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 at least one 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 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) inverter, wherein the method comprises: a) Measuring a phase voltage at the common phase of the operated three-phase motor (M1) and at least one single-phase motor (M2, M3) to obtain an actual voltage; b) Comparing the actual voltage with a target voltage; and c) Regulating or controlling the actual voltage to the target voltage. 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 at least one single-strand motor (M2, M3) of an electrical household appliance according to the method, as well as 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 convergence rate to steady-state 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 6, and an electrical household appliance having the features of patent claim 10. 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 a coupling between the three-phase motor and the single-phase motor is eliminated or at least reduced.

[0009] The invention is based on the following basic idea: When the single-phase motor and the three-phase motor are operated by a three-phase inverter, a total current of both motors flows through the second phase when the three-phase motor is powered by the first phase and the second phase of the three-phase inverter, and the single-phase motor is powered by the second phase and the third phase of the three-phase inverter. However, the inverter cannot be considered 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 interference 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 the single-phase motor, and on the other hand, the current flowing through the 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 measuring the phase voltage on the common phase. This yields the actual voltage, which is then compared with the target voltage and then regulated or controlled to this value. The target voltage is stored in the inverter.

[0010] The invention relates to a method for simultaneously controlling a three-phase motor in a 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, the method comprising: a) measuring a phase voltage on the common second phase of the operated three-phase motor and the at least one single-phase motor to obtain an actual voltage; b) comparing the actual voltage with a target voltage; and c) Regulating or controlling the actual voltage to the target voltage.

[0011] In a preferred embodiment, step a) is performed using a voltage divider and capacitive smoothing. The voltage divider reduces the voltage to be measured to a value that can be read by a control device of the converter. The capacitive smoothing serves to smooth the clocked voltages, preferably PWM (pulse width modulation) voltages. The voltage divider is preferably a series circuit of two resistors.

[0012] The converter preferably generates pseudo-sine signals using pulse-width modulation. A cutoff frequency of the voltage divider is preferably lower than the PWM frequency. This ensures that voltage ripple is sufficiently low. The cutoff frequency of the voltage divider is preferably higher than a predetermined cutoff frequency threshold. The predetermined cutoff frequency threshold is preferably selected such that the cutoff frequency is high enough to enable rapid readjustment or control of the voltage.

[0013] Preferably, closed-loop control is performed in step c). Alternatively, open-loop control is preferably performed in step c). In a preferred embodiment, a difference obtained from step b) is applied as a feedforward control.

[0014] 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.

[0015] In a preferred embodiment, the converter comprises a control or regulating device. The control or regulating device preferably comprises a PI controller, P controller, I controller, PD controller, PID controller, state controller, or fuzzy controller, or a controller.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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 a hot-air blower motor. The electrical household appliance can also have multiple single-phase motors, each of which can be controlled individually and 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 controller then contains, for example, a relay for switching between the two single-phase motors.

[0020] 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 another partial circuit diagram of the Fig. 1 shown engine control; Fig. 3 a partial circuit diagram of the Fig. 1 shown engine control; Fig. 4 a partial circuit diagram of a variant of the Fig. 3 shown engine control; Fig. 5 a flow diagram of a method according to the invention; and Fig. 6 a voltage error curve.

[0021] Fig. Figure 1 shows a circuit diagram of a motor controller according to the invention. The motor controller includes the converter with a B6 bridge. The B6 bridge includes a first half-bridge 12 and a second half-bridge 13, which together form a first H-bridge 15. The first half-bridge 12 includes a first transistor T1, a second transistor T2, a first diode D1, a second diode D2, and a first measuring resistor R1 as the first shunt.

[0022] The second half-bridge 13 comprises 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 comprises 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 system 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 system has two single-phase motors M2, M3, it has a relay Rel1 and another relay Rel2. The relay Rel2 does not need to be present in the motor control system 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 relay 1, a phase W between the single-strand motor M1 and the motor control system is disconnected. 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 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 controller is operated via a voltage input 10 with an AC voltage. 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. 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 three-phase motor M1 is assigned to the two half-bridges 12, 13 and can be operated by the first H-bridge 15. For this purpose, the converter has a control or regulating device 17 connected to the four transistors T1-T4. 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 a second H-bridge 16 on the control or regulating device 17. For this purpose, the control or regulating device 17 is connected to the four transistors T4-T6. 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 controlled 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. 5 and described below.

[0028] Fig. 2 shows a partial circuit diagram of the Fig. 1 shown engine control. The Fig. The engine control shown in Figure 2 corresponds to the one in Fig. 1, wherein, for the sake of clarity, only the control or regulating device 17 is shown, which is further connected to a voltage divider 18 and a smoothing capacitor 19. The voltage divider 18 has two series-connected resistors 18a, 18b.

[0029] Fig. 3 shows another partial circuit diagram of the Fig. 1. Shown is a portion of the control or regulating device 17, which has a comparison unit 22 and a controller 20. The comparison unit 22 is configured to compare the actual voltage with a target voltage stored in the computer 17. The controller 20 is configured to adjust the voltage at the converter phase based on the comparison such that the actual voltage is regulated to the target voltage.

[0030] Fig. 4 shows a partial circuit diagram of a variant of the Fig. 3 shown engine control. The Fig. 4 shown engine control corresponds to the one in Fig. 3 with the difference that instead of the regulator it has a controller 21 which is designed to adjust the current supply to the simultaneously operated motors on the basis of the comparison in such a way that the actual voltage is controlled to the target voltage.

[0031] Fig. Figure 5 shows a flowchart of a method according to the invention. The method is for simultaneously controlling the three-phase motor M1 in two-phase operation and the single-phase motors M2 and M3 of an electrical household appliance by means of the Fig. 1. The method comprises the following steps: a) measuring a phase voltage on the common second phase of the operated three-phase and at least one single-phase motor M1, M2 or M3 to obtain an actual voltage; b) comparing the actual voltage with a target voltage; and c) regulating or controlling the actual voltage to the target voltage. Step a) can be carried out using a voltage divider and capacitive smoothing if the motor control system has the Fig. 2 shown voltage divider and smoothing capacitor. Steps b) and c) can be carried out using the Fig. 3 shown comparison unit and controller or the one in Fig. 4 shown comparison unit and control.

[0032] Fig. Figure 6 shows an example of the voltage error curve for a converter phase. In an ideal converter, the voltage at the output would be exactly the same as the one intended. However, in a real converter, 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.

[0033] 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 a trade fairs b Compare c Taxes or rules 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 Control unit; computer 18 voltage dividers 18a,b each resistance 19 Smoothing capacitor 20 controllers 21 Control 22 Comparison unit

Claims

[1] Method for the simultaneous control of a three-phase motor (M1) in a 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: a) measuring a phase voltage at the common second phase of the operated three-phase motor (M1) and at least one single-phase motor (M2, M3) to obtain an actual voltage; b) comparing the actual voltage with a target voltage; and c) Regulating or controlling the actual voltage to the target voltage. [2] Method according to claim 1, characterized bythat step a) is carried out using a voltage divider and capacitive smoothing. [3] Method according to one of the preceding claims, characterized by that the converter generates pseudo-sine signals using pulse width modulation. [4] Method according to claim 2, characterized by that a cutoff frequency of the voltage divider with capacitive smoothing is smaller than a PWM frequency and larger than a predetermined cutoff frequency threshold. [5] Method according to one of the preceding claims, characterized by that a difference obtained from step b) is applied as feedforward control. [6] 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. [7] Engine control according to claim 6, characterized by that the converter has a control or regulating device (17), which preferably has a PI controller, P controller, I controller, PD controller, PID controller, state controller or fuzzy controller or a controller. [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 6 or 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 and / or the one further single-strand motor (M3) is a motor of a hot air blower.

Images