Four-quadrant operation washing machine variable frequency driver

Abstract

The invention discloses a four-quadrant operation washing machine variable frequency driver which comprises a full-bridge booster circuit composed of a PFC power switch tube and a bus capacitor, the full-bridge booster circuit is further connected with an alternating current input voltage source, a high-frequency PFC inductor, a current sampling resistor, a motor driving power switch tube and a controlled motor equivalent model, and the full-bridge booster circuit, the high-frequency PFC inductor, the current sampling resistor, the motor driving power switch tube and the controlled motor equivalent model jointly form a complete circuit. Through the arrangement of the full-bridge booster circuit composed of the four PFC power switch tubes and the bus capacitor, a traditional diode rectifier bridge circuit is replaced, bidirectional flow of energy is successfully achieved, that is, the energy is fed back from the power grid side to the controlled motor equivalent model and from the controlled motor equivalent model to the power grid side, energy waste is avoided, and the energy efficiency is improved. Due to the fact that the washing machine can maintain a high speed reduction rate under the condition that the loss probability of electronic devices is not additionally increased, the operation efficiency of the washing machine is greatly improved, the structural design is exquisite and efficient, and the washing machine has great application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of washing machines, and in particular to a four-quadrant operating washing machine variable frequency driver. Background Art

[0002] As we all know, the working modes of a washing machine include acceleration, constant speed and deceleration. When the washing machine is running at an accelerated speed or a constant speed, the energy required by the system flows from the power grid to the controlled washing machine motor. However, when the washing machine is in the deceleration working mode, the actual energy needs to flow from the motor side to the power grid side, thereby releasing the excess rotational mechanical energy.

[0003] At present, due to the determination of traditional circuit topology, energy flows from the input power grid to the load motor, and energy cannot flow back to the power grid from the motor side. Therefore, when the washing machine is running at a reduced speed, the excess rotational mechanical energy can only be released slowly by increasing motor losses or through the washing machine's own mechanical friction.

[0004] However, this deceleration energy release method leads to energy waste and reduced energy utilization efficiency. In addition, the deceleration rate cannot be controlled very quickly and can only be slowed down. This is because when the deceleration rate of the washing machine is too fast and exceeds the consumption rate relying on motor loss and the resistance of the washing machine's own mechanical friction, the excess energy will be fed back to the DC bus capacitor of the variable frequency drive, causing the bus capacitor voltage to increase, and even easily causing overvoltage breakdown of electronic devices, greatly increasing the risk of failure and making the operation of the washing machine prone to malfunction. Slow deceleration increases the washing time of the washing machine and reduces washing efficiency. Summary of the invention

[0005] The object of the present invention is to provide a four-quadrant operation washing machine variable frequency drive to solve the problems raised in the above background technology.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A four-quadrant washing machine variable frequency driver comprises a full-bridge boost circuit consisting of a PFC power switch tube and a bus capacitor. The full-bridge boost circuit is also connected to an AC input voltage source, a high-frequency PFC inductor, a current sampling resistor, a motor drive power switch tube, and an equivalent model of a controlled motor to form a complete circuit. Four PFC power switch tubes are provided, one bus capacitor is provided, six motor drive power switch tubes are provided, three current sampling resistors are provided, the AC input voltage source and the high-frequency PFC inductor are connected in series, the four PFC power switch tubes are divided into two groups, each group comprises two PFC power switch tubes connected in series, the two groups are connected in parallel, and the bus capacitor is connected in parallel to a group of circuits consisting of two PFC power switch tubes connected in series.

[0008] Preferably, the six motor drive power switch tubes are divided into three groups, each group includes two motor drive power switch tubes connected in series, and the three groups are connected in parallel with each other. Each group also includes a current sampling resistor.

[0009] Preferably, the torque of the equivalent model of the controlled motor is set as T, and the speed of the equivalent model of the controlled motor is set as ω. When the signs of T and ω are the same, that is, when T>0, ω>0 and T<0, ω<0, the energy flow direction of the complete circuit is from the grid side to the equivalent model of the controlled motor.

[0010] Preferably, when the signs of T and ω are different, that is, when T>0, ω<0 and T<0, ω>0, the energy flow direction of the complete circuit is from the equivalent model of the controlled motor to the grid side.

[0011] Preferably, the two ends of the series circuit of the AC input voltage source and the high-frequency PFC inductor are respectively connected to two groups of parallel circuits composed of four PFC power switch tubes, and are located between the two PFC power switch tubes on each series circuit.

[0012] Preferably, the three ports of the equivalent model of the controlled motor are respectively connected to three groups of parallel circuits composed of six motor drive power switch tubes, and are located between the two motor drive power switch tubes on each parallel circuit.

[0013] Preferably, the following algorithm is further included: The first step: Initialize the system parameters, including the AC voltage peak coefficient Kp, the set bus voltage regulation amount Vm, the minimum DC bus voltage Vdc.Min in the electric state, and the maximum DC bus voltage Vdc.Max in the power generation state. The second step: Sample the AC voltage, DC bus voltage, and AC current to obtain the effective value Vac.rms of the AC voltage and the actual bus voltage Vdc. The third step: Calculate the target bus voltage stable value Vdc.Ref in the electric state, and the formula is Vdc.Ref = Kp × Vac.rms + Vm, where Vm is the manually set bus voltage regulation amount. The fourth step: Judge whether Vdc.Ref < Vdc.Min? The fifth step: When Vdc.Ref < Vdc.Min, command Vdc.Ref = Vdc.Min, otherwise, enter the DC bus voltage stable control algorithm. The sixth step: Judge whether the actual bus voltage Vdc is greater than the maximum DC bus voltage Vdc.Max set by the operator according to the actual situation of the bus. If it is greater, enter the DC bus voltage stable control algorithm.

[0014] The beneficial effects of the present invention:

[0015] 1. The full-bridge boost circuit composed of four PFC power switch tubes and bus capacitors replaces the traditional diode rectifier bridge circuit, successfully realizing the bidirectional flow of energy, that is, energy is fed from the grid side to the equivalent model of the controlled motor and energy is fed back from the equivalent model of the controlled motor to the grid side, thus avoiding energy waste. In addition, since the washing machine can maintain a high deceleration rate without increasing the probability of electronic device loss, the operating efficiency of the washing machine is greatly improved. The structural design is exquisite and efficient, and has great application prospects.

[0016] 2. Through the design of algorithms and actuators, the DC bus voltage can be boosted efficiently, thereby improving the system efficiency of the washing machine during high-speed operation, reducing weak magnetic losses, and greatly improving the energy saving and environmental protection of the washing machine. At the same time, the input AC current harmonic adjustment and power factor correction are realized, successfully reducing the harmonic pollution of the power grid during the operation of the washing machine and improving the input system efficiency, thereby greatly improving the overall energy utilization rate of the washing machine. The design is exquisite, simple and efficient, and is suitable for promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described below in conjunction with the accompanying drawings.

[0018] Figure 1 is a complete circuit diagram of the present invention;

[0019] Figure 2 It is a quadrant representation diagram of the torque and speed of the equivalent model of the controlled motor in the present invention;

[0020] Figure 3 It is an input voltage and current waveform diagram in the present invention;

[0021] Figure 4 It is another input voltage and current waveform diagram in the present invention;

[0022] Figure 5 It is a connection diagram of the algorithm execution device in the present invention;

[0023] Figure 6 It is a control block diagram of the algorithm in the present invention.

[0024] In the figure: 1. AC input voltage source; 2. High-frequency PFC inductor; 3. PFC power switch tube; 4. Bus capacitor; 5. Current sampling resistor; 6. Motor drive power switch tube; 7. Equivalent model of the controlled motor. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] See also Figure 1-5 As shown, the present invention is a four-quadrant washing machine frequency conversion driver, including a full-bridge boost circuit composed of a PFC power switch tube 3 and a bus capacitor 4. The full-bridge boost circuit is also connected to an AC input voltage source 1, a high-frequency PFC inductor 2, a current sampling resistor 5, a motor drive power switch tube 6, and a controlled motor equivalent model 7, which together constitute a complete circuit, wherein four PFC power switch tubes 3 are provided, one bus capacitor 4 is provided, six motor drive power switch tubes 6 are provided, and three current sampling resistors 5 are provided. The AC input voltage source 1 and the high-frequency PFC inductor 2 are connected in series, and the four PFC power switch tubes 3 are divided into two groups, each group includes two PFC power switch tubes 3 connected in series, and the two groups are connected in parallel. The bus capacitor 4 is connected in parallel with a group of circuits composed of two PFC power switch tubes 3 connected in series.

[0027] By setting up a full-bridge boost circuit consisting of four PFC power switch tubes 3 and a bus capacitor 4, the traditional diode rectifier bridge circuit is replaced, and the two-way flow of energy is successfully realized, that is, energy is fed from one side of the power grid to the controlled motor equivalent model 7 and energy is fed back from the controlled motor equivalent model 7 to the power grid side, thereby avoiding energy waste. In addition, since the washing machine can maintain a higher deceleration rate without increasing the probability of electronic device loss, the operating efficiency of the washing machine is greatly improved. The structural design is exquisite and efficient, and it has great application prospects.

[0028] It should be noted that the six motor drive power switch tubes 6 are divided into three groups, each group includes two motor drive power switch tubes 6 connected in series, the three groups are connected in parallel, and each group also includes a current sampling resistor 5.

[0029] Furthermore, the torque of the controlled motor equivalent model 7 is set to T, and the speed of the controlled motor equivalent model 7 is set to ω. When T and ω have the same sign, that is, T>0, ω>0 and T<0, ω<0, the energy flow of the complete circuit is from the grid side to the controlled motor equivalent model 7. At this time, the waveforms of the input voltage and current are as follows: Figure 3 As shown, when the signs of T and ω are different, that is, T>0, ω<0 and T<0, ω>0, the energy flow of the complete circuit is the equivalent model of the controlled motor 7 flowing to the grid side. At this time, the waveforms of the input voltage and current are as follows: Figure 4 shown.

[0030] Among them, it should be noted that both ends of the series circuit of the AC input voltage source 1 and the high-frequency PFC inductor 2 are respectively connected to two groups of parallel circuits composed of four PFC power switching tubes 3, and between the two PFC power switching tubes 3 on each series circuit. Three ports of the equivalent model 7 of the controlled motor are respectively connected to three groups of parallel circuits composed of six motor drive power switching tubes 6, and between the two motor drive power switching tubes 6 on each parallel circuit.

[0031] Referring to Figure 6 As shown, the present invention further includes the following algorithm. The steps are as follows: The first step: Initialize the system parameters, including the AC voltage peak factor Kp, the set bus voltage adjustment amount Vm, the minimum DC bus voltage Vdc.Min in the electric state, and the maximum DC bus voltage Vdc.Max in the power generation state. The second step: Sample the AC voltage, DC bus voltage, and AC current to obtain the effective value Vac.rms of the AC voltage and the actual bus voltage Vdc. The third step: Calculate the target bus voltage stable value Vdc.Ref in the electric state. The formula is Vdc.Ref = Kp × Vac.rms + Vm, where Vm is the manually set bus voltage adjustment amount. The fourth step: Determine whether Vdc.Ref < Vdc.Min? The fifth step: When Vdc.Ref < Vdc.Min, command Vdc.Ref = Vdc.Min; otherwise, enter the DC bus voltage stable control algorithm. The sixth step: Determine whether the actual bus voltage Vdc is greater than the maximum DC bus voltage Vdc.Max set by the operator according to the actual situation of the bus. If it is greater, enter the DC bus voltage stable control algorithm.

[0032] Among them, the control algorithms for the AC current flow direction, the DC bus voltage stable control algorithm, and the AC current PF and harmonic control algorithms are all existing technologies and will not be elaborated here.

[0033] Among them, it should be noted that referring to Figure 5 As shown, iqBusVoltRef represents the DC bus voltage target reference, VoltLoop represents the voltage loop, Gcomb(s) represents the notch filter, Gu(s) represents the PID controller, iqVac represents the unit sine wave reference, iqlref represents the current target reference, CurrentLoop represents the current loop PID controller, VoltSystem represents the controlled system, iqBusVoltReal represents the actual bus voltage, Gcbus(s) represents the voltage sampling correction coefficient, A / D represents the digital ADC sampling, Gnbus represents the voltage sampling digital correction coefficient, and iqlReal represents the actual bus current.

[0034] Through the design of the above-mentioned algorithm and actuator, the DC bus voltage can be boosted efficiently, thereby improving the system efficiency of the washing machine during high-speed operation, reducing weak magnetic loss, and greatly improving the energy saving and environmental protection of the washing machine. At the same time, the input AC current harmonic adjustment and power factor correction are realized, successfully reducing the harmonic pollution of the power grid during the operation of the washing machine and improving the input system efficiency, thereby greatly improving the overall energy utilization rate of the washing machine. The design is exquisite, simple and efficient, and is suitable for promotion.

[0035] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. Four-quadrant operation washing machine inverter drive, characterized in that, It includes a full-bridge boost circuit composed of a PFC power switch tube (3) and a bus capacitor (4). The full-bridge boost circuit is also connected to an AC input voltage source (1), a high-frequency PFC inductor (2), a current sampling resistor (5), a motor drive power switch tube (6), and an equivalent model of the controlled motor (7) to jointly form a complete circuit. Among them, four PFC power switch tubes (3) are provided, one bus capacitor (4) is provided, six motor drive power switch tubes (6) are provided, three current sampling resistors (5) are provided. The AC input voltage source (1) and the high-frequency PFC inductor (2) are in series. The four PFC power switch tubes (3) are divided into two groups, each group includes two PFC power switch tubes (3) in series, and the two groups are in parallel. The bus capacitor (4) is in parallel with a group of circuits composed of two PFC power switch tubes (3) in series.

2. The four-quadrant operation washing machine inverter driver according to claim 1, characterized in that: The six motor drive power switch tubes (6) are divided into three groups, each group includes two motor drive power switch tubes (6) in series, and the three groups are in parallel with each other. Each group also includes a current sampling resistor (5).

3. The four-quadrant operation washing machine inverter driver according to claim 2, characterized in that: Set the torque of the equivalent model of the controlled motor (7) as T and the speed of the equivalent model of the controlled motor (7) as ω. When the signs of T and ω are the same, that is, when T>0, ω>0 and T<0, ω<0, the energy flow of the complete circuit is from the grid side to the equivalent model of the controlled motor (7).

4. The four-quadrant operation washing machine inverter driver according to claim 3, characterized in that: When the signs of T and ω are different, that is, when T>0, ω<0 and T<0, ω>0, the energy flow of the complete circuit is from the equivalent model of the controlled motor (7) to the grid side.

5. The four-quadrant operation washing machine inverter driver according to claim 4, characterized in that: Both ends of the series circuit of the AC input voltage source (1) and the high-frequency PFC inductor (2) are respectively connected to two groups of parallel circuits composed of the four PFC power switch tubes (3), and are located between the two PFC power switch tubes (3) on each series circuit.

6. The four-quadrant operation washing machine inverter driver according to claim 5, characterized in that: The three ports of the equivalent model of the controlled motor (7) are respectively connected to three groups of parallel circuits composed of six motor drive power switch tubes (6), and are located between the two motor drive power switch tubes (6) on each parallel circuit.

7. The four-quadrant washing machine inverter driver according to claim 1, characterized in that: It also includes the following algorithm: The first step: Initialize the system parameters, including the AC voltage peak factor Kp, the set bus voltage adjustment amount Vm, the minimum DC bus voltage Vdc.Min in the electric state, and the maximum DC bus voltage Vdc.Max in the generating state. The second step: Sample the AC voltage, DC bus voltage, and AC current to obtain the effective value Vac.rms of the AC voltage and the actual bus voltage Vdc. The third step: Calculate the target bus voltage stable value Vdc.Ref in the electric state. The formula is Vdc.Ref = Kp × Vac.rms + Vm, where Vm is the manually set bus voltage adjustment amount. The fourth step: Judge whether Vdc.Ref < Vdc.Min? The fifth step: When Vdc.Ref < Vdc.Min, command Vdc.Ref = Vdc.Min, otherwise, enter the DC bus voltage stable control algorithm. Step 6: Determine whether the actual bus voltage Vdc is greater than the maximum DC bus voltage Vdc.Max set by the operator according to the actual bus situation. If so, enter the DC bus voltage stabilization control algorithm.

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