JP2002374689A - Motor drive gear and washing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent concentration of heat and excessively strong braking forces to an inverter circuit, when a washing machine is DC-braked, and to drive an electric article during power supply interruption. SOLUTION: A motor driving gear is provided with the inverter circuit which inverts DC power into AC power and supplies the inverted AC power to a motor, a pre-driver circuit which drives the switching element of the inverter circuit, the drive power source of the inverter circuit, which is charged through the operation of the inverter circuit, and an inverter control means which performs PWM control. The inverter control means charges the drive power source of the inverter circuit, by continuously turning on one-phase negative pole-side switching elements of the inverter circuit and performs DC-braking, by PWM-operating the remaining other-phase positive pole-side switching elements of the inverter circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor driving device for braking an electric motor, and a washing machine equipped with the electric motor driving device.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a diagram illustrating a drive control device for a brushless motor disclosed in Japanese Patent Publication No. 1 (JP-A) No. 1; In the figure, 101 is a motor start / stop signal terminal, 102 is a torque control signal terminal, 103 is a control circuit, 104 is a brushless motor, 104u, 104v
And 104w are stator windings, 105 is a switching circuit, 106 is a brake command circuit, 107 is a rotation direction switching circuit, 108 is a DC brake circuit, 109 is a position detection circuit, 109u, 109v and 109w are Hall elements, 110u and 110v. And 110w are comparators, 111w
a and 111b are resistors, 112u, 112v and 112w
Is a power transistor.

Next, the operation will be described. When the motor start / stop signal goes low (motor start signal), the control circuit 103 turns on / off the switching elements in the switching circuit 105 and applies an AC voltage to the stator windings 104u to 104w of the brushless motor. The control circuit 103 performs PWM (Pulse Width Modulation) control on the switching circuit 105 according to the magnitude of the torque control signal, and controls the torque of the brushless motor 104.

When the brushless motor 104 starts, the Hall elements 109u, 109v and 109w of the position detection circuit 109 output an output voltage, and the output voltage is
u, 110v, and 110w, and is output to the control circuit 103 as a rectangular wave signal indicating a high level when the input voltage exceeds the reference voltage. Control circuit 10
3 performs a logical operation on the rectangular wave signal as a rotor position detection signal to obtain an energization timing signal, thereby turning on / off the switching element of the switching circuit 105 and bringing the brushless motor 104 into an operating state.

When the motor start / stop signal is changed to a high level (motor stop signal), the brake command circuit 106
Outputs a pulse having a fixed time width corresponding to a time interval for performing the reverse rotation braking operation and a rotation direction signal. The rotation direction switching circuit 107 reverses the direction of the current applied to the Hall elements 109u, 109v, and 109w between the output terminals 107a and 107b. As a result, the polarity of the detected magnetic field in the rotor of the brushless motor 104 is reversed, so that the phases of the signals output from the comparators 110u, 110v, and 110w to the control circuit 103 cause the brushless motor 104 to rotate in the reverse direction. The phase is output. The control circuit 103 performs a logical operation on the rectangular wave signals from the comparators 110u to 110w to obtain a reverse rotation energizing timing,
The switching element of the switching circuit 105 is turned on and off, and the brushless motor 104 generates reverse rotation torque. Such a reverse rotation braking operation is applied for a certain period of time.

[0006] When a trigger pulse serving as a DC operation start signal is output to the DC brake circuit 108, a pulse signal having a width corresponding to the time interval for performing the DC brake operation is output. The pulse signal is input to the signal output circuit 108b. Output to the control circuit 103. The control circuit 103 stops driving of the brushless motor 104 by stopping switching control of the switching circuit accordingly.

The signal output circuit 108b switches the power transistors 112u, 112v and 112w from the off state to the on state, and direct current flows from the u-phase to the v- and w-phase stator windings of the brushless motor so that the DC excitation is performed. Is performed, a braking operation by DC braking is performed, and the rotation of the brushless motor 104 is stopped.

[0008]

When the motor is decelerated and stopped by DC braking, a circuit (bootstrap circuit) for charging the drive power supply of the positive side switching element by turning on the negative side switching element in the inverter circuit. In the case of), if the switching element on the positive electrode side is continuously turned on, the drive power supply cannot be charged due to power consumption alone, and the voltage drop causes the switching element to become inoperable or to be destroyed. There were challenges.

In addition, during DC braking of the electric motor, the current of each phase becomes non-uniform and intensively flows through some switching elements of the inverter circuit. In this case, the switching elements that cause a concentrated current flow have a large loss, and the cooling capacity must be increased by increasing the size of the radiation fins. There was a problem that invited.

If the rotating body driven by the electric motor is stopped by a sudden braking force, the vibration of the device equipped with the electric motor is increased by the reaction, and the noise is increased.
There were problems such as the safety device operating due to abnormal vibration. In addition, since the motor generates an induced voltage, the current flowing when the DC voltage is applied pulsates greatly, and the vibration of the device mounted with the motor increases, and the noise increases. There were problems such as operation. In addition, when the motor is equipped with a magnet like a DC brushless motor, there has been a problem that the magnet is demagnetized by an excessive current and the reliability of the device is reduced.

In general, regenerative braking and reverse-phase braking are performed to decelerate or stop the motor. However, the braking force is insufficient in a low-speed region of the motor, and it takes a long time to stop. Also, when trying to obtain a large braking force in the high-speed range of the motor, the current flowing through the motor becomes extremely large, and the supply current of the inverter circuit and the allowable current of the motor become insufficient. There has been a problem that the current withstand capability must be increased, resulting in an increase in the size and cost of the circuit and the motor.

Many lid lock devices and the like of appliances such as washing machines are operated and released by electricity, and when an abnormal voltage drop including a power failure of a commercial power supply occurs, the operation is maintained and it is difficult to release. However, since the release was manually performed, there was troublesomeness. Further, since a buzzer or the like cannot be operated, there is no means for informing the user of the abnormal operation. This can be achieved by providing a separate power supply for releasing the lid lock device or issuing a buzzer or other notification when the power supply voltage is abnormally low, or by securing a space for accommodating them. There were problems such as inviting

The present invention has been made in order to solve the above-mentioned problems, and has a simple configuration and a simple method.
An object of the present invention is to provide an electric motor drive device with high safety and reliability, and a washing machine equipped with the electric motor drive device.

[0014]

According to the present invention, there is provided an electric motor driving apparatus comprising: a rectifier circuit for converting an AC power supply to a direct current; a smoothing circuit connected to the rectifier circuit for smoothing the direct current; An inverter circuit for connecting and arranging a series body of switching elements connected therebetween for each phase, converting DC power into AC power and supplying the AC power to the motor, a pre-driver circuit for driving the switching elements of the inverter circuit, and an inverter Inverter control means for turning on and off the switching elements of the circuit, wherein the inverter control means continuously turns on the one-phase negative-side switching element of the inverter circuit and performs the PWM operation on the other positive-side switching elements of the other phase. To perform DC braking.

The pre-driver circuit includes a driving power supply for the positive-side pre-driver circuit which is charged by another power supply when the switching element connected to the negative side of the smoothing circuit is turned on.

Further, the inverter control means operates so that the switching elements that perform the PWM operation output the same voltage value.

The inverter control means reduces the DC voltage applied to the motor by shortening the conduction period of the switching element that performs the PWM operation.

The inverter control means performs DC braking by sequentially switching the following steps in a three-phase inverter circuit. (A) The negative polarity switching element of the first phase is continuously turned on, and the positive polarity switching elements of the second and third phases are PW.
M driving; (b) continuous ON operation of the second phase negative switching element; PWM driving of the first and third phase positive switching elements; (c)
Driving the third-phase negative-side switching elements into a continuous ON operation, and driving the first and second-phase positive-side switching elements by PWM;

Further, the inverter control means includes a timer means, and sequentially switches each step at an arbitrary time interval set by the timer means.

Further, the inverter control means gradually increases the output voltage to an arbitrary set value after outputting the initial voltage from the inverter circuit for a certain period.

Further, the amount of change in the output voltage of the inverter circuit is changed according to the rotation speed of the motor.

The inverter control means switches to DC braking after reverse-phase braking.

The inverter control means decelerates by reverse phase braking when the motor rotates at a high speed, and detects that a certain number of rotations at a low speed has been reached, and switches to DC braking.

The inverter control means switches to DC braking after regenerative braking.

The inverter control means reduces the speed by regenerative braking when the motor is rotating at high speed, and switches to DC braking when it detects that the motor has reached a certain rotational speed at low speed.

A rectifier circuit for converting an AC power supply to DC, a smoothing circuit connected to the rectifier circuit for smoothing DC, and an inverter circuit for converting DC output power of the smoothing circuit into AC power and supplying the AC power to a motor. Inverter control means for controlling the speed of the motor, rotation speed detection means for detecting the rotation speed of the motor, power supply voltage detection means for detecting the voltage of the AC power supply, and electric components driven by the DC power supply of the smoothing circuit An electrical component driving means, and a determining unit for determining an abnormal voltage drop of the AC power supply, and when the determining unit determines that the voltage has dropped abnormally, the electric motor is regeneratively braked by the inverter circuit;
The electric component is driven by the obtained electric power.

Also, the electric parts are protection or safety devices,
After the determination unit determines that the abnormal decrease has occurred, the motor is decelerated to release the protection or safety function.

Further, the electric component is a sound generator, and after the judgment section judges that the abnormal decrease has occurred, the electric motor is decelerated to operate the sound generator.

Further, the motor is an induction motor.

A washing machine according to the present invention includes an outer tub, a rotatable rotary tub provided inside the outer tub, a stirring blade provided inside the rotary tub, and an electric motor for rotatingly driving the rotary tub and the stirring blade. An electric motor drive device according to any one of claims 1 to 16.

[0031]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. 1 to 6 are diagrams showing a first embodiment, FIG. 1 is a block diagram of an electric motor driving device, FIG. 2 is a circuit diagram showing a method of charging an upper arm power supply for one phase of an inverter circuit,
FIG. 3 is a voltage waveform diagram at the output terminal of the inverter circuit and an average voltage waveform diagram at the output terminal. FIG. 4 is a diagram illustrating the operation of the switching element. FIGS. 5 and 6 are control flow diagrams in the DC braking mode.

The electric motor driving device shown in FIG. 1 is mounted on an electric device such as a washing machine, and further includes components necessary for the electric device such as an actuator (not shown). In FIG. 1, 1 is an AC power supply, 2 is a rectifier circuit for converting AC to DC, 3 is a smoothing circuit for smoothing pulsating DC voltage, and 4 is an inverter circuit for converting DC voltage to AC of an arbitrary frequency and voltage. , A switching element and a rectifying element connected in antiparallel are connected in series up and down to form an arm,
Each arm is connected in parallel between the positive electrode and the negative electrode of the smoothing circuit 3 which is a DC power supply. Each is a U phase, a V phase, and a W phase. 5 is an electric motor such as an induction motor, 6 is a control circuit, a pre-driver 7 for driving a switching element of the inverter circuit 4, a rotational speed detecting means 9 for detecting a rotational speed of the electric motor 5, and a rotation signal from the rotational speed detecting means 9. And an inverter control means 8 having a waveform generation function for operating the inverter circuit 4 by inputting operation commands including a stop and rotation speed command.

Next, the operation will be described. In FIG. 1, when an operation command is input to the inverter control means 8, an inverter drive signal is generated and a drive signal is output to the pre-driver 7. The pre-driver 7 drives the switching element of the inverter circuit 4, converts the DC power of the smoothing circuit 3 into AC power having an arbitrary frequency and voltage, and outputs the AC power, thereby driving the electric motor 5. The rotation information of the rotation speed detection means 9 for detecting the rotation speed of the rotating shaft of the electric motor 5 is input to the inverter control means 8, and the motor 5 is rotated by varying the inverter output voltage and frequency so that the rotation speed becomes the operation command value. Perform numerical control.

In FIG. 2, reference numeral 13 denotes a high-voltage DC power supply (for example, dc150) obtained by rectifying and smoothing an AC power supply.
V), 10 is a low-voltage driving power supply (for example, dc15V),
11 is a resistor, 12 is a rectifying element, 14 is an upper arm switching element connected to the positive side of the DC power supply 13, 17 is a lower arm switching element connected to the negative side of the DC power supply 13, and upper and lower connected in series. The arm switching element is connected to DC power supply 13. Reference numeral 15 denotes an upper arm drive circuit for driving the upper arm switching element 14 by a photocoupler, a high-voltage IC, or the like, reference numeral 16 denotes an upper arm power supply which is a power supply for driving the upper arm drive circuit 15, and reference numeral 18 denotes a lower drive for driving the lower arm switching element. This is an arm drive circuit. Reference numeral 19 denotes an output terminal in which the upper arm switching element 14 and the lower arm switching element 17 are connected in series and connected to the motor 5.

The operation of the switching element in the inverter circuit 4 will be described with reference to FIG. At the start of the operation of the inverter circuit 4, a precharge sequence for charging the upper arm power supply 16 is provided. In the precharge sequence, an ON signal is input to the lower arm drive circuit 18 connected to the drive power source 10 for a certain period, and the lower arm switching element 1
7, the resistor 11 connected to the drive power source 10,
The charging current Ic is supplied via a path indicated by a dotted line via the rectifying element 12, the upper arm power supply 16, and the lower arm switching element 17.
, The upper arm power supply 16 is charged and completed.

Thereafter, the upper arm switching element 14 can be driven. When driving the upper arm switching element 14 or the lower arm switching element 17, after a lapse of a fixed time (dead time) for preventing a short circuit of the DC power supply 13 when the upper arm switching element 14 and the lower arm switching element 17 are simultaneously turned on. , One of the switching elements is turned on. Here, since the upper arm power supply 16 is consumed by the upper arm drive circuit 15 and the upper arm switching element 14 and its voltage decreases, the continuous ON operation time of the upper arm switching element 14 is limited. The drive circuit here is of a bootstrap type in which the drive power of the upper arm switching element is charged when the lower arm switching element 17 is turned on. The upper arm power supply 16 may be charged from another power supply having the same voltage level as the drive power supply 10.

In FIG. 3, the horizontal axis represents the phase θ, the vertical axis represents the voltage, UV represents the line voltage, and U, V and W represent the terminal voltage of each phase. This is a two-phase modulation method in which any one of the U, V, and W phase switching elements performs a continuous ON operation and the other phase switching element performs a switching operation, and shows a waveform at the time of arbitrary voltage output. VH is a section in which the upper arm switching element is continuously turned on and the voltage P on the positive side of the DC power supply 13 is output. VL is a section in which the lower arm switching element is continuously turned on and the voltage N on the negative side of the DC power supply 13 is output.

A section other than VH and VL is a section in which the switching element performs a switching operation and outputs an intermediate average voltage between the positive and negative voltages of the DC power supply 13. Since data obtained by modulating a part of the sine wave is used in this section, the fundamental wave component is output as a sine wave voltage waveform between the output terminals 19 of each phase of the inverter circuit 4. This is a driving method used to perform high-efficiency driving and low-noise driving of the electric motor.

When the electric motor 5 is driven, the inverter control means 6
After the precharge sequence for charging the upper arm power supply 16 is completed, each phase of the inverter circuit 4 operates to output the voltage shown in FIG. At this time, a sinusoidal current flows from the output terminals 19 of the inverter circuit 4 to the motor 5, thereby realizing low-vibration and low-noise motor driving with little torque ripple. In addition, a time period (dead time) is provided for simultaneously turning off the upper arm switching element 14 and the lower arm switching element 17 for a certain period of time to prevent a short circuit of the DC power supply 13.

In FIG. 4, the columns of the table are the inverter circuits 4
In each phase, the row shows the operation mode and corresponds to the phase θ in FIG. The symbols in the table indicate the operation states of the switching elements of the inverter circuit 4, where P indicates switching (PWM) operation by ON / OFF, and L indicates the case where the lower arm switching element 17 is continuously ON.

The DC braking for decelerating and stopping the motor 5 will be described. 4, in a mode a, the lower arm switching element 17 of the U phase is continuously turned on, and the upper arm switching element 14 of the V and W phases is PWM-driven. Since a DC current flows from the V and W phases of the electric motor 5 to the U phase, the electric motor 5 is DC-excited and a braking force is applied, so that the rotation speed is reduced.

In the mode b, the V-phase lower arm switching element 17 is continuously turned on, and the U- and W-phase upper arm switching elements 14 are PWM-driven. As a result, a direct current flows from the U and W phases of the motor 5 to the V phase.
Is excited by a direct current to apply a braking force, and the rotational speed decreases.

In the mode c, the lower arm switching element 17 of the W phase is continuously turned on, and the upper arm switching element 14 of the U and V phases is PWM-driven. As a result, a DC current flows from the U and V phases of the motor 5 to the W phase.
Is excited by a direct current to apply a braking force, and the rotational speed decreases.

In the modes a to c, since a direct current flows in each phase, a larger braking force can be obtained as compared with the case where only one phase flows. In addition, since a DC current flows from two switching elements that perform on-off operation to one switching element that performs continuous on-operation, the difference between the loss of each element is reduced and the difference in temperature rise between the switching elements is reduced. This is because the switching loss that occurs when the switching element performs the switching operation is greater than the ON loss that occurs when the switching element performs the continuous ON operation.

The conduction period of the two switching elements to be turned on / off is shortened (the on-duty is reduced) to reduce the electric motor 5
The pulsating current is suppressed regardless of the induced voltage of the motor 5 by reducing the DC voltage applied to the motor 5 and the DC current value flowing through the motor 5, thereby suppressing the fluctuation of the braking force due to the pulsating current. Prevents product vibration and noise due to sudden braking force. In addition, by making the on-duties of the two switching elements that are turned on and off equal, the currents flowing through the switching elements can be made equal.

If the switching element is turned on and off at the timing when a current flows through the motor 5, a larger switching loss occurs than when the switching element is continuously turned on. Therefore, the element temperature rises and the tolerance for the allowable temperature is reduced. Become. Exceeding the permissible loss of the switching element leads to thermal destruction, so it is necessary to reduce the element loss,
In general, measures such as increasing the switching speed are taken, but the generated noise increases.Therefore, as described above, by sequentially switching the switching elements that are continuously turned on, the loss of the switching elements is dispersed. This prevents loss from concentrating on one switching element and causing thermal destruction. It also prevents an increase in the current capacity of the switching element.

In the above description, the modes a to c are sequentially switched so that the loss is not concentrated on one switching element. However, if no problem such as circuit destruction occurs, any of the modes a to c is used. DC braking may be performed in any one of the modes. Thereby, the loss of the circuit can be reduced. In addition, a large braking force is obtained because a current for braking is applied to all phases of the electric motor. Further, DC braking of the electric motor can be performed while securing the power supply of the upper arm drive circuit.

While the motor 5 is being driven, the inverter control means 8
, A DC braking sequence is entered to stop the motor 5 being driven, and the motor 5 is operated in the DC braking mode shown in FIG. In STP1, the phase θo at which the lower arm switching element 17 performs the continuous ON operation is set. Here, it is assumed that the lower arm switching element 17 of the W phase continuously performs the ON operation, and the other U and V phases are the phases in which the PWM operation is performed. In STP2, the output voltage V of the phase that performs the PWM operation is set. Here, in order to make the average output voltages of the U and V phases the same, the voltage is output at the phase (dotted line) at the midpoint of the W phase VL period in FIG.

At STP3, the time T0 for outputting the phase at STP1 is set in the timer. In STP4, the inverter circuit 4 operates, the lower arm switching element 17 of the W phase continuously turns on, and the upper arm switching elements 14 of the other U and V phases perform switching operation by on / off. It flows and the braking force works,
The rotation speed of the electric motor 5 decreases.

At STP5, it is determined whether or not the rotational speed N of the electric motor 5 has been reduced to a low-speed rotational speed N1 which can be regarded as stopped or almost stopped. If it is less than N1, the process proceeds to STP9, where DC braking is stopped, and this flow ends. If N1 or more, the process proceeds to STP6 to determine whether the timer value T0 has elapsed.
If T0 has not elapsed, DC braking is continued. When T0 has elapsed, the process proceeds to STP7, in which the DC braking is temporarily stopped, and proceeds to STP8 to set the phase. Here, U
The lower-arm switching element of each phase performs a continuous ON operation, and the other V and W phases are phases in which the PWM operation is performed.

Next, in STP2, the output voltage V of the phase that performs the PWM operation is set. Here, in order to make the output voltages of the V and W phases the same, the voltage is output at the phase at the midpoint of the U-phase VL period in FIG. Thereafter, the above operation is performed. At the time of DC braking, the phases of continuous ON and PWM driving are decelerated by sequentially changing the modes a, b, and c in FIG. 4 for each timer T0 until the rotation speed reaches a predetermined rotation speed regardless of the rotation speed of the electric motor 5 to stop. Reach.

Although the output voltage is kept constant in FIG. 5, FIG. 6 shows a method of gradually increasing the applied voltage after the start of DC braking. In STP11, the output voltage V of the phase that performs the PWM operation is set. For example, as in the flow of FIG.
In order to make the output voltages of the V phase and the V phase the same, the voltage is output at the phase at the midpoint of the W phase VL period in FIG. S
In TP12, the time T1 for outputting the phase in STP11
To the timer. In the STP 13, the inverter circuit 4 operates, the lower arm switching element 17 of the W phase continuously turns on, and the upper arm switching elements 14 of the other U and V phases perform switching operation by on / off.
A direct current flows through the motor 5 to apply a braking force.
Rotation speed decreases.

At STP14, it is determined whether or not the rotation speed N of the electric motor 5 has been reduced to a low-speed rotation speed N1 which can be regarded as stopped or almost stopped. If it is less than N1, the process proceeds to STP17, where DC braking is stopped, and this flow ends. If N1 or more, the process proceeds to STP15 to determine whether the timer value T1 has elapsed. If T1 has not elapsed, the process proceeds to STP13, and DC braking is continued. If T1 has passed, STP
Proceed to 16 to set a voltage obtained by adding ΔV to the output voltage.
Next, the process proceeds to STP12, and T1 is set in the timer.
Thereafter, the above operation is performed. Here, the voltage change ΔV is shown as being constant, but may be changed according to the rotation speed of the electric motor 5 or the like.

The reverse-phase braking is a method of obtaining a braking force by changing the phase sequence of the output voltage of the inverter circuit 4.
When the motor 5 rotates at a high speed, the reverse phase braking can obtain a larger braking force than the DC braking, and when the motor 5 is rotating at a low speed, a sufficient braking force cannot be obtained with the reverse braking. Therefore, during braking, there is no adverse effect due to vibration, noise, etc. of the device, and the motor 5
In order to stop the rotation, the motor is decelerated by the reverse-phase braking at the time of high-speed rotation, and when the rotation reaches a certain number of rotations at the time of low-speed rotation, it is switched to DC braking. Here, if an induction motor is used as the motor, there is no concern about deterioration in motor characteristics due to demagnetization due to excessive current, unlike a DC brushless motor using a magnet for the rotor of the motor.

In the regenerative braking, when the output frequency of the inverter circuit 4 is reduced while the motor 5 is being driven by the inverter circuit 4, the electric power is generated by the motor 5 so that the electric power is supplied from the motor 5 to the smoothing circuit via the inverter circuit 4. 3 is a method of obtaining a braking force. When the motor 5 rotates at high speed, regenerative braking can obtain a larger braking force than DC braking, and when rotating at low speed, regenerative braking cannot obtain sufficient braking force. Therefore, in order to stop the motor 5 in a short time without any adverse effects due to vibrations and noises of the equipment at the time of braking, the motor 5 is decelerated by regenerative braking at high speed rotation, Switch to braking. Here, if an induction motor is used as the motor, there is no concern about deterioration in motor characteristics due to demagnetization due to excessive current, unlike a DC brushless motor using a magnet for the rotor of the motor.

Embodiment 2 7 to 9 show a second embodiment, FIG. 7 is a block diagram of an electric motor driving device, FIG. 8 is a cross-sectional view showing an internal structure of a washing machine, and FIG. FIG. 5 is a flowchart showing an operation of the washing machine in a mode in which the electric motor cannot be driven by the power supplied from the AC power supply. The electric motor driving device is mounted on an electric device such as a washing machine, and further includes components necessary for the electric device such as an actuator (not shown).
1 are denoted by the same reference numerals. In FIG. 7, 1
Is an AC power supply, 2 is a rectifier circuit for converting AC to DC, 3 is a smoothing circuit for smoothing pulsating DC voltage, 4 is an inverter circuit for converting DC voltage to AC of an arbitrary frequency and voltage, and a switching element and a reverse circuit. The rectifiers connected in parallel are connected in series up and down to form arms, and each arm is connected in parallel between the positive electrode and the negative electrode of the smoothing circuit 3 which is a DC power supply. Each is a U phase, a V phase, and a W phase. Reference numeral 5 denotes an electric motor such as an induction motor.

Reference numeral 6 denotes a control circuit, which is a pre-driver 7 for driving the switching element of the inverter circuit 4, a rotation speed detection means 9 for detecting the rotation speed of the electric motor 5, a rotation signal from the rotation speed detection means 9, a stop and a rotation speed. Inverter control means 8 having a waveform generation function for inputting an operation command including a command and operating the inverter circuit, power supply voltage detection means 20 for detecting the voltage of AC power supply 1, and DC for detecting the DC voltage of smoothing circuit 3 The determination unit 22 receives the detection voltage values from the voltage detection unit 21, the power supply voltage detection unit 20, and the DC voltage detection unit 21, and outputs a comparison result with a preset set value to the inverter control unit 8. It is constituted by electric component driving means 23 which is connected and driven.

In FIG. 7, when an operation command is input to the inverter control means 8, an inverter drive signal is generated and output to the pre-driver 7. The pre-driver 7 drives the switching element of the inverter circuit 4, converts the DC power of the smoothing circuit 3 into AC power having an arbitrary frequency and voltage, and outputs the AC power, thereby driving the electric motor 5. The rotation information of the rotation speed detection means 9 for detecting the rotation speed of the rotating shaft of the motor 5 is input to the inverter control means 6, and the motor 5 is rotated by varying the inverter output voltage and frequency so that the rotation speed becomes the operation command value. Perform numerical control.

The power supply voltage detecting means 20 detects the voltage value of the AC power supply 1, and determines a power failure or an abnormal voltage drop at which the inverter circuit 4 cannot drive the motor 5 by the determining section 22, 8 and output the result.
In the case of a stop command, the inverter control means 8 controls the motor 5
Decelerate and stop by electric braking.

Of the electric braking, in the regenerative braking, the inverter control means 8 converts the rotational energy of the electric motor 5 into electric energy and returns the electric energy to the smoothing circuit 3, so that the voltage of the smoothing circuit increases. The determination unit 22 determines whether or not the DC voltage value detected at 21 is equal to or greater than a predetermined value.
Reduce regenerative energy or temporarily stop regenerative braking.

In FIG. 8, reference numeral 24 denotes an outer frame of the washing machine;
Is a mounting foot attached to the bottom of the washing machine, 26 is a water supply valve for supplying water for washing and rinsing, 27 is a lid attached to the upper surface of the main body of the washing machine and opened and closed when taking in and out laundry, 28 is washing Lid locking means for locking the lid 27 so that the lid 27 does not open therein; 29, an outer tub for storing water during a washing or spin-drying process; 30, a stirring blade;
Is a freely rotating inner tank mounted in the outer tank 29, 32
Is an anti-vibration spring, 33 is a support rod, and the outer tub 29 is supported on the outer frame 24 by a plurality of support rods 33 and an anti-vibration spring 32.

Numeral 34 denotes a clutch / rotation prevention device which is a meshing type and has a function of transmitting driving force to the inner tub 31 and a clutch function for intermittent operation, and a function of stopping rotation of the inner tub 31 during washing. 35a is a pulley a attached to the rotating shaft of the clutch / rotation prevention device, 5 is an electric motor, 35b is a pulley b attached to the rotating shaft of the electric motor 5, and 36 is a pulley a35.
The belt and the agitating blade 30 attached between a and the pulley b35b are attached to the rotating shaft of the clutch / rotation prevention device. 37 is a drain valve, 38 is a drain hose, 39 is a controller which has an operation unit and a display unit of the washing machine, and drives an electromagnetic valve, an electric motor and other actuators necessary for the washing machine. Other parts necessary for the washing machine are omitted and not shown.

FIG. 8 shows an example in which the above-described electric motor driving device is mounted on a washing machine. First, the operation of a general washing machine will be described. In the washing process, after putting laundry and detergent into the inner tub 31, the water supply valve 26 is opened and a predetermined amount of tap water is supplied to the outer tub 2.
Store in 9. By closing the water supply valve 26 and rotating the electric motor 5, the pulley b35b, the belt 36, the pulley a35
a, The driving force is transmitted to the stirring blade 30 via the clutch / rotation prevention device 34 to rotate. When the electric motor 5 rotates forward and backward, the stirring blade 30 also repeats forward and reverse rotation, and the water and the laundry in the inner tub 31 are stirred. After the stirring blade 30 is rotated forward and backward for a predetermined time, the operation of the stirring blade 30 is stopped, the drain valve 37 is opened, and the water in the outer tank 29 is discharged to the outside of the main body by the drain hose 38. After draining is completed, the drain valve 37 is closed to end the washing process.

In the rinsing step, the water supply valve 26 is opened to store a predetermined amount of tap water in the outer tank 29. The water supply valve 26 is closed, the electric motor 5 is rotated, and the pulley b35b, the belt 36, the pulley a
35a, the driving force is transmitted to the stirring blade 30 via the clutch / rotation prevention device 34, and the stirring blade 30 rotates. When the electric motor 5 rotates forward and backward, the stirring blade 30 also repeats forward and reverse rotation, and the water and the laundry in the inner tub 31 are stirred. After the stirring blade 30 is rotated forward and backward for a predetermined time,
The operation of the stirring blade 30 is stopped, the drain valve 37 is opened, and the water in the outer tank 29 is discharged to the outside of the main body by the drain hose 38. After draining is completed, the drain valve 37 is closed to end the rinsing step.

In the dehydrating step, the lid 2 is
Lock 7 so that it cannot be opened from outside. The drain valve 37 is opened, and the clutch / detent device 34 is operated. By rotating the electric motor 5, the pulley b35b, the belt 36, the pulley a
35a, the driving force is transmitted to the inner tank 31 via the clutch / rotation prevention device 34, and the inner tank 31 rotates. By rotating the inner tub 31 at high speed, water contained in the laundry is blown into the outer tub 29 by centrifugal force. This water is discharged to the outside of the main body via the drain valve 37 and the drain hose 38. After a lapse of a predetermined time, a brake by electric braking is applied by the electric motor 5 to stop the inner tank 31 rotating at a high speed. After the motor 5 is stopped, the operation of the lid locking means 28 is released so that the lid 27 can be opened.

A series of operations in each of the above-described steps and the driving of the electric motor 5 are operated by the controller 39. Further, the washing step, the rinsing step, and the dehydrating step are performed a plurality of times depending on the degree of dirt and the setting of the user.

The power supply voltage detecting means 20 detects the voltage value of the AC power supply 1, and the judging section 22 judges a power failure or an abnormal voltage drop which makes it impossible to drive the motor 5 by the inverter circuit 4. The case where the electric motor 5 is stopped at will be described with reference to the flowchart of FIG.

In FIG. 9, the STP 20 determines whether the voltage value of the AC power supply 1 detected by the power supply voltage detecting means 20 is equal to or less than a set value V0. If it is equal to or lower than V0, the process proceeds to STP21, and it is determined whether the rotation speed of the electric motor 5 is equal to or higher than N2 (during high-speed rotation). If the motor is rotating at high speed, the process proceeds to STP22, and the drive of the electric motor 5 is stopped.

At STP23, the electric brake is operated. Here, an electric brake by regenerative braking is used. S
In TP24, it is determined whether or not the rotation speed N of the electric motor 5 has been reduced to a low-speed rotation speed N1 that can be regarded as stopped or almost stopped. If N1 or more, the process proceeds to STP23, and the electric brake is continued. If the electric motor 5 is less than N1, the process proceeds to STP25, and the electric brake is stopped. At STP26, the lid lock of the washing machine is released. At STP27, a sound generator such as a buzzer is operated to notify the user of the abnormal stop.

When the power supply of the smoothing circuit 3 is sufficient, the regenerative braking provides sufficient braking force when the motor 5 rotates at high speed, but does not provide sufficient braking force when rotating at low speed. Alternatively, it may be detected that the rotational speed has dropped to an arbitrary value, and the mode may be switched to DC braking. Electric braking can also be used during a normal dehydration step.

The washing machine equipped with the electric motor drive device according to the second embodiment has a relatively small vibration during DC braking.
The outer tub 29 is fixed by the vibration-proof spring 32 attached to the support rod 33.
Therefore, the vibration and noise of the product body are reduced.

When a large braking force is generated at once, such as at the moment when a braking force is applied to the inner tank 31 rotated by the electric motor 5,
A large force is applied between the outer tub 29 and the outer tub 2.
9 may vibrate greatly, and the vibration may not be absorbed by the anti-vibration spring 32 attached to the support rod 33, and the outer frame 24 may vibrate to generate sound. With this anti-vibration structure, it is difficult to reduce the vibration, and it is necessary to set the applied voltage to a level that allows low vibration. To prevent this, the initial applied voltage during DC braking must be reduced. By increasing the pressure gradually, a sudden braking force is prevented.

Although the details of the structure and operation are omitted here, the above-mentioned washing machine is a general washing machine that performs washing, rinsing, dehydration and the like.

Next, the electric power of the smoothing circuit 3 obtained by the regenerative braking is used for releasing the lid locking means 28 of the washing machine, and a sound generation device such as a buzzer in the controller 39 abnormally informs the user. A stop can be signaled.

In the above embodiment, a washing machine has been described. However, the same effect can be obtained by applying the present invention to a motor drive device using an inverter mounted in a refrigerator, an air conditioner, a ventilation fan, or the like.

[0076]

The motor driving apparatus according to the present invention performs DC braking by causing the one-phase negative-side switching element of the inverter circuit to perform a continuous ON operation and the remaining other-phase positive-side switching elements to perform a PWM operation. Loss can be reduced.
In addition, a large braking force is obtained because a current for braking is applied to all phases of the electric motor.

The driving power supply for the positive pre-driver circuit is charged by another power supply when the switching element connected to the negative side of the smoothing circuit is turned on, so that the driving power supply for the positive pre-driver circuit is secured. However, DC braking of the electric motor becomes possible.

Further, since the switching elements that perform the PWM operation are operated so as to output the same voltage value, current is not concentrated on some semiconductor elements, and element destruction due to heat concentration can be prevented.

Further, the pulsating current is suppressed irrespective of the induced voltage of the motor by shortening the conduction period of the switching element that performs the PWM operation to lower the DC voltage applied to the motor, and the braking force due to the pulsating current is reduced. And vibration and noise from the motor-equipped device due to a sudden braking force can be reduced.

Further, in the three-phase inverter circuit, the negative side switching element which is continuously turned on and the positive side switching element which is switched are sequentially switched, so that current is not concentrated on some semiconductor elements but is concentrated on heat. Element destruction can be prevented. In addition, there is no current concentration on a certain phase of the motor, so that demagnetization of the magnet is eliminated.

Further, since the negative side switching element that continuously turns on and the positive side switching element that performs the switching operation are sequentially switched by a timer, the loss of the switching elements can be equalized for each element, and element destruction due to heat concentration can be prevented. Can be prevented, and the reliability of the parts is further improved.

In addition, during DC braking, the inverter circuit outputs a low voltage for a certain period and then gradually increases the output to an arbitrary set value, so that the pulsating current is suppressed regardless of the induced voltage of the motor. In addition to suppressing the fluctuation of the braking force due to the pulsating current, the motor-equipped device is equipped with a sudden braking force without suddenly applying excessive braking force to the rotating body driven by the motor. It is possible to reduce vibration and noise from the device.

Further, since the change in the output voltage of the inverter circuit is changed in accordance with the rotation speed of the motor, the effect of suppressing the instantaneous application of excessive braking force to the rotating body driven by the motor is further improved. Is done.

Further, by switching to DC braking after reverse-phase braking, the motor can be reliably stopped in a short time.

Further, the motor is more reliably stopped in a short time by decelerating by reverse phase braking when the motor is rotating at a high speed, detecting that a certain number of rotations at a low speed is reached, and switching to DC braking. Can be done.

Also, the inverter control means can reliably stop the motor in a short time by switching to DC braking after regenerative braking.

Further, the inverter control means decelerates the motor by regenerative braking when the motor is rotating at a high speed, detects that a certain number of rotations at a low speed has been reached, and switches to DC braking to more reliably operate the motor for a short time. Can be stopped with.

Further, even in a situation where the power supply voltage is abnormally reduced such as a power failure, the motor is safely and reliably stopped by the regenerative braking by the inverter circuit, and the electric power obtained by the regenerative braking is used for driving the electric parts. And save energy.

Further, the electric power obtained by the regenerative braking can be used for the protection or the release of the safety device, and the protection or the safety device can be released without waiting for the return of the power supply voltage. Also.

Further, the electric power obtained by the regenerative braking can be used for driving a sound generating device or the like, which saves energy.

Further, since the induction motor is used as the motor,
Like a DC brushless motor using a magnet for the rotor of an electric motor, there is no need to worry about deterioration of motor characteristics due to demagnetization of the magnet due to excessive current, and a highly reliable device can be provided.

In the washing machine according to the present invention, it is possible to reduce circuit loss and prevent element destruction due to heat concentration at the time of electric braking of the electric motor, thereby preventing excessive braking force and reducing vibration and noise. It becomes. Further, the power generated during electric braking can be effectively used at the time of a power failure without increasing costs and adding components.

[Brief description of the drawings]

FIG. 1 is a view showing a first embodiment and is a block diagram of a motor drive device.

FIG. 2 is a diagram showing the first embodiment and is a circuit diagram showing a method of charging an upper arm power supply for one phase of an inverter circuit.

FIG. 3 is a diagram illustrating the first embodiment, and is a voltage waveform diagram of an output terminal of the inverter circuit.

FIG. 4 shows the first embodiment and is an explanatory diagram of an operation of the switching element.

FIG. 5 shows the first embodiment, and is a control flow chart in the DC braking mode.

FIG. 6 shows the first embodiment, and is a control flow chart in the DC braking mode.

FIG. 7 shows the second embodiment and is a block diagram of a motor drive device.

FIG. 8 shows the second embodiment, and is a cross-sectional view showing the internal structure of the washing machine.

FIG. 9 shows the second embodiment, and is a flowchart showing an operation of the washing machine in a mode in which the electric motor cannot be driven by the power supplied from the AC power supply when an abnormal voltage drop including a power failure of the AC power supply occurs.

FIG. 10 is a diagram illustrating a conventional drive control device for a brushless motor.

[Explanation of symbols]

1 AC power supply, 2 rectifier circuit, 3 smoothing circuit, 4 inverter circuit, 5 motor, 6 inverter control means, 7
Pre-driver, 8 inverter control means, 9 rotation speed detection means, 10 drive power supply, 11 resistor, 12 rectifying element, 13 DC power supply, 14 upper arm switching element, 15 upper arm drive circuit, 16 upper arm power supply, 17
Lower arm switching element, 18 lower arm drive circuit, 19 output terminal, 20 power supply voltage detecting means, 22
Judgment unit, 23 Electric component driving means, 24 Outer frame, 25
Mounting foot, 26 water supply valve, 27 lid, 28 lid locking means, 29 outer tub, 30 stirring blade, 31 inner tub, 32 anti-vibration spring, 33 support rod, 34 clutch / rotation prevention device, 35a pulley a, 35b pulley b , 36 belts, 37 drain valves, 38 drain hoses, 39 controllers.

 ──────────────────────────────────────────────────の Continuation of the front page (72) Inventor Yosuke Shinomoto 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Inside Mitsubishi Electric Corporation (72) Inventor Kenji Kawagishi 2- 2-3 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Co., Ltd. (72) Inventor Masami Yorita 1-1-1 Yamate, Funabashi-shi, Chiba F-term (reference) in Nippon Steel Corporation 3B155 HB09 HB24 LC15 MA01 MA06 MA07 MA09 5H530 AA05 BB06 CC11 CC25 CE12 CE13 CE16 CE25 CE26 DD03 DD05 DD13 DD24 DD28 EE05 5H576 AA12 DD02 DD04 EE09 EE11 FF04 GG02 HA04 HB02 LL01 LL24

Claims (17)

[Claims] A rectifier circuit for converting an AC power supply to a DC power;
A smoothing circuit connected to this rectifier circuit for smoothing direct current, and a series body of switching elements connected between a positive electrode and a negative electrode of the smoothing circuit are connected and arranged for each phase, and convert DC power into AC power to produce an electric motor. An inverter circuit to be supplied; a pre-driver circuit for driving a switching element of the inverter circuit; and inverter control means for controlling on / off of the switching element of the inverter circuit. The negative switching element of the phase is continuously turned on, and the positive switching element of the other phase is subjected to PWM (Pulse Width Modulation).
pulsation modulation) to perform DC braking. 2. The pre-driver circuit according to claim 1, further comprising a driving power supply for a positive-side pre-driver circuit charged by another power supply when a switching element connected to a negative side of the smoothing circuit is turned on. The motor drive device according to claim 1. 3. The motor driving device according to claim 1, wherein the inverter control means operates such that the switching elements that perform the PWM operation output the same voltage value. 4. The motor driving device according to claim 1, wherein the inverter control means reduces a DC voltage applied to the motor by shortening a conduction period of a switching element that performs a PWM operation. . 5. The motor driving device according to claim 1, wherein the inverter control means performs DC braking by sequentially switching the following steps in the three-phase inverter circuit. (B) driving the negative-side switching element of the first phase in a continuous ON operation, and driving the positive-side switching elements of the second and third phases by PWM;
(C) continuously turning on the negative-side switching elements of the first phase and the third-phase positive-side switching elements of the first and third phases; and (c) continuously turning on the negative-side switching elements of the first and third phases. Driving the positive-side switching element of the second phase by PWM. 6. The motor driving device according to claim 5, wherein the inverter control means includes a timer means, and the steps are sequentially switched at arbitrary time intervals set by the timer means. 7. The method according to claim 1, wherein the inverter control means outputs an initial voltage from the inverter circuit for a certain period, and then gradually increases the output voltage to an arbitrary set value. The electric motor driving device according to the above. 8. The motor driving device according to claim 7, wherein the amount of change in the output voltage of the inverter circuit is changed according to the number of revolutions of the motor. 9. The motor drive device according to claim 1, wherein the inverter control means switches to DC braking after antiphase braking. 10. The inverter control means decelerates by reverse-phase braking when the motor is rotating at high speed, and switches to DC braking when it detects that a certain number of rotations has been reached at low speed. An electric motor driving device as described in the above. 11. The motor drive device according to claim 1, wherein the inverter control means switches to DC braking after regenerative braking. 12. The inverter control means according to claim 11, wherein the motor is decelerated by regenerative braking when the motor is rotating at high speed, and switches to DC braking upon detecting that a certain number of rotations is reached at low speed. Motor drive. 13. A rectifier circuit for converting an AC power supply to a direct current, a smoothing circuit connected to the rectifier circuit for smoothing a direct current, and an inverter circuit for converting a direct current output power of the smoothing circuit to an alternating current power and supplying the alternating current power to the electric motor. Inverter control means for controlling the speed of the motor, rotation speed detection means for detecting the rotation speed of the motor, power supply voltage detection means for detecting the voltage of the AC power supply, and DC power supply of the smoothing circuit An electric component driving unit that drives an electric component, and a determination unit that determines an abnormal voltage drop of the AC power supply.If the determination unit determines that the voltage is abnormally low, the inverter circuit regeneratively brakes the electric motor. And an electric motor driving device for driving the electric component with the obtained electric power. 14. The motor drive according to claim 13, wherein the electric component is a protection or safety device, and after the determination section determines that the abnormality is abnormally reduced, the motor is decelerated to release the protection or safety function. apparatus. 15. The electric motor driving device according to claim 13, wherein the electric component is a sound generating device, and after the judgment section judges that the abnormal decrease has occurred, the electric motor is decelerated to operate the sound generating device. 16. The motor driving device according to claim 1, wherein the motor is an induction motor. 17. An outer tub, a rotatable rotary tub provided inside the outer tub, a stirring blade provided inside the rotary tub, an electric motor for rotatingly driving the rotary tub and the stirring blade, and
A washing machine, comprising: the electric motor drive device according to any one of claims 6 to 10.