JP2024168933A - Control device - Google Patents

Abstract

To improve the accuracy of detecting step-out in position sensorless control.SOLUTION: A control device includes a γ-δ current command value output unit 52 which selectively outputs, as a γ-axis current command value I*γ and a δ-axis current command value I*δ, a γ-axis current command value I*γ1 and a δ-axis current command value I*δ1, a γ-δ current command value I*γ2 and a δ-axis current command value I*δ2 calculated on the basis of the angular velocity command value ω*, a γ-δ voltage command value calculation unit 53 which calculates a γ-axis voltage command value V*γ on the basis of the γ-axis current value Iγ and the γ-axis current command value I*γ, and calculates the δ-axis voltage command value V*δ on the basis of the δ-axis current value Iδ and the δ-axis current command value I*δ, and a detection unit 56 that detects a step-out of the motor on the basis of an estimated position error Δθ^re calculated on the basis of the γ-axis voltage command value V*γ and the δ-axis voltage command value V*δ when the γ-axis current command value I*γ2 and the δ-axis current command value I*δ2 are output.SELECTED DRAWING: Figure 2

Description

This disclosure relates to a control device.

Position sensorless control is known, which controls a motor without using a position sensor. In position sensorless control, if the electrical angle error between the d axis of the d-q coordinate system and the γ axis of the γ-δ coordinate system becomes large, a step-out occurs, making it impossible to control the motor. Patent Document 1 describes a drive device that calculates the magnetic flux of a motor based on the current value flowing through the motor, motor parameters, and a motor rotation speed command value (angular velocity command value), and determines that the motor has stepped out when the calculated value falls below a threshold value.

JP 2008-92787 A

In the drive device described in Cited Document 1, out-of-step is detected using motor parameters and the angular velocity command value of the motor. Therefore, if an error occurs in the motor parameters or the angular velocity command value, there is a risk that the accuracy of detecting out-of-step may decrease.

This disclosure describes a control device that can improve the accuracy of detecting out-of-step in position sensorless control.

A control device according to one aspect of the present disclosure is a device that generates a drive signal to control an inverter that drives a motor. This control device includes a current value conversion unit that converts a current flowing through the motor into a γ-axis current value and a δ-axis current value, a γ-δ current command value output unit that selectively outputs, as a γ-axis current command value and a δ-axis current command value, a first γ-axis current command value and a first δ-axis current command value calculated based on an angular velocity command value of the motor, and a second γ-axis current command value and a second δ-axis current command value of zero amperes, and a γ-δ current command value output unit that calculates a γ-axis voltage command value based on the γ-axis current value and the γ-axis current command value, and a δ-axis voltage command value based on the δ-axis current value and the δ-axis current command value. The system includes a γ-δ voltage command value calculation unit that calculates a voltage command value, a drive signal output unit that converts the γ-axis voltage command value and the δ-axis voltage command value into a drive signal, and a detection unit that detects motor out-of-step based on an estimated position error that is an estimate of the position error between the γ-axis of the γ-δ coordinate system and the d-axis of the d-q coordinate system and is calculated based on the γ-axis voltage command value and the δ-axis voltage command value when the second γ-axis current command value and the second δ-axis current command value are output as the γ-axis current command value and the δ-axis current command value.

In the above control device, when the second γ-axis current command value and the second δ-axis current command value are output as the γ-axis current command value and the δ-axis current command value, the estimated position error is calculated based on the γ-axis voltage command value and the δ-axis voltage command value. Since the second γ-axis current command value and the second δ-axis current command value are current command values of zero amperes, when the second γ-axis current command value and the second δ-axis current command value are output as the γ-axis current command value and the δ-axis current command value, the γ-axis current value and the δ-axis current value converge to zero amperes. In this state, the extended induced voltage model on the γ-δ coordinate system becomes an equation that does not depend on the motor parameters and the estimated angular velocity. When the estimated position error is calculated using this extended induced voltage model, even if an error occurs in the motor parameters or the angular velocity command value, the estimated position error is not affected by the motor parameters and the angular velocity command value. By detecting the step-out of the motor based on the estimated position error calculated as described above, it is possible to prevent errors in the motor parameters and the angular velocity command value from affecting the detection accuracy of the step-out. This makes it possible to improve the accuracy of detecting out-of-step in position sensorless control.

This disclosure makes it possible to improve the accuracy of detecting out-of-step in position sensorless control.

FIG. 1 is a schematic configuration diagram of a control system including a control device according to an embodiment. FIG. 2 is a block diagram showing the functional configuration of the arithmetic unit shown in FIG. FIG. 3 is a diagram for explaining the relationship between the d-axis and the γ-axis.

The control device according to one embodiment will be described in detail below with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and duplicate descriptions will be omitted.

With reference to FIG. 1, a schematic configuration of a control system including a control device according to one embodiment will be described. FIG. 1 is a schematic configuration diagram of a control system including a control device according to one embodiment. The control system 1 shown in FIG. 1 is a system that performs position sensorless control of a motor (electric motor) M. The motor M is a position sensorless motor, for example, a permanent magnet synchronous motor (PMSM). The motor M is mounted on a vehicle such as an electric forklift or a plug-in hybrid vehicle. The control system 1 includes an inverter circuit 2 (inverter), a control device 3, and current sensors Se1, Se2, and Se3.

The inverter circuit 2 drives the motor M with DC power supplied from the DC power source PS. The inverter circuit 2 includes a capacitor C and switching elements SW1, SW2, SW3, SW4, SW5, and SW6.

Capacitor C smoothes the voltage output from DC power supply PS and input to inverter circuit 2.

The switching elements SW1 to SW6 are, for example, IGBTs (Insulated Gate Bipolar Transistors). The switching element SW1 is the switching element of the upper arm of the U phase. The switching element SW2 is the switching element of the lower arm of the U phase. The switching element SW3 is the switching element of the upper arm of the V phase. The switching element SW4 is the switching element of the lower arm of the V phase. The switching element SW5 is the switching element of the upper arm of the W phase. The switching element SW6 is the switching element of the lower arm of the W phase. One terminal of the capacitor C is connected to the positive terminal of the DC power supply PS and the collector terminals of the switching elements SW1, SW3, and SW5. The other terminal of the capacitor C is connected to the negative terminal of the DC power supply PS and the emitter terminals of the switching elements SW2, SW4, and SW6.

The connection point between the emitter terminal of switching element SW1 and the collector terminal of switching element SW2 is connected to the U-phase input terminal of motor M via current sensor Se1. The connection point between the emitter terminal of switching element SW3 and the collector terminal of switching element SW4 is connected to the V-phase input terminal of motor M via current sensor Se2. The connection point between the emitter terminal of switching element SW5 and the collector terminal of switching element SW6 is connected to the W-phase input terminal of motor M via current sensor Se3.

A drive signal is supplied from the control device 3 to the gates of each of the switching elements SW1 to SW6. Each of the switching elements SW1 to SW6 is turned on or off based on the drive signal supplied to the gate. By turning on or off each of the switching elements SW1 to SW6, the DC power output from the DC power source PS is converted into three AC powers whose phases differ from each other by 120 degrees, and these AC powers are input to the input terminals of the three phases (U phase, V phase, and W phase) of the motor M, causing the rotor of the motor M to rotate.

The current sensors Se1 to Se3 are configured with Hall elements, shunt resistors, or the like. The current sensor Se1 detects a U-phase current value _{Iu, which is the current value of the AC current flowing through the U-phase of the motor M, and outputs it to the control device 3. The current sensor Se2 detects a V-phase current value Iv ,} which is the current value of the AC current flowing through the V-phase of the motor M, and outputs it to the control device 3. The current sensor Se3 detects a W-phase current value _Iw, which is the current value of the AC current flowing through the W-phase of the motor M, and outputs it to the control device 3. In this embodiment, the control system 1 includes three current sensors (current sensors Se1 to Se3), but may include two current sensors.

The control device 3 is a device that performs position sensorless control of the motor M. The control device 3 drives the motor M by controlling the inverter circuit 2. The control device 3 generates a drive signal that controls the inverter circuit 2. The control device 3 includes a drive circuit 4 and a calculator 5.

The drive circuit 4 is configured with an IC (Integrated Circuit) etc. The drive circuit 4 compares the U-phase voltage command value V ^* _u , the V-phase voltage command value V ^* _v , and the W-phase voltage command value V ^* _w output from the calculator 5 with a carrier wave (such as a triangular wave, a sawtooth wave, or an inverse sawtooth wave), and outputs drive signals according to the comparison results to the gate terminals of the switching elements SW1 to SW6.

The calculator 5 is an electronic control unit that is composed of a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). For example, a program stored in the ROM is loaded onto the RAM and executed by the CPU, thereby realizing the various functions of the calculator 5 shown in FIG. 2.

Next, the functional configuration of the calculator 5 will be described with reference to Figures 2 and 3. Figure 2 is a block diagram showing the functional configuration of the calculator shown in Figure 1. Figure 3 is a diagram for explaining the relationship between the d-axis and the γ-axis. As shown in Figure 2, the calculator 5 includes, as functional components, a coordinate conversion unit 51, a γ-δ current command value output unit 52, a γ-δ voltage command value calculation unit 53, a coordinate conversion unit 54, an estimation unit 55, and a detection unit 56.

The coordinate conversion unit 51 converts the U-phase current value _Iu , the V-phase current value _Iv , and the W-phase current value _Iw into a γ-axis current value Iγ and a δ-axis current value _Iδ based on _the estimated position _θ^ re output from the estimation unit 55. That is, the coordinate conversion unit 51 functions as a current value conversion unit that converts the current flowing through the motor M into a γ-axis current value _Iγ and a δ-axis current value _Iδ . The estimated position θ^ _re is an estimate of the position _θre of the rotor of the motor M. The position _θre is also referred to as an electrical angle. This conversion method is well known, so a detailed description will be omitted here.

The coordinate conversion unit 51 outputs the γ-axis current value _Iγ and the δ-axis current value _Iδ to the γ-δ voltage command value calculation unit 53 and the estimation unit 55. The coordinate conversion unit 51 receives current values of two phases out of the U-phase current value _Iu , the V-phase current value _Iv , and the W-phase current value _Iw , and the current value of the remaining phase may be calculated from the input current values of the two phases.

In the notation "θ^ _re ", "^" is located to the upper right of "θ", but "θ^ _re " has the same meaning as the symbol written on the arrow from the estimation unit 55 to the coordinate conversion unit 51 in Fig. 2. The same applies to other notations of "^". In this specification, the symbol "^" means an estimated value.

As shown in FIG. 3, the position θ _re is the angle between the α axis of the α-β coordinate system and the d axis of the d-q coordinate system. The estimated position θ^ _re is the angle between the α axis of the α-β coordinate system and the γ axis of the γ-δ coordinate system. The α-β coordinate system is a fixed coordinate system. The d-q coordinate system is a rotating coordinate system in which the direction of the north pole of the magnet of the motor M is the d axis and the direction perpendicular to the d axis is the q axis. The γ-δ coordinate system is an estimated rotating coordinate system in position sensorless control, in which the axis equivalent to the d axis of the d-q coordinate system is the γ axis and the axis equivalent to the q axis is the δ axis. The γ axis of the γ-δ coordinate system and the d axis of the d-q coordinate system are shifted by a position error Δθ _re .

In other words, the position error Δθ _re is the true value of the angle between the γ-axis in the γ-δ coordinate system and the d-axis in the d-q coordinate system (or the angle between the δ-axis in the γ-δ coordinate system and the q-axis in the d-q coordinate system). The position error Δθ _re is also called the electrical angle error. When the position error Δθ _re is zero, the γ-axis coincides with the d-axis, and the δ-axis coincides with the q-axis.

The γ-δ current command value output unit 52 selectively outputs the specified γ-axis current value I ^* _γ1 (first specified γ-axis current value), the specified δ-axis current value I ^* _δ1 (first specified δ-axis current value), and the specified γ-axis current value I ^* _γ2 (second specified γ-axis current value), and the specified δ-axis current value I ^* _δ2 (second specified δ-axis current value) as the specified γ-axis current value I ^* _γ and the specified δ-axis current value I ^* _δ to the specified γ-δ voltage value calculation unit 53. The specified γ-axis current value I ^* _γ1 and the specified δ-axis current value I ^* _δ1 are current command values calculated based on the specified angular velocity value ω ^* of the motor M. The specified γ-axis current value I ^* _γ2 and the specified δ-axis current value I ^* _δ2 are both current command values of zero amperes. The γ-δ current command value output unit 52 includes a current command value generating unit 52a, a current command value generating unit 52b, and a switching unit 52c.

The current command value generating unit 52a calculates an angular velocity difference Δω between an angular velocity command value ω ^* input from outside and an estimated angular velocity ω^ _re output from an estimation unit 55, and calculates a torque command value T ^* using the angular velocity difference Δω. The estimated angular velocity ω^ _re is an estimated value of the angular velocity _ωre of the rotor of the motor M. The current command value generating unit 52a calculates a γ-axis current command value I ^* _γ1 and a δ-axis current command value I ^* _δ1 using the torque command value T ^* . Note that a method for generating the γ-axis current command value I ^* _γ1 and the δ-axis current command value I ^* _δ1 is publicly known, and therefore a detailed description thereof will be omitted here. The current command value generating unit 52a outputs the γ-axis current command value I ^* _γ1 and the δ-axis current command value I ^* _δ1 to the switching unit 52c.

The current command value generating unit 52b generates a γ-axis current command value I ^* _γ2 of zero amperes and a δ-axis current command value I ^* _δ2 of zero amperes, and outputs the γ-axis current command value I ^* _γ2 and the δ-axis current command value I ^* _δ2 to the switching unit 52c.

The switching unit 52c selects one of the sets of the specified γ-axis current value I ^* _γ1 and the specified δ-axis current value I ^* _δ1 output from the current command value generating unit 52a and the specified γ-axis current value I ^* _γ2 and the specified δ-axis current value I ^* _δ2 output from the current command value generating unit 52b, and outputs the set as the specified γ-axis current value I ^* _γ and the specified δ-axis current value I ^* _δ . For example, while receiving a detection command, the switching unit 52c selects the specified γ-axis current value I ^* _γ2 and the specified δ-axis current value I ^* _δ2 , and outputs the specified γ-axis current value I ^* _γ2 and the specified δ-axis current value I ^* _δ2 as the specified γ-axis current value I ^* _γ and the specified δ-axis current value I ^* _δ . When no detection command is received, the switching unit 52c selects the specified γ-axis current value I ^* _γ1 and the specified δ-axis current value I ^* _δ1 , and outputs the specified γ-axis current value I ^* _γ1 and the specified δ-axis current value I ^* _δ1 as the specified γ-axis current value I ^* _γ and the specified δ-axis current value I ^* _δ .

The detection command is output at any timing for a predetermined period. The detection command may be output at a predetermined cycle. The predetermined period is set to, for example, a time longer than a convergence time from when the specified γ-axis current value I ^* _γ2 and the specified δ-axis current value I ^* _δ2 are output until the γ-axis current value _Iγ and the δ-axis current value _Iδ converge to zero amperes.

The γ-δ voltage command value calculation unit 53 generates a γ-axis voltage command value V ^* _γ and a δ-axis voltage command value V ^* _δ . For example, the γ-δ voltage command value calculation unit 53 calculates a differential γ-axis current command value ΔI ^* _γ which is the difference between the γ-axis current command value I* _γ and the γ-axis current value _Iγ , and calculates a differential δ-axis current command value ^{ΔI *} _δ which is the difference between the δ-axis current command value I* _δ and the δ-axis current value _Iδ , and converts the differential γ-axis current command value ΔI ^* _γ and the differential δ-axis current command value ΔI ^* _δ into the γ-axis voltage command value V ^* _γ and the ^δ -axis voltage command value V ^* _δ .

That is, the γ-δ voltage command value calculation unit 53 calculates a γ-axis voltage command value V ^* _γ based on the γ-axis current command value I ^* _γ and the γ-axis current value _Iγ , and calculates a δ-axis voltage command value V ^* _δ based on the δ-axis current command value I ^* _δ and _the δ-axis current value Iδ. The method of generating the γ-axis voltage command value V ^* _γ and the δ-axis voltage command value V ^* _δ is publicly known, so a detailed description will be omitted here. The γ-δ voltage command value calculation unit 53 outputs the γ-axis voltage command value V ^* _γ and the δ-axis voltage command value V ^* _δ to the coordinate conversion unit 54, the estimation unit 55, and the detection unit 56.

The coordinate conversion unit 54 _converts the γ-axis voltage command value V ^* _γ and the δ-axis voltage command value V ^* _δ into a U-phase voltage command value V ^* _u , a V-phase voltage command value V ^* _v , and a W-phase voltage command value V* _w based on the estimated position θ ^{^} re output from the estimation unit 55. This conversion method is well known, so a detailed description will be omitted here. The coordinate conversion unit 54 outputs the U-phase voltage command value V ^* _u , the V-phase voltage command value V ^* _v , and the W-phase voltage command value V ^* _w to the drive circuit 4. In other words, the coordinate conversion unit 54 and the drive circuit 4 function as a drive signal output unit that converts the γ-axis voltage command value V ^* _γ and the δ-axis voltage command value V ^* _δ into drive signals.

The estimator 55 calculates an estimated angular velocity ω^ _re and an estimated position θ^ _re . The estimator 55 calculates an estimated extended electromotive force (EEMF) e generated in the motor M, which is an estimated extended electromotive force e, based on the γ-axis current value _Iγ , the δ-axis current value _Iδ , and estimated motor parameters that can be estimated in advance, and calculates an estimated position θ^ _re based on the estimated extended electromotive force e.

For example, the estimation unit 55 calculates an estimated position error Δθ^ _re from the estimated extended induced voltage e^, and multiplies the estimated position error Δθ^ _re by a predetermined transfer function to obtain an estimated angular velocity ω^ _re . The estimated position error Δθ^ _re is an estimated value of the position error Δθ^ _re . The estimation unit 55 then calculates an estimated position θ^ _re based on the estimated angular velocity ω^ _re and the estimated position error Δθ^ _re . The estimation unit 55 outputs the estimated position θ^ _re to the coordinate conversion units 51 and 54, and outputs the estimated angular velocity ω^ _re to the γ-δ current command value output unit 52.

The detector 56 detects the loss of synchronism of the motor M based on the estimated position error Δθ^ _re . Here, the extended induced voltage model (γ-axis voltage value V _γ and δ-axis voltage value V _δ ) on the γ-δ coordinate system is expressed by the formulas (1) and (2) using the γ-axis current value I _γ , the δ-axis current value I _δ , the d-axis current value I _d , the q-axis current value I _q , the angular velocity ω _re , the position error Δθ _re and the motor parameters. Note that p represents the time differential operator d/dt. The winding resistance R, the d-axis inductance L _d , the q-axis inductance L _q and the induced voltage constant K _E are the motor parameters of the motor M to be controlled. The element with a dot on the position error Δθ _re represents the differential value of the position error Δθ _re . The element with a dot on the q-axis current value I _q represents the differential value of the q-axis current value I _q .

When both the γ-axis current value _Iγ and the δ-axis current value _Iδ converge to zero amperes, the formula (3) is obtained by setting the γ-axis current value _Iγ and the δ-axis current value _Iδ to zero in the formula (1). Similarly, the formula (4) is obtained by setting the γ-axis current value _Iγ and the δ-axis current value _Iδ to zero in the formula (2).

By transforming the equation for deriving the position error Δθ _re using equations (3) and (4), equation (5) is obtained.

In equation (5), by substituting the specified γ-axis voltage value _V*γ and the specified δ-axis voltage value V ^* _δ instead of the γ-axis voltage value _Vγ and _{the δ-axis voltage value Vδ} ^, respectively, equation (6) for deriving the estimated position error Δθ^ _re can be obtained.

The detection unit 56 calculates the estimated position error Δθ^ _re by using the formula (6). That is, the detection unit 56 calculates the estimated position error Δθ^re based on the γ-axis voltage command value V ^* _γ and the δ-axis voltage command value V ^* _δ when the γ-δ current command value I ^* _γ2 and the δ-axis current command value I ^* _δ2 are output as the γ-axis current command value I ^* _γ and the δ-axis current command value I ^* _δ in the γ-δ current command value output unit 52. The detection unit 56 calculates the estimated position error Δθ^ _re in response to the lapse of the convergence time after the γ-axis current command value I ^* _γ2 and the δ-axis current command value I ^* _δ2 are _output , for example.

Then, the detection unit 56 detects out-of-step of the motor M based on the estimated position error Δθ^ _re . Specifically, the detection unit 56 compares the estimated position error Δθ^ _re with a predetermined threshold, and determines that out-of-step of the motor M has occurred when the estimated position error Δθ^ _re is greater than the threshold, and determines that out-of-step of the motor M has not occurred when the estimated position error Δθ^ _re is equal to or smaller than the threshold. For example, π/2 (rad) is used as the threshold. Note that when it is determined that out-of-step of the motor M has occurred, the motor M may be stopped.

In the control device 3 described above, when the specified γ-axis current value I ^* _γ2 and the specified δ-axis current value I ^* _δ2 are output as the specified γ-axis current value I ^* _γ and the specified δ-axis current value I ^* _δ , the estimated position error Δθ^ _re is calculated based on the specified γ-axis voltage value V ^* _γ and the specified δ-axis voltage value V ^* _δ . Since the specified γ-axis current value I ^* _γ2 and the specified δ-axis current value I ^* _δ2 are current command values of zero amperes, when the specified γ-axis current value I ^* _γ2 and the specified δ-axis current value I ^* _δ2 are output as the specified γ-axis current value I ^* _γ and the specified δ-axis current value I ^* _δ , the specified γ-axis current value _Iγ and the specified δ-axis current value _Iδ converge to zero amperes. In this state, the extended induced voltage model on the γ-δ coordinate system becomes an equation that is independent of the motor parameters (winding resistance R, d-axis inductance L _d , and q-axis inductance L _q ) and the estimated angular velocity ω ^*, as shown in equations (3) and (4).

In the control device 3, the estimated position error Δθ^ _re is calculated using the extended induced voltage model shown in equations (3) and (4). Therefore, even if an error occurs in the motor parameters or the angular velocity command value ω ^* , the estimated position error Δθ^ _re is not affected by it. Since out-of-step of the motor M is detected based on the estimated position error Δθ^ _re calculated as described above, it is possible to prevent errors in the motor parameters and the angular velocity command value ω ^* from affecting the accuracy of out-of-step detection. Therefore, it is possible to improve the accuracy of out-of-step detection in position sensorless control.

One embodiment of the present disclosure has been described in detail above, but the control device according to the present disclosure is not limited to the above embodiment.

In the above embodiment, the detection unit 56 calculates the estimated position error Δθ^ _re using equation (6) and detects out-of-step of the motor M based on the estimated position error Δθ^ _re . Instead of this configuration, a configuration may be adopted in which the estimator 55 calculates the estimated position error Δθ^ _re using equation (6) and the detection unit 56 detects out-of-step of the motor M based on the estimated position error Δθ^ _re calculated by the estimator 55.

2... inverter circuit (inverter), 3... control device, 4... drive circuit (drive signal output section), 51... coordinate conversion section (current value conversion section), 52... gamma-delta current command value output section, 53... gamma-delta voltage command value calculation section, 54... coordinate conversion section (drive signal output section), 55... estimation section, 56... detection section, M... motor.

Claims (1)

A control device that generates a drive signal to control an inverter that drives a motor,
a current value converter for converting a current flowing through the motor into a γ-axis current value and a δ-axis current value;
a γ-δ current command value output unit that selectively outputs, as the specified γ-axis current value and the specified δ-axis current value, a first specified γ-axis current value and a first specified δ-axis current value calculated based on the specified angular velocity value of the motor, and a second specified γ-axis current value and a second specified δ-axis current value of zero amperes;
a γ-δ voltage command value calculation unit that calculates a γ-axis voltage command value based on the γ-axis current value and the γ-axis current command value, and calculates a δ-axis voltage command value based on the δ-axis current value and the δ-axis current command value;
a drive signal output unit that converts the γ-axis voltage command value and the δ-axis voltage command value into the drive signals;
a detection unit that detects out-of-step of the motor based on an estimated position error, which is an estimated value of a position error between a γ-axis in a γ-δ coordinate system and a d-axis in a d-q coordinate system, and is calculated based on the specified γ-axis voltage value and the specified δ-axis voltage value when the specified second γ-axis current value and the specified second δ-axis current value are output as the specified γ-axis current value and the specified δ-axis current value;
A control device comprising:

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