and the winding current in the other two-phase detectable range of that phase. Of detectable range and undetectable range To reproduce the range of winding current continuously, three-phase motor control method, characterized by use in controlling the reproduction windings currents.   6. The three-phase motor control method according to claim 5, wherein the three-phase motor is a permanent magnet synchronous motor.   7. The method for controlling a three-phase motor according to claim 5, wherein the interpolation is performed by controlling a sample and hold circuit with a positive detectable period signal and a negative detectable period signal generated from a PWM signal to control a DC bus current. The winding current value of the detectable period is detected and held to reproduce the winding current of each phase of the detectable range, the winding current of each phase of the detectable range and the other two phases of the phase The time-series synthesis of the winding current of each phase in the undetectable range obtained from the winding current in the detectable range detects the positive / negative detectable period signal composed of the positive detectable period signal and the negative detectable period signal. Then, a pulse signal corresponding to the PWM cycle is generated to generate a detectable range signal, and when the detectable range signal is detected, the winding current of each phase of the detectable range is selected, and the detectable range signal is If not detected Three-phase motor control method, which comprises carrying out by selecting each of the winding phase current undetectable range calculated from the winding current of the detectable range of the other two phases of the phase.

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