Method for simultaneously controlling a three-phase motor in two-phase operation and a single-phase motor, motor control and electrical household appliance

Abstract

The invention relates to a method for simultaneously controlling a three-phase motor (M1) in two-phase operation and a single-phase motor (M2, M3) of an electrical household appliance by means of a three-phase (U, V, W) inverter, such that the three-phase motor (M1) is energized by means of a first phase (U) and a second phase (V) of the three-phase (U, V, W) inverter and the single-phase motor (M2, M3) is energized by means of the second phase (V) and a third phase (W) of the three-phase (U, V, W) inverter, wherein the method comprises: compensating a voltage error by applying an inverse voltage error curve which is inverse to a determined voltage error curve, wherein the determined voltage error curve is stored in the control device (17) or is determined before the compensation.Furthermore, the invention relates to a motor control unit comprising the inverter configured to control the three-strand motor (M1) in two-phase operation and the single-strand motor (M2, M3) of an electrical household appliance according to the method, and to an electrical household appliance comprising the motor control unit.

Description

[0001] The invention relates to a method for simultaneously controlling a three-phase motor in two-phase operation and a single-phase motor, a motor controller, and an electrical household appliance. In particular, the invention relates to a method for simultaneously controlling a three-phase motor in two-phase operation and a single-phase motor of an electrical household appliance by means of a three-phase converter such that the three-phase motor is energized by means of a first phase and a second phase of the three-phase converter, and the single-phase motor is energized by means of the second phase and a third phase of the three-phase converter. The invention also relates to a motor controller comprising the converter configured to carry out the method, and to an electrical household appliance containing the motor controller.

[0002] DE 10 2021 132 938 A1 describes the simultaneous, controlled operation of two single-phase motors on a three-phase B6 converter at variable and even different speeds. However, it is desirable to control a three-phase and a single-phase motor simultaneously.

[0003] In the article "Robust Tracking Control of a Three-Phase DC-AC Inverter for UPS Application under Unbalanced Load Conditions" by Chivon Choeung et al., a robust control technique for a three-phase uninterruptible power supply (UPS) with an LC output filter under unbalanced load conditions is described. The proposed control scheme consists of a combination of two robust controllers for the positive and negative sequence components to generate balanced sinusoidal output voltages by eliminating the negative sequence component caused by unbalanced loads. The controller gains are determined by a linear matrix inequality (LMI)-based optimization to maximize the steady-state convergence rate in the presence of uncertainties in the LC filter.

[0004] EP 0 208 088 A1 relates to a device for generating a symmetrical output voltage system at the output of a transformer TR with a loadable secondary star point N or a star point former, even with an asymmetrical load. For this purpose, each primary-side terminal A', B', C' is fed by a bridge-arm pair WA, WB, WC of a pulse-controlled inverter. In a decoupling network E, the line voltages UL1, UL2, UL3 measured on the secondary side are converted into equivalent actual values ​​according to the structure of the transformer circuit TR. These equivalent actual values, for symmetrical output voltages, represent a likewise symmetrical system UA, UB, UC with a free star point. These equivalent actual values ​​are regulated to a system of symmetrical setpoints UA*, UB*, UC*.

[0005] CN 2 01 797 450 U relates to a dual boost inversion pre-stage high-frequency link matrix three-phase four-leg converter comprising a dual boost high-frequency inverter circuit 1, a high-frequency link transformer 2, a matrix three-phase four-leg converter 3, and a system output link 4. The dual boost circuit realizes amplitude modulation boost high-frequency inversion; the high-frequency transformer is used for electrical isolation and power transmission; the matrix three-phase four-leg converter realizes symmetrical and balanced AC output under unbalanced load; and the system output link is connected to an electrical device.The three-phase four-leg converter with dual boost-inversion pre-stage and high-frequency link matrix has the advantage of solving the problem of unbalanced load simultaneously by means of high-frequency isolation conversion, boost inversion and three-phase four-leg power conversion.

[0006] The invention therefore addresses the problem of providing a method, a motor control and an electrical household appliance in which a simultaneous control of a three-phase motor in a two-phase operation and a single-phase motor of an electrical household appliance is provided by means of a three-phase converter without coupling or with at least reduced coupling between the three-phase and the single-phase motor.

[0007] According to the invention, this problem is solved by a method having the features of patent claim 1, a motor control having the features of patent claim 7, and an electrical household appliance having the features of patent claim 8. Advantageous embodiments and further developments of the invention emerge from the following subclaims.

[0008] The advantages achievable with the invention are that a voltage error is eliminated or at least reduced, and the coupling between the three-phase motor and the at least one single-phase motor is eliminated or at least reduced. No additional hardware is required to implement the decoupling. Only minimal computing power and memory space are required in a control or regulating device. This makes the solution hardware- and cost-neutral.

[0009] The invention is based on the following basic idea: When the at least one single-phase motor and the three-phase motor are operated by means of the three-phase inverter, a total current of both motors flows via the second phase when the three-phase motor is energized by the first phase and the second phase of the three-phase inverter and the at least one single-phase motor is energized by the second phase and the third phase of the three-phase inverter. However, the inverter cannot be regarded as an ideal voltage source, so the two motors are not completely decoupled from each other. Coupling exists because the inverter has a current-dependent voltage error on each phase. This causes mutual influence from the respective phase currents.The influence is not only unidirectional: on the one hand, the current flowing through the three-phase motor influences the current flowing through at least one single-phase motor, and on the other hand, the current flowing through at least one single-phase motor influences the current flowing through the three-phase motor. Here, it is fundamentally assumed that this mutual influence is due to the voltage errors of the converter. With an ideal converter, the voltage at the output would be exactly the same as that which is intended to be output. With a real converter, however, the setpoint and actual voltage values ​​differ from one another. The voltage error therefore depends heavily on the current. If the current flows from the converter towards the motor, the actual voltage is lower than the setpoint voltage. If the current flows from the motor towards the converter, the actual voltage is higher than the setpoint voltage.If two motors are operated on the same inverter phase, the voltage error results from the sum of the two currents. This results in mutual interference. The method according to the invention is based on the fundamental idea of ​​eliminating the mutual interference of the motor currents by compensating for the voltage error by applying an inverse voltage error curve that is the inverse of a determined voltage error curve.

[0010] The invention relates to a method for simultaneously controlling a three-phase motor in two-phase operation and at least one single-phase motor of an electrical household appliance by means of a three-phase converter such that the three-phase motor is energized by means of a first phase and a second phase of the three-phase converter and the at least one single-phase motor is energized by means of the second phase and a third phase of the three-phase converter, wherein the method comprises: compensating for a voltage error by applying an inverse voltage error curve which is inverse to a determined voltage error curve, wherein the determined voltage error curve is stored in the converter or is determined before the compensation.

[0011] In a preferred embodiment, the compensation is performed on the second phase. This compensates for the voltage error so that the actual voltage equals the target voltage. The at least one single-phase motor and the three-phase motor are decoupled in the common phase.

[0012] Alternatively, or additionally, compensation is performed on a phase other than the second phase. While this does not further decouple the current, it does reduce harmonics in the current and improves the control characteristics.

[0013] In a preferred embodiment, the inverse voltage error curve is and / or will be stored in the control device (17) as a look-up table. This eliminates the need to determine the voltage error curve prior to compensation.

[0014] Alternatively or additionally, the inverse voltage error curve is preferably and / or is represented by an approximation of a function. This can be, for example, an e-function, which can optionally be supplemented by a straight line.

[0015] In a preferred embodiment, the converter generates pseudo-sine signals by means of pulse width modulation.

[0016] The invention further relates to a motor control system comprising a converter designed to simultaneously control a three-phase motor in two-phase operation and at least one single-phase motor of an electrical household appliance according to a method according to one or more of the previously described embodiments.

[0017] The converter preferably has a B6 bridge. It preferably has a first H-bridge configured to operate the three-phase motor and a second H-bridge configured to operate the single-phase motor. The first H-bridge preferably has a first half-bridge and a second half-bridge. The second H-bridge preferably has the second half-bridge and a third half-bridge. The three-phase motor and the single-phase motor can therefore be operated jointly via the second half-bridge.

[0018] The invention further relates to an electrical household appliance having a three-phase motor and at least one single-phase motor and the motor control according to one or more of the previously described embodiments.

[0019] The electrical household appliance is preferably designed as a water-conducting electrical household appliance. More preferably, the electrical household appliance is designed as a dishwasher, disinfectant, washing machine, washer-dryer, or dryer. The electrical household appliance is particularly preferably a dishwasher.

[0020] In a preferred embodiment, the three-phase motor is a circulation pump motor. Preferably, the at least one single-phase motor is a drain pump motor, or the one further motor is a hot-air blower motor. The electrical household appliance can also have multiple single-phase motors, each of which can be individually controlled simultaneously with the three-phase motor. For example, it has two single-phase motors, one of which is a drain pump motor and the other of which is a hot-air blower motor. The motor control then contains, for example, a relay for switching between the two single-phase motors.

[0021] An embodiment of the invention is shown schematically in the drawings and is described in more detail below. It shows schematically and not to scale. Fig. 1 is a circuit diagram of an engine control system according to the invention; Fig. 2 a flowchart of a method according to the invention; Fig. 3 a partial circuit diagram of the Fig. 1 shown engine control; Fig. 4 another partial circuit diagram of the Fig. 1 shown engine control; and Fig. 5 a voltage error curve.

[0022] Fig. 1 shows a circuit diagram of a motor controller according to the invention. The motor controller has the converter with a B6 bridge. The B6 bridge has a first half-bridge 12 and a second half-bridge 13, which together form a first H-bridge 15. The first half-bridge 12 has a first transistor T1, a second transistor T2, a first diode D1, a second diode D2 and a first measuring resistor R1 as a first shunt. The second half-bridge 13 has a third transistor T3, a fourth transistor T4, a third diode D3, a fourth diode D4 and a second measuring resistor R2 as a second shunt. The second half-bridge 13 and a third half-bridge 14 form a second H-bridge 16. The third half-bridge has a fifth transistor T5, a sixth transistor T6, a fifth diode D5, a sixth diode D6 and a third measuring resistor R3 as a third shunt.

[0023] The motor control is described for the simultaneous control of a three-phase motor M1 in two-phase operation and a single-phase motor – here purely as an example, two single-phase motors M2, M3. However, it can also be designed to control only a single-phase motor. If the motor control has two single-phase motors M2, M3, it has a relay Rel1 and another relay Rel2. These relays do not need to be present in the motor control if it only has one of the two single-phase motors M2, M3. The three-phase motor M1 is energized or supplied with current i via a first phase U and a second phase V of the three-phase U, V, W converter. u , i v and the single-phase motor M2, M3 is supplied with current i by means of the second phase V and a third phase W by means of the three-phase U, V, W inverter. v , i w supplied.

[0024] Using Rel1, a phase W between the single-strand motor M1 and the motor control system is separated. Instead, one of the two single-strand motors M2 or M3 is switched on. The additional relay Rel2 can be used to switch between the single-strand motor M2 and the single-strand motor M3. The motors M1, M2 or M3 are connected together on a phase V. When relay Rel1 is switched, motor M1 continues to run in two-phase mode on phase U and phase V. If one of the single-strand motors M2 or M3 is now energized on phase W and phase V, the total current of both motors M1, M2 or M3 flows via phase V. It is irrelevant whether the three-strand motor M1 is operated in parallel with the single-strand motor M2 or the single-strand motor M3.

[0025] The motor control is operated via a voltage input 10 with an AC voltage, in which the AC voltage of the voltage input 10 is converted into a DC voltage via a rectifier 11 and then smoothed using a smoothing capacitor (not shown). The smoothed DC voltage is then applied as an intermediate circuit voltage in parallel to the first half-bridge 12 and the second half-bridge 13, which together form the first H-bridge 15. The two half-bridges 12, 13 are assigned the three-phase motor M1, which can be operated by the first H-bridge 15. For this purpose, the converter has a control or regulating device 17, which is connected to the four transistors T1-T4 via the diodes D1, D2, D3, D4.The two measuring resistors R1, R2 are also connected to the control or regulating device 17, so that the currents in the three-phase motor M1 are recorded during operation, and the three-phase motor M1 can be operated in a controlled manner by the control or regulating device 17 based on this. The single-phase motors M2, M3 are operated by the control or regulating device 17 using a second H-bridge 16. For this purpose, the control or regulating device 17 is connected to the four transistors T4-T6 via the diodes D3, D4, D5, and D6. The two measuring resistors R2, R3 are also connected to the control or regulating device 17. Accordingly, the single-phase motors M2, M3 can be operated in a controlled manner by the control or regulating device 17 based on the currents during operation.

[0026] The second half-bridge 13 can thus be used either by the first H-bridge 15 to operate the three-phase motor M1 or by the second H-bridge 16 to operate the single-phase motors M2, M3. On the other hand, the second half-bridge 13 can also be used or operated simultaneously as a component of both H-bridges 15, 16 to operate motors M1, M2, and M3 simultaneously and thus in parallel.

[0027] To decouple the motors M1 and M2 or M3 during simultaneous operation, the Fig. 2 and described below.

[0028] Fig. Figure 2 shows a flowchart of a method according to the invention. The method comprises a step 21 for compensating a voltage error by applying an inverse voltage error curve that is inverse to a determined voltage error curve. The determined voltage error curve can be stored in the control device (17). Alternatively, an optional step 20 for determining the voltage error curve is performed before step 21.

[0029] Fig. 3 shows a partial circuit diagram of the Fig. 1. The control or regulation device 17 has a control 18. Furthermore, an inverse voltage error curve 22 is stored therein. Alternatively, this can be determined based on the target voltages U, V, W. The voltage error (23) caused by the inverter 19 is compensated by applying the inverse voltage error curve (22) to the common phase V. As a result, the actual voltage approximately corresponds to the target voltage.

[0030] Fig. 4 shows another partial circuit diagram of the Fig. 1 shown engine control. The Fig. 4 shown partial circuit diagram corresponds to the one in Fig. 3 with the difference that the compensation of the voltage error is carried out by applying the inverse voltage error curve 22, which is inverse to the voltage error curve 23, to each of the phases U, V; W.

[0031] Fig. Figure 5 shows an example of the voltage error curve at one inverter phase. In an ideal inverter, the voltage at the output would be exactly the same as the one intended. However, in a real inverter, the setpoint and actual voltage values ​​differ. The voltage error depends heavily on the current. Fig. Figure 6 shows a possible progression of such a voltage error. The voltage error shown in this figure has the following effects: - When the current flows from the inverter towards the motor, the actual voltage is lower than the setpoint voltage. - If the current flows from the motor towards the inverter, the actual voltage is higher than the setpoint voltage.

[0032] If two motors are operated on the same inverter phase, the voltage error results from the corresponding sum of the two currents. This results in mutual interference. List of reference symbols D1-D6 diode i u current flowing in the first phase i v current flowing in the second phase i w current flowing in the third phase M1 three-phase engine M2, M3 each single-strand motor R1-R3 measuring resistors; Shunts Rel1, Rel2 Relay T1-T6 transistors U first phase V second phase W third phase 10 Voltage input 11 rectifiers 12 first half bridge 13 second half bridge 14 third half bridge 15 first H-bridge 16 second H-bridge 17 Regulating or control device 18 Regulation 19 inverters 20 Determine 21 Compensate 23 Inverter voltage error curve 22 inverse voltage error curve

Claims

[1] Method for the simultaneous control of a three-phase motor (M1) in two-phase operation and at least one single-phase motor (M2, M3) of an electrical household appliance by means of a three-phase (U, V, W) converter such that the three-phase motor (M1) is energized by means of a first phase (U) and a second phase (V) of the three-phase (U, V, W) converter and the at least one single-phase motor (M2, M3) is energized by means of the second phase (V) and a third phase (W) of the three-phase (U, V, W) converter, the method comprising: compensating (21) a voltage error by applying an inverse voltage error curve (22) which is inverse to the voltage error curve (23) of the inverter, the determined inverse voltage error curve (22) being stored in the regulating or control device (17) or being determined before the compensation becomes. [2] Method according to claim 1, characterized bythat the compensation is carried out on the second phase. [3] Method according to claim 1, characterized by that compensation is performed on a phase other than a second phase. [4] Method according to one of the preceding claims, characterized by that the inverse voltage error curve (22) is and / or will be stored in the control device (17) as a look-up table. [5] Method according to one of the preceding claims, characterized by that the inverse voltage error curve (22) is and / or is represented by approximating a function. [6] Method according to one of the preceding claims, characterized by that the converter generates pseudo-sine signals using pulse width modulation. [7] Motor control, comprising a converter which is designed to simultaneously control a three-phase motor (M1) in a two-phase operation and at least one single-phase motor (M2, M3) of an electrical household appliance according to a method according to one of the preceding claims. [8] Electrical household appliance, comprising a three-phase motor (M1) and at least one single-phase motor (M2, M3) and the motor control according to claim 7. [9] Electrical household appliance according to claim 8, characterized by that it is designed as a dishwasher, disinfector, washing machine, washer-dryer or dryer. [10] Electrical household appliance according to claim 8 or 9, characterized by that the three-strand motor (M1) is a motor of a circulation pump and the at least one single-strand motor (M2) is a motor of a drain pump (M2) and / or the further single-strand motor (M3) is a motor of a hot air blower (M3).

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