JP7734848B2 - Control device and drive control method - Google Patents

Description

This disclosure relates to a control device and a drive control method for controlling the drive of a rotating machine.

To drive a rotating machine, rotor position information is required. Rotor position can be detected using a position sensor, but using a position sensor leads to problems such as an increase in system size, higher costs, and reduced environmental resistance.

In contrast, Patent Document 1 discloses a method for estimating rotor position without using a position sensor. The method disclosed in Patent Document 1 estimates rotor position by utilizing the fact that the amount of change in rotating machine current during application of an effective voltage vector changes at an angle twice that of the rotor position.

Japanese Patent Application Laid-Open No. 2018-153027

However, the above-mentioned conventional technology poses a problem in that position estimation errors can increase in the occurrence pattern of effective voltage vectors in which the differential information of the rotating machine current is a fragmented signal. For example, when current vector control is performed using a three-phase common triangular wave carrier PWM (Pulse Width Modulation), there is a correlation between the type of effective voltage vector that appears due to current vector control and the rotor position, and when the rotating machine is driven at low speed, a specific type of effective voltage vector appears for a long period of time. Under such conditions, when the change in rotating machine current relative to the effective voltage vector is obtained, the change in rotating machine current becomes a fragmented signal.

The present disclosure has been made in consideration of the above, and aims to provide a control device that can estimate rotor position with high accuracy even under conditions where the amount of change in rotating machine current relative to the effective voltage vector is fragmented.

In order to solve the above-mentioned problems and achieve the object, a control device disclosed herein is a control device that performs drive control of a multi-phase rotating machine having salient poles , and includes a current detection unit that detects a rotating machine current flowing through the rotating machine, a drive voltage command calculation unit that generates a drive voltage command for driving the rotating machine based on the rotating machine current and an estimated value of a rotor position of the rotating machine, a voltage applicator that applies a voltage to the rotating machine based on the generated drive voltage command, and a position estimator that estimates the rotor position based on the rotating machine current, wherein the position estimator determines the type of voltage vector output by the voltage applicator based on a gate signal of the voltage applicator, calculates an amount of change in the rotating machine current for each determined type of voltage vector, generates an AC signal that has zero DC component and changes at an angle twice the rotor position based on the amount of change in the rotating machine current that is the calculation result, and estimates the rotor position based on the AC signal.

The present disclosure has the advantage of being able to obtain a control device that can estimate rotor position with high accuracy even under conditions where the change in rotating machine current relative to the effective voltage vector is fragmented.

FIG. 1 is a diagram showing a configuration of a control device for a rotating machine according to a first embodiment; FIG. 2 is a diagram showing an example of a circuit configuration of the voltage applicator shown in FIG. 1; FIG. 2 is a diagram showing an example of the correspondence between the switching state of each phase of the voltage applicator shown in FIG. 1 and the definition of a voltage vector. FIG. 4 shows the eight switching states and voltage vectors shown in FIG. 3. FIG. 2 is a diagram for explaining signal processing in the position estimator shown in FIG. 1; FIG. 6 is a diagram showing a detailed configuration of a current differential information calculation unit shown in FIG. 5 . FIG. 1 is a diagram showing DC and AC components included in current differential information; FIG. 6 is a diagram showing an output of the current differential information calculation unit shown in FIG. 5 . A diagram to explain the classification performed by the classifier An explanatory diagram of the operation of the classifier shown in FIG. FIG. 6 is a block diagram showing the configuration of the phase synchronization calculation unit shown in FIG. FIG. 6 shows the output of each part of the position estimator shown in FIG. 5 . FIG. 1 is a diagram illustrating a first example of a hardware configuration for realizing the functions of a control device according to the first and second embodiments. FIG. 10 is a diagram illustrating a second example of a hardware configuration for realizing the functions of the control device according to the first and second embodiments.

Below, the control device and drive control method relating to the embodiments of the present disclosure are described in detail with reference to the drawings.

Embodiment 1.
FIG. 1 is a diagram showing the configuration of a rotating machine control device according to a first embodiment. Hereinafter, the "rotating machine control device" may be simply referred to as the "control device." The control device 100 shown in FIG. 1 includes a rotating machine 1, a current detector 2, a voltage applicator 3, a position estimator 4, and a controller 5. The controller 5 includes a current controller 6, a rotating coordinate inverse converter 7, a two-phase to three-phase converter 8, a three-phase to two-phase converter 9, and a rotating coordinate converter 10.

The rotating machine 1 is a three-phase synchronous reluctance motor (SynRM) that generates torque using rotor saliency. A voltage applicator 3 is connected to the rotating machine 1, and a current detector 2 is installed between the rotating machine 1 and the voltage applicator 3.

The current detector 2 detects the AC current supplied from the voltage applicator 3 to the rotating machine 1 and outputs the AC current as rotating machine currents _iu , _iv , and _iw . The rotating machine currents _iu , _iv , and _iw are supplied to the rotating machine 1 and are also output to the position estimator 4 and the controller 5.

The voltage applicator 3 supplies AC power to the rotating machine 1 in accordance with rotating machine voltage commands v _u *, v _v *, and v _w * supplied from the controller 5 .

The position estimator 4 calculates an estimated rotor position using the rotating machine currents _iu , _iv , and _iw detected by the current detector 2 and a gate signal from the voltage applicator 3, which will be described later. In the following description, the rotor position is represented as "θ", and the estimated value of the rotor position θ is represented by adding "^" above "θ". Note that a symbol with "^" above "θ" can also be represented by adding "^" after "θ". Similarly, a symbol with "^" above or after a symbol representing a parameter represents the estimated value of that parameter. The position estimator 4 outputs the estimated rotor position θ^ to the controller 5.

The controller 5 calculates rotating machine voltage commands _vu *, vv*, _vw * to drive the rotating machine 1 so that the rotating machine currents _id , _iq on the rotating coordinates of the rotating machine 1 become values indicated by the rotating machine current commands _id *, _iq * on the _rotating coordinates, and outputs the calculated rotating machine voltage commands _vu *, _vv *, _vw * to the voltage applicator 3.

Figure 2 is a diagram showing an example of the circuit configuration of the voltage applicator 3 shown in Figure 1. Figure 2 shows an example of the circuit configuration when the voltage applicator 3 is a three-phase PWM inverter. The voltage applicator 3 has leg 30A in which the upper arm semiconductor element UP and the lower arm semiconductor element UN are connected in series, leg 30B in which the upper arm semiconductor element VP and the lower arm semiconductor element VN are connected in series, and leg 30C in which the upper arm semiconductor element WP and the lower arm semiconductor element WN are connected in series. Leg 30A, leg 30B, and leg 30C are connected in parallel with each other.

A bus voltage is applied to the voltage applicator 3 via the DC buses 35a and 35b. The voltage applicator 3 converts the DC power of the power source 36 supplied via the DC buses 35a and 35b into AC power, and supplies the converted AC power to the rotating machine 1 to drive it. Note that the current detector 2 is omitted from Figure 2.

Figure 2 illustrates an example in which the semiconductor elements UP, UN, VP, VN, WP, and WN are metal-oxide-semiconductor field-effect transistors (MOSFETs). Each of the semiconductor elements UP, UN, VP, VN, WP, and WN includes a transistor 30a and a diode 30b connected in anti-parallel to the transistor 30a. "Connected in anti-parallel" means that the anode side of the diode is connected to a first terminal corresponding to the source of the MOSFET, and the cathode side of the diode is connected to a second terminal corresponding to the drain of the MOSFET.

In addition, the semiconductor elements UP, UN, VP, VN, WP, and WN may be, for example, insulated gate bipolar transistors (IGBTs) instead of MOSFETs.

Connection point 32 between semiconductor element UP of the upper arm and semiconductor element UN of the lower arm is connected to the first phase of the rotating machine 1, for example, the u-phase. Connection point 33 between semiconductor element VP of the upper arm and semiconductor element VN of the lower arm is connected to the second phase of the rotating machine 1, for example, the v-phase. Connection point 34 between semiconductor element WP of the upper arm and semiconductor element WN of the lower arm is connected to the third phase of the rotating machine 1, for example, the w-phase. In voltage applicator 3, connection points 32, 33, and 34 form AC terminals.

Here, the voltage vector output by the voltage applicator 3 will be described. As described above, the voltage applicator 3 is a three-phase PWM inverter, a power converter that obtains a desired voltage by PWM-controlling the power source 36 supplied via DC buses 35a and 35b. The three-phase PWM inverter has two switching elements, one above the other, per phase, and operates so that one of the upper and lower switching elements is on. Therefore, a three-phase triangular wave comparison inverter has 2⅔, or eight, switching states. Here, the states of the gate signals of the upper arms of the u, v, and w phases of the voltage applicator 3 are defined as _Gu , _Gv , and _Gw, respectively. When the value of _Gu , _Gv , or _Gw is 1, it means that the semiconductor element of the upper arm of the corresponding phase is conductive, and when the value of _Gu , _Gv , _{or Gw} is 0, it means that the semiconductor element of the lower arm of the corresponding phase is conductive. For example, when ( _Gu , _Gv , _Gw ) = (1, 0, 0), the semiconductor element of the u-phase upper arm is conductive, and the semiconductor elements of the v-phase and w-phase lower arms are conductive.

Here, the voltage vectors in the eight switching states of the voltage applicator 3 are defined as _V0 to _V7 . Figure 3 is a diagram showing an example of the correspondence between the switching states of each phase of the voltage applicator 3 shown in Figure 1 and the definitions of the voltage vectors. Under the condition (G _u , G _v , G _w ) = (0, 0, 0), the applied voltage vector is defined as _V0 ; under the condition (G _u , G _v , G _w ) = (1, 0, 0), the applied voltage vector is defined as _V1 ; under the condition (G _u , G _v , G _w ) = (1, 1, 0), the applied voltage vector is defined as _V2 ; and under the condition (G _u , G _v , G _w ) = (0, 1, 0), the applied voltage vector is defined as _V3 . Furthermore, when ( _Gu , _Gv , _Gw ) = (0, 1, 1), the applied voltage vector is defined as _V4 ; when ( _Gu , _Gv , _Gw ) = (0, 0, 1), the applied voltage vector is defined as _V5 ; when ( _Gu , _Gv , _Gw ) = (1, 0, 1), the applied voltage vector is defined as _V6 ; and when ( _Gu , _Gv , _Gw ) = (1, 1, 1), the applied voltage vector is defined as _V7 . Of these eight voltage vectors _V0 to _V7 , voltage vectors _V0 and _V7 are referred to as zero-voltage vectors, and the others, i.e., voltage vectors _V1 to _V6 , are referred to as effective voltage vectors. Note that voltage vectors _V0 to _V7 may also be referred to as voltage vectors V0 _{to V7} . Similarly, the effective voltage vectors V ₁ to V ₆ may be expressed as effective voltage vectors V _{1 to V 6} .

Figure 4 shows the eight switching states and voltage vectors shown in Figure 3. Figure 4 shows the voltage vectors in each switching state and the conduction state of each semiconductor element of the voltage applicator 3.

5 is a diagram for explaining signal processing in the position estimator 4 shown in Fig. 1. The position estimator 4 calculates an estimated rotor position θ^, which is an estimate of the position of the rotor of the rotating machine 1, using the rotating machine currents _iu , _iv , and _iw detected by the current detector 2 and the gate signals _Gu , _Gv , and _Gw of the voltage applicator 3. Specifically, the position estimator 4 has a current differential information calculation unit 40, a classifier 41, a DC component remover 42, a three-phase to two-phase converter 43, and a phase synchronization calculation unit 44.

The current differential information calculation unit 40 calculates current differential information corresponding to each of the effective voltage vectors _V1 to _V6 . The current differential information calculation unit 40 calculates current differential information corresponding to each of the effective voltage vectors _V1 to _V6 for the u-phase, v-phase, and w-phase rotating machine currents _iu , _iv , and _iw . Therefore, the current differential information calculation unit 40 outputs 3 x 6 = 18 types of current differential information. The current differential information is also called the rotating machine current change amount. The current differential information calculation unit 40 receives gate signals _Gu , _Gv , and _Gw of the semiconductor elements in the upper arms of the voltage applicator 3 for each phase, and the rotating machine currents _iu , _iv , and _iw .

Fig. 6 is a diagram showing a detailed configuration of the current differential information calculation unit 40 shown in Fig. 5. The current differential information calculation unit 40 has a voltage vector determiner 400 that determines the type of voltage vector output by the voltage applicator 3, and a current differential calculator 401 that calculates current differential information of each phase corresponding to the effective voltage vector using the determination result of the voltage vector determiner 400 and the rotating machine currents _iu , _iv , and _iw .

3, the voltage vector determiner 400 determines the type of voltage vector output by the voltage applicator 3 from the gate signals G _u , G _v , and G _w of the semiconductor elements in the upper arm of each phase of the voltage applicator 3. The voltage vector determiner 400 determines which of the voltage vectors V _{0 to} V 7 the type of voltage vector is from the values of the gate signals G _u , G _v , and G _w , and outputs the voltage vector V _{0 to} V 7, which is the determination result, to the current differential calculator 401.

The current differential calculator 401 calculates current differential information for each phase corresponding to each of the effective voltage vectors V1 _{to V6} based on the voltage vectors _{V0 to V7} , which are the determination results of the voltage vector determiner 400, and the rotating machine currents _iu , _iv , and _iw . The current differential calculator 401 stores the type of the current voltage vectors V0 _{to V7} and the type of the voltage vector from one control cycle ago, and if the same effective voltage vector appears for two or more control cycles, calculates current differential information for each phase corresponding to the type of that effective voltage vector. The control cycle is set to a value sufficiently shorter than the period of the triangular wave carrier of the voltage applicator 3, in order to sample the current at two or more points while the effective voltage vector is being applied. If the type of the current voltage vector is _VN and the type of the voltage vector one control cycle ago was _VN , the current differential calculator 401 calculates the current differential information of the u-phase, v-phase, and w-phase when _VN is applied as "di _uVN /dt,""di _vVN /dt," and "di _wVN /dt," respectively. N is an integer from 1 to 6. The current differential calculator 401 distinguishes between the six types of effective voltage vectors V1 _{to V6} and the three-phase current differential information, and outputs 18 types of current differential information: "di _uV1-6 /dt,""di _vV1-6 /dt," and "di _wV1-6 /dt."

Here, a total of 18 types of current differential information output by the current differential calculator 401 will be described. The current differential information includes a DC component and an AC component. FIG. 7 is a diagram showing the DC component and AC component included in the current differential information. In FIG. 7, for each of the 18 types of current differential information, a signal name, a mathematical expression indicating the DC component, and a mathematical expression indicating the AC component are associated. In the "signal name," u, v, and w indicate the corresponding phase of the rotating machine 1, and _V1 to _V6 indicate the type of the corresponding effective voltage vector.

The characteristics of the "DC component" of the current differential information shown in Figure 7 will be described. Here, if A is defined by the following mathematical formula (1), the "DC component" of the current differential information occurs in the phase in the direction of the effective voltage vector with a magnitude of "2/A" and occurs in the phases other than the phase in the direction of the effective voltage vector with a magnitude of "1/A" with an opposite sign. Therefore, the sum of the DC component of the u-phase, the DC component of the v-phase, and the DC component of the w-phase when the same effective voltage vector is applied is zero. Here, _Vdc is the DC voltage of the power source 36 of the voltage applicator 3.

_L0 in formula (1) is expressed by the following formula (2): _L1 in formula (1) is expressed by the following formula (3): Here, _Ld is the d-axis inductance of the rotating machine 1, and _Lq is the q-axis inductance of the rotating machine 1.

Next, we will explain the characteristics of the "AC component" of the current differential information. Here, if the number of the effective voltage vector is N, the AC component of the current differential information for the u phase is expressed by equation (4), the AC component of the current differential information for the v phase is expressed by equation (5), and the AC component of the current differential information for the w phase is expressed by equation (6).

As shown in equations (4) to (6), the current differential information obtained by applying an effective voltage vector contains information about the rotor position θ. The "AC Component" column in Figure 7 shows the expansion of the phases in equations (4) to (6). As is clear from Figure 7 and equations (4) to (6), the AC components of the current differential information during the period when the same effective voltage vector is applied have a phase difference of ±2π/3, and each reference phase shifts depending on the application direction of the effective voltage vector. The magnitude of the amplitude of the AC component is the same for all combinations of effective voltage vectors and phases, and is equal to (1/A) × ( _L1 / _L0 ). Note that, since the magnitude relationship between the d-axis and q-axis inductances differs between an interior permanent magnet synchronous motor (IPMSM) and a synchronous reluctance motor, the value of the cosine function coefficient "(1/A) x ( _L1 / _L0 )" is a positive value in an interior permanent magnet synchronous motor and a negative value in a synchronous reluctance motor.

In each phase, the current differential information obtained by combinations of effective voltage vectors that are related in the direction of magnetization and demagnetization has a relationship of opposite signs, as expressed in the following equations (7) to (9). In equations (7) to (9), n is an integer from 1 to 3. The combinations of voltage vectors that are related in the direction of magnetization and demagnetization are V1 and V4 in the u-phase, V3 and V6 in the v-phase, and V5 and V2 in the w-phase.

Figure 8 shows the output of the current differential information calculation unit 40 shown in Figure 5. Figure 8 shows the simulation results of current vector control for a synchronous reluctance motor rotating at low speed. The PWM of the voltage applicator 3 uses a commonly used triangular wave carrier comparison common to all three phases. For illustrative purposes, voltage vector numbers V0 and V7 are numbered 0. Focusing on the rotor position and the applied voltage vector numbers, a correlation can be confirmed between the rotor position and the voltage vector appearance pattern. During the period when a specific effective voltage vector appears, current differential information corresponding to other effective voltage vectors cannot be obtained. Therefore, in the appearance pattern of an effective voltage vector in which a specific effective voltage vector occurs over a long period of time, the current differential information is fragmented. Furthermore, the timing at which each current differential information can be obtained varies, and the delay amount varies depending on the signal. Due to this characteristic, position sensorless control becomes unstable if signal processing is performed without considering the voltage vector appearance pattern. Here, "signal processing is performed without taking into consideration the appearance pattern of voltage vectors" refers to, for example, fixing the type of current differential information used to estimate the rotor position regardless of the type of voltage vector that appears.

For this reason, the position estimator 4 performs signal processing to generate, from the fragmented current differential information, the AC component of continuous current differential information that contains rotor position information. The signal processing method performed by the position estimator 4 is explained below. The current differential information has the characteristics shown in equations (4) to (9) above. By utilizing this characteristic, the same waveform shape appears in the current differential information under different voltage vector and phase conditions. For this reason, the position estimator 4 uses the waveform shapes that appear under different voltage vector and phase conditions to interpolate the fragmented current differential information and generate the AC component of continuous current differential information.

Returning to the explanation of Figure 5, the classifier 41 classifies the current differential information output by the current differential information calculation unit 40 into one of six types of signals based on the magnitude of the DC component and the reference phase. Based on the characteristics of the above equations (4) to (9), the classifier 41 classifies the information into six types based on the magnitude of the DC component and the phase of the AC component: group (2/A, 0°), group (-1/A, 120°), group (-1/A, -120°), group (2/A, -120°), group (-1/A, 0°), and group (2/A, 120°).

Figure 9 is a diagram explaining the classification performed by classifier 41. Figure 9 shows the "group," "DC component," "AC component," and "symbol" for each of the six groups classified by classifier 41. Here, "group" refers to the name of the group, and a group described as group (X, Y°) refers to a group with a DC component of X and a reference phase of the AC component of Y°. For example, the reference phase Y for the cosine component of the AC component "cos(2θ + 2π/3)" in Figure 9 is 2π/3 [rad] = 120 [°]. The "symbol" indicates signals with the same waveform. For example, in group (2/A, 0°), the waveform of the current differential information for the u phase when the effective voltage vector V1 is applied is the same as the waveform of the current differential information for the u phase when the effective voltage vector V4 is applied.

FIG. 10 is an explanatory diagram of the operation of the classifier 41 shown in FIG. 5. When the classifier 41 receives the current differential information "di _uV1-6 /dt,""di _{vV1-6 /} dt," and "di _wV1-6 /dt," it generates six types of signals based on the classification shown in FIG. 9. Specifically, the classifier 41 prepares variables corresponding to each of the six groups, assigns the current differential information to the variables of the group into which the current differential information input to the classifier 41 is classified, and maintains the previous values of the variables of the other groups. Here, for the sake of explanation, the names of the groups are used as variable names. Let group(X, Y°) be the variable of the group whose DC component is X and whose reference phase of the AC component is Y°. For example, the classifier 41 assigns "di _uV1 /dt" to group (2/A, 0°) when V1 is applied, assigns "-di _uV4 /dt" when V4 is applied, and operates to hold the previous value when an effective voltage vector other than V1 and V4, i.e., V2, V3, V5, or V6, is applied. Similarly, the classifier 41 assigns "di _vV1 /dt" to group (-1/A, 120°) when V1 is applied, assigns "-di _vV4 /dt" when V4 is applied, assigns "di _uV3 /dt" when V3 is applied, and assigns "-di _uV6 /dt" when V6 is applied, and operates to hold the previous value when V2 and V5 are applied.

Returning to the explanation of Figure 5, the DC component remover 42 extracts a DC component from the output of the classifier 41 and subtracts the DC component from the current differential information obtained by applying the latest effective voltage vector, thereby generating a continuous AC component. In the first embodiment, an example of extracting a DC component using a three-phase balance condition is described. To extract the DC component "1/A" using a three-phase balance condition, the following equations (10) to (14) are used. That is, the DC component remover 42 calculates the sum of signals from the output of the classifier 41 that have phases of 0°, 120°, and -120°, and multiplies this by a conversion coefficient to a DC component to calculate the DC component. While five equations (10) to (14) are shown here, the DC component remover 42 can perform the calculation using at least one appropriate equation based on the combination of the latest effective voltage vector and the most recent effective voltage vector with a different number from the latest effective voltage vector.

Specifically, the DC component remover 42 uses one of the formulas (10) to (14) that uses the latest effective voltage vector and the most recent effective voltage vector with a different number from the latest effective voltage vector. Here, for example, group (2/A, 0°) is generated based on the current differential information when effective voltage vector V1 or V4 is applied, group (2/A, 120°) is generated based on the current differential information when effective voltage vector V5 or V2 is applied, and group (2/A, -120°) is generated based on the current differential information when effective voltage vector V3 or V6 is applied. Therefore, formula (10) can be said to be a formula that uses effective voltage vectors V1 or V4, V5 or V2, and V3 or V6. Similarly, formula (11) is a formula that uses effective voltage vectors V2 or V5 and V1 or V3 or V4 or V6. Equation (12) uses the effective voltage vectors V1 or V4 and V2 or V5. Equation (13) uses the effective voltage vectors V1 or V4 and V3 or V6. Equation (14) uses the effective voltage vectors V2 or V5 and V3 or V6.

For example, if the combination of the latest effective voltage vector and the most recent effective voltage vector with a different number from the latest effective voltage vector is V1 and V2, then at least one formula using these voltage vectors can be selected from formulas (10) to (14). The formulas using the effective voltage vectors V1 and V2 are formulas (11) and (12). Therefore, the DC component remover 42 calculates the DC component "1/A" using at least one of formulas (11) and (12). When multiple formulas are used, the DC component remover 42 can calculate the DC component "1/A" using the average value of the calculation results of each of the multiple formulas.

The DC component remover 42 then uses the extracted DC component to calculate the AC component of the latest current differential information by subtracting the DC component from the current differential information obtained by applying the latest effective voltage vector. The DC component remover 42 can calculate the AC component of the latest current differential information using the following equations (15) to (17). The DC component remover 42 selects one of equations (15) to (17) based on the type of the latest voltage vector.

The DC component remover 42 outputs the calculation results, group (0, 0°), group (0, 120°), and group (0, -120°), to the three-phase to two-phase converter 43. The outputs of the DC component remover 42, group (0, 0°), group (0, 120°), and group (0, -120°), are continuous AC components containing rotor position information. Below, we will explain how to calculate the rotor position using these AC components. To calculate the rotor position from AC components that have a phase difference of ±2π/3 from each other, there are several methods, including three-phase to two-phase conversion of these AC components and performing arctangent calculations, and performing phase-synchronous calculations on the three-phase to two-phase conversion results to estimate the rotor position. Here, we will explain the method of estimating the rotor position using phase-synchronous calculations as an example.

The three-phase to two-phase converter 43 calculates the α-axis AC component α and the β-axis AC component β, which are AC components on two orthogonal axes. The three-phase to two-phase converter 43 calculates the α-axis AC component α and the β-axis AC component β using the following equation (18), and outputs the calculated α-axis AC component α and β-axis AC component β to the phase synchronization calculation unit 44.

The phase synchronization calculation unit 44 estimates the rotor position of the rotating machine 1 based on the α-axis AC component α and the β-axis AC component β output by the three-phase to two-phase converter 43. Specifically, the phase synchronization calculation unit 44 estimates the rotor position of the rotating machine 1 by performing a phase synchronization calculation on the α-axis AC component α and the β-axis AC component β.

Figure 11 is a block diagram showing the configuration of the phase synchronization calculation unit 44 shown in Figure 5. The phase synchronization calculation unit 44 has a phase error calculation unit 441, a PI (Proportional Integral) controller 442, an integrator 443, and proportional controllers 444 and 445.

The phase error calculation unit 441 receives the α-axis AC component α and β-axis AC component β output by the three-phase to two-phase converter 43, and the estimated rotor position 2θ^ output by the integrator 443. The phase error calculation unit 441 calculates the phase error Δi _AC *Δ2θ according to the following equation (19). The phase error calculation unit 441 outputs the calculated phase error Δi _AC *Δ2θ to the PI controller 442.

Here, "Δi _AC " in equation (19) is expressed by the following equation (20).

The phase error Δi _AC *Δ2θ output from the phase error calculation unit 441 is input to the PI controller 442. The PI controller 442 outputs an estimated speed 2ω^ so that the phase error Δi _AC *Δ2θ becomes zero.

The integrator 443 integrates the estimated speed 2ω^ output by the PI controller 442 and outputs the integrated value as the estimated rotor position 2θ^. The estimated rotor position 2θ^ output by the integrator 443 is fed back to the phase error calculation unit 441.

In the above equation (19), when "2θ >2θ^", the phase error Δi _AC *Δ2θ takes a positive value, and therefore the estimated speed 2ω^ and the estimated rotor position 2θ^ are corrected in an increasing direction. Furthermore, when "2θ <2θ^", the phase error Δi _AC *Δ2θ takes a negative value, and therefore the estimated speed 2ω^ and the estimated rotor position 2θ^ are corrected in a decreasing direction. Ultimately, "2θ = 2θ^" is satisfied, and the phase and frequency of the AC component of the current differential information of the rotating machine 1 are estimated. In this way, the phase synchronization calculation unit 44 takes the form of a phase locked loop (PLL).

The phase synchronization calculation unit 44 inputs the estimated rotor position 2θ^ into the proportional unit 444 and multiplies it by 0.5 to calculate the estimated rotor position θ^. The phase synchronization calculation unit 44 also inputs the estimated speed 2ω^ into the proportional unit 445 and multiplies it by 0.5 to calculate the estimated speed ω^.

Figure 12 shows the output of each part of the position estimator 4 shown in Figure 5. In Figure 12, the operating conditions are the same as those in Figure 8, which are conditions under which the current differential information is fragmented. The "Rotor Position" column in the first row from the top of Figure 12 shows the true rotor position and the estimated position output by the phase synchronization calculation unit 44. The second to fourth rows from the top of Figure 12 show the output of the current differential information calculation unit 40. The fifth row from the top of Figure 12 shows the output of the classifier 41. The sixth row from the top of Figure 12 shows the output of the DC component remover 42. The seventh row from the top of Figure 12 shows the output of the three-phase to two-phase converter 43. The eighth row from the top of Figure 12 shows the numbers of the voltage vectors applied at each point in time. Note that, as in Figure 8, for the sake of explanation, voltage vectors V0 and V7 are numbered 0 in Figure 12.

From Figure 12, it can be seen that the classifier 41 generates six types of signals based on the classification shown in Figure 9. Furthermore, the output of the DC component remover 42 is an AC component expressed on two orthogonal axes with zero DC component and vibrating at twice the angle of the rotor position. The position estimator 4 estimates the rotor position by performing phase-synchronous calculations on the output of the three-phase to two-phase converter 43.

Returning to the explanation of Fig. 1, the rotating machine currents _iu , _iv , and _iw detected by the current detector 2 are input to the three-phase to two-phase converter 9 of the controller 5. The three-phase to two-phase converter 9 converts the rotating machine currents _iu , _iv , and _iw on the three-phase coordinate system into rotating machine currents _iα and _iβ on the stationary two-phase coordinate system. The three-phase to two-phase converter 9 outputs the rotating machine currents _iα and _iβ to the rotating coordinate converter 10.

The rotating coordinate converter 10 receives the rotating machine currents _iα and _iβ output by the three-phase to two-phase converter 9 and the estimated rotor position θ^ output by the position estimator 4. Using the estimated rotor position θ^, the rotating coordinate converter 10 converts the rotating machine currents _iα and _iβ on the stationary two-phase coordinates into rotating machine currents _id and _iq on the rotating coordinates. The rotating coordinate converter 10 outputs the rotating machine currents _id and _iq to the current controller 6.

The current controller 6 receives rotating machine current commands _id *, _iq * and rotating machine currents _id , _iq . The rotating machine current command _id * is a d-axis drive current command indicating the armature current component in the d-axis direction at which the magnetic resistance of the rotor of the rotating machine 1 is smallest. The rotating machine current command _iq * is a q-axis drive current command indicating the armature current component in the 1-axis direction, which is perpendicular to the d-axis. The current controller 6 controls the current so that the rotating machine currents _id , _iq output from the rotating coordinate converter 10 become the rotating machine current commands _id *, _iq *, and calculates rotating machine voltage commands _vd *, _vq * on the rotating coordinates. The current control in the current controller 6 is, for example, PI control. The current controller 6 outputs the calculated rotating machine voltage commands _vd *, _vq * to the rotating coordinate inverter 7.

The rotating coordinate inverse converter 7 receives the rotating machine voltage commands v _d *, v _q * and the estimated rotor position θ^. Using the estimated rotor position θ^, the rotating coordinate inverse converter 7 converts the rotating machine voltage commands v _d *, v _q * on the rotating coordinates calculated by the current controller 6 into rotating machine voltage commands v _α *, v _β * on the stationary two-phase coordinates. The rotating coordinate inverse converter 7 outputs the rotating machine voltage commands v _α *, v _β * to the two-phase to three-phase converter 8.

The rotating machine voltage commands v _α *, v _β * are input to the two-phase to three-phase converter 8. The two-phase to three-phase converter 8 converts the rotating machine voltage commands v _α *, v _β * on the stationary two-phase coordinate system into rotating machine voltage commands v _u *, v _v *, v _w * on the three-phase coordinate system for driving the rotating machine 1.

As described above, the control device 100 according to the first embodiment is a control device 100 that performs drive control of a polyphase rotating machine 1, and includes a current detector 2 that is a current detection unit that detects a rotating machine current flowing through the rotating machine 1, a controller 5 that is a drive voltage command calculation unit that generates a drive voltage command for driving the rotating machine 1 based on information about the rotating machine current and the rotor position of the rotating machine 1, a voltage applicator 3 that applies a voltage to the rotating machine 1 based on the generated drive voltage command, and a position estimator 4 that is a position estimator that estimates the rotor position based on the rotating machine current detected by the current detector 2. The position estimator 4 determines the type of voltage vector output by the voltage applicator 3 based on the gate signals _Gu , _Gv , and _Gw of the voltage applicator 3, calculates current differential information that is the amount of change in the rotating machine current for each determined type of voltage vector, generates an AC signal that has zero DC component and changes at an angle twice the rotor position from the amount of change in the rotating machine current that is the calculation result, and estimates the rotor position based on the generated AC signal. With this configuration, the control device 100 can estimate the rotor position with high accuracy even in an appearance pattern of an effective voltage vector in which the current differential information is fragmented, by generating a continuous AC signal with zero DC component and oscillating at twice the angle of the rotor position from the fragmented current differential information.

The position estimator 4 can estimate the rotor position, for example, by performing phase-synchronous calculations on the generated AC signal. Furthermore, the position estimator 4 generates an AC signal with a continuous waveform based on a combination of multiple pieces of current differential information, including the same waveform, obtained under multiple conditions where at least one of the voltage vector and phase is different. More specifically, the position estimator 4 utilizes the characteristic that two pieces of current differential information obtained under conditions where the voltage vector directions are opposite to each other and the same phase have opposite signs to each other, and can generate a continuous AC signal using a value obtained by multiplying one of the two pieces of current differential information obtained under conditions where the voltage vector directions are opposite to each other and the same phase by -1.

The position estimator 4 can generate a continuous AC signal by utilizing the characteristic that the phase of the AC component of the current differential information shifts depending on the direction of the voltage vector.

Furthermore, as shown in the above equations (10) to (14), the position estimator 4 can calculate the DC component of the current differential information by taking the sum of the first current differential information, the second current differential information having a phase difference of plus 2/3π from the first current differential information, and the third current differential information having a phase difference of minus 2/3π from the first current differential information.

The position estimator 4 also has a phase error calculation unit 441 that calculates a phase error based on an AC signal that has zero DC component and changes at twice the angle of the rotor position and the estimated rotor position, a PI controller 442 that is an estimated speed generation unit that outputs an estimated speed based on the phase error, and an integrator 443 that outputs the value obtained by integrating the estimated speed as the estimated position.

Embodiment 2.
The control device 100 according to the second embodiment has the same configuration as that of the first embodiment. In the second embodiment, the overall configuration of the control device 100 is the same as that shown in FIG. 1, and the configuration of the position estimator 4 is the same as that shown in FIG. 5. Therefore, the same reference numerals as those in the first embodiment will be used in the description of the second embodiment. However, in the second embodiment, the processing content performed by the DC component remover 42 shown in FIG. 5 differs from that in the first embodiment. The following description will mainly focus on the differences from the first embodiment.

In embodiment 2, the DC component remover 42 calculates the DC component "1/A" using the following equations (21) to (23) instead of the above equations (10) to (14).

In equations (21) to (23), the DC component "1/A" is calculated by taking the difference between signals output by the classifier 41 that have different DC components and the same reference phase for the AC component. While three equations (21) to (23) are shown here, the DC component remover 42 only needs to use at least one equation that uses the latest effective voltage vector and the most recent effective voltage vector with a different number from the latest effective voltage vector. For example, group (2/A, 0°) is generated based on the current differential information when effective voltage vector V1 or V4 is applied, and group (-1/A, 0°) is generated based on the current differential information when effective voltage vector V2, V3, V5, or V6 is applied. Therefore, equation (21) can be considered to be an equation that uses effective voltage vector V1 or V4 and V2, V3, V5, or V6. Similarly, equation (22) is an equation using the effective voltage vectors V2 or V5 and V1 or V3 or V4 or V6, and equation (23) is an equation using the effective voltage vectors V3 or V6 and V1 or V2 or V4 or V5.

For example, if the latest effective voltage vector and the most recent effective voltage vector with a different number from the latest effective voltage vector are effective voltage vectors V1 and V2, the calculation is performed using at least one of Equation (21) and Equation (22), which use effective voltage vectors V1 and V2. As in embodiment 1, when multiple equations are used, the DC component remover 42 can calculate the DC component "1/A" using the average value of the calculation results of each of the multiple equations. Thus, in embodiment 2, the process for extracting the DC component differs from embodiment 1, but the other processes are the same as in embodiment 1. In embodiment 2, as in embodiment 1, the control device 100 can estimate the rotor position with high accuracy even in an appearance pattern of effective voltage vectors in which the current differential information is fragmented by generating a continuous AC signal with zero DC component and oscillating at twice the rotor position angle from the fragmented current differential information.

Furthermore, while the formulas (10) to (14) used in embodiment 1 require three signals from the output of classifier 41, the formulas (21) to (23) used in embodiment 2 can calculate the DC component "1/A" using two signals from the output of classifier 41. Therefore, embodiment 2 has the advantage of reducing the computational load compared to embodiment 1. Furthermore, the method using formulas (21) to (23) requires the application of two types of voltage vectors, while the method using formulas (10) to (14) requires the application of two or three types of voltage vectors. From the perspective of position estimation response, the fewer types of voltage vectors used in the calculation, the better the responsiveness. Therefore, embodiment 2 can extract the DC component with higher response than the method of embodiment 1.

Next, we will explain the hardware configuration for realizing each function of the control device 100 according to the first and second embodiments. The functions referred to here refer to the functions of the current detector 2, voltage applicator 3, position estimator 4, and controller 5.

13 is a diagram illustrating a first example of a hardware configuration for realizing the functions of the control device 100 according to the first and second embodiments. FIG. 14 is a diagram illustrating a second example of a hardware configuration for realizing the functions of the control device 100 according to the first and second embodiments. In the first example illustrated in FIG. 13, the control device 100 has a dedicated processing circuit 1000, a current detector 2, and a voltage applicator 3. Here, the functions of the current detector 2 and the voltage applicator 3 are each realized using dedicated hardware, and the functions of the position estimator 4 and the controller 5 are realized by the dedicated processing circuit 1000. Also, in the second example illustrated in FIG. 14, the control device 100 has a processor 1001, a memory device 1002, a current detector 2, and a voltage applicator 3. Here, the functions of the current detector 2 and the voltage applicator 3 are each realized using dedicated hardware, and the functions of the position estimator 4 and the controller 5 are realized by the processor 1001 and the memory device 1002. The dedicated processing circuit 1000 and the processor 1001 are also referred to as control circuits.

The dedicated processing circuit 1000 may be a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination of these. The control device 100 may implement all of the above functions using a single dedicated processing circuit 1000, or may implement each of the above functions using multiple dedicated processing circuits 1000.

The processor 1001 can realize each function of the control device 100 by reading and executing a program stored in the memory device 1002. Note that the control device 100 may realize each of the above-mentioned functions by having multiple processors 1001 and multiple memory devices 1002 work together.

When using the processor 1001 and the storage device 1002, each of the above-mentioned functions is realized by software, firmware, or a combination of these. The software or firmware is written as a program and stored in the storage device 1002. The processor 1001 reads and executes the program stored in the storage device 1002. These programs can also be said to cause the computer to execute the procedures and methods for performing each function.

The processor 1001 is a CPU, also known as a processing unit, arithmetic unit, microprocessor, microcomputer, DSP (Digital Signal Processor), etc. The storage device 1002 is, for example, a non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable ROM), EEPROM (registered trademark) (Electrically EPROM), a magnetic disk, a flexible disk, an optical disk, a compact disk, a minidisk, a DVD (Digital Versatile Disk), etc.

The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. Parts of the configuration may also be omitted or modified without departing from the spirit of the invention.

For example, in the above-described first and second embodiments, the rotating machine 1 is a synchronous reluctance motor, but the type of rotating machine 1 is not limited to this. The rotating machine 1 may also be a motor with salient poles, such as an interior permanent magnet synchronous motor or a surface permanent magnet synchronous motor (SPMSM).

In addition, in the above-mentioned embodiments 1 and 2, the controller 5 of the control device 100 controls the d-axis current and the q-axis current, but the controller 5 can also be configured to control torque, rotational speed, etc.

Furthermore, in the above-mentioned first and second embodiments, a configuration in which the current detector 2 detects the phase current of the rotating machine 1 has been described, but the current detector 2 is an example of a current detection unit and is not limited to the above example. The current detection unit only needs to be able to detect the phase current, and may be a current sensor built into an inverter (not shown) that constitutes the voltage applicator 3.

1 Rotating machine, 2 Current detector, 3 Voltage applicator, 4 Position estimator, 5 Controller, 6 Current controller, 7 Rotating coordinate inverse converter, 8 Two-phase to three-phase converter, 9, 43 Three-phase to two-phase converter, 10 Rotating coordinate converter, 30a Transistor, 30b Diode, 30A, 30B, 30C Leg, 32, 33, 34 Connection point, 35a, 35b DC bus, 36 Power source, 40 Current differential information calculation unit, 41 Classifier, 42 DC component remover, 44 Phase synchronization calculation unit, 100 Control device, 400 Voltage vector determiner, 401 Current differential calculator, 441 Phase error calculation unit, 442 PI controller, 443 Integrator, 444, 445 Proportional regulator, 1000 Dedicated processing circuit, 1001 Processor, 1002 Memory device, UP, UN, VP, VN, WP, WN semiconductor elements.

Claims (10)

A control device for performing drive control of a multi-phase rotating machine having salient poles ,
a current detection unit that detects a rotating machine current flowing through the rotating machine;
a drive voltage command calculation unit that generates a drive voltage command for driving the rotating machine based on the rotating machine current and an estimated value of a rotor position of the rotating machine;
a voltage applicator that applies a voltage to the rotating machine based on the generated drive voltage command;
a position estimation unit that estimates the rotor position based on the rotating machine current;
Equipped with
the position estimation unit determines a type of voltage vector output by the voltage applicator based on a gate signal of the voltage applicator, calculates a change in the rotating machine current for each determined type of voltage vector, generates an AC signal having zero DC component and changing at twice the angle of the rotor position based on the calculated change in the rotating machine current, and estimates the rotor position based on the AC signal. The control device according to claim 1 , wherein the position estimation unit estimates the rotor position by performing a phase synchronous operation on the AC signal. 2. The control device according to claim 1, wherein the position estimation unit generates the AC signal having a continuous waveform based on a combination of a plurality of the rotating machine current change amounts including the same waveform shape, among a plurality of the rotating machine current change amounts obtained under a plurality of conditions in which at least one of a voltage vector and a phase is different. 4. The control device according to claim 3, wherein the position estimation unit utilizes a feature that the two rotating machine current change amounts obtained under the same phase condition with voltage vectors in opposite directions to each other have opposite signs to each other, and generates the AC signal using a value obtained by multiplying one of the two rotating machine current change amounts obtained under the same phase condition with voltage vectors in opposite directions to each other by minus one. The control device according to claim 3 , wherein the position estimation unit generates the AC signal by utilizing a characteristic that a phase of an AC component of the amount of change in the rotating machine current shifts depending on the direction of a voltage vector. 6. The control device according to claim 3, wherein the position estimation unit calculates a DC component of the rotating machine current change amount, calculates an AC component of the rotating machine current change amount by subtracting the calculated DC component from the rotating machine current change amount, and generates the AC signal based on the AC component. 7. The control device according to claim 6, wherein the position estimation unit calculates the DC component by taking the sum of a first rotating machine current change amount, a second rotating machine current change amount having a phase difference of plus 2/3π with respect to the first rotating machine current change amount, and a third rotating machine current change amount having a phase difference of minus 2/3π with respect to the first rotating machine current change amount, among the rotating machine current change amounts. 7. The control device according to claim 6, wherein the position estimation unit calculates the DC component by taking a difference between two of the rotating machine current change amounts, the two having AC components with the same phase but different DC components. The position estimation unit
a phase error calculation unit that calculates a phase error based on the AC signal having zero DC component and changing at twice the angle of the rotor position and the estimated rotor position;
an estimated velocity generating unit that outputs an estimated velocity based on the phase error;
an integrator that outputs a value obtained by integrating the estimated velocity as the estimated position;
The control device according to claim 1 , further comprising: A drive control method for a polyphase rotating machine having salient poles , comprising:
detecting a rotating machine current flowing through the rotating machine;
generating a drive voltage command for driving the rotating machine based on the rotating machine current and an estimated value of a rotor position of the rotating machine;
applying a voltage to the rotating machine based on the generated drive voltage command;
estimating the rotor position based on the rotating machine current;
Equipped with
a drive control method comprising: determining a type of voltage vector output by a voltage applicator that applies a voltage to the rotating machine based on a gate signal of the voltage applicator; calculating a change in the rotating machine current for each determined type of voltage vector; generating an AC signal having zero DC component and changing at twice the angle of the rotor position based on the calculated change in the rotating machine current; and estimating the rotor position based on the AC signal.