JPH09238479A - Inverter equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce cost, improve efficiency, restrain vibration and noise, prevent breakdown of elements, enlarge a control range, and increase the starting torque of an induction motor. SOLUTION: This inverter equipment has the following; switching elements 4a, 4b and switching elements 4c, 4d which are connected in series between a power supply line and a ground line, a load connected between the connection point of the switching elements 4a, 4b and the connection point of the switching elements 4c, 4d, and inverter control means 9, 11, 12 having a first mode and a second mode. The first mode controls the elements in the manner in which one of the switching elements 4a, 4b turns on and the other turns on or on/off, in the OFF state of the switching elements 4b, 4c. The second mode controls the elements in the manner in which one of the switching elements 4b, 4c turns on and the other turns on or on/off, in the OFF state of the switching elements 4a, 4d. An AC voltage from a commercial power supply 1 is rectified by a rectifying means 2, and the rectified waveform voltage is supplied to a power supply line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device, and more particularly to an inverter device for controlling a voltage applied to a load.

[0002]

2. Description of the Related Art In a conventional inverter device, an AC voltage is once converted into a DC voltage and converted into a pseudo AC voltage by PWM control. This conventional inverter device is shown in FIG. 18 and FIG.
This will be described with reference to FIGS.

In FIG. 18, an AC voltage of the commercial power supply 1 is rectified by a rectifying circuit 2 such as a diode bridge, and is once converted into a DC voltage by a smoothing circuit 17 such as an electrolytic capacitor which constitutes a smoothing circuit. This DC voltage is input to the inverter unit 3 having four switching transistors 4a to 4d, which are power transistors and the like, of a full bridge type.
Reference numeral 16 is a reactor for improving the power factor. 5
a, 5b, 5c, and 5d relax the high voltage generated in both main windings 6a through the power supply line 100 and the ground line 101 when the current flowing in the main winding 6a as a load is suddenly stopped. It is a freewheel diode for.

The main controller 9 generates a PWM signal. PW
The inverter driving means 12 turns on / off each of the switching transistors 4a, 4b, 4c, 4d in accordance with the M signal, and converts the DC voltage input to the inverter unit 3 into a pseudo AC voltage. This pseudo AC voltage is applied to the single-phase induction motor 6
Is applied to Specifically, when the switching transistors 4b and 4c are off, the switching transistor 4a is
And PWM control of 4d and switching transistor 4
When a and 4d are off, the switching transistors 4b and 4c are PWM-controlled.

This situation will be described with reference to the signal waveform diagram shown in FIG. 19. The inverter input voltage Vin is the power supply line 100.
Is a rectified DC voltage that is input to the inverter unit 3 through the switching drive signals Va to Vd that turn on / off the switching transistors 4a to 4d.
It is a WM signal. Switching drive signals Va-V
d is a switching transistor 4a-4 at a high level
d is turned on, and vice versa. In the period K1, since both Vb and Vc are at the low level, the switching transistors 4b and 4c are turned off. on the other hand,
Va and Vd are PWM waveforms, and turn on / off the switching transistors 4a and 4d. In the next period K2, the relationship between Va, Vd and Vb, Vc is reversed, the switching transistors 4a, 4d are in the off state, and the switching transistors 4b, 4c are in the on / off controlled state.

The induction motor application signal VM is generated by such a switching pattern, and the single-phase induction motor 6 is generated.
Is applied to The effective voltage VT of the induction motor applied signal VM has a sinusoidal curve and is a pseudo AC voltage. This pseudo AC voltage changes the waveform of the PWM signal for each period K as shown in FIG.
This is realized by making the pulse wide at the center of 1 and K2 and narrow on both sides. By changing the frequency of this pseudo AC voltage, the single-phase induction motor 6
Is controlled.

[0007]

However, the smoothing circuit 17 requires a large-capacity capacitor such as an electrolytic capacitor in order to reduce ripples. This has caused a cost increase. Further, when the capacity of the capacitor becomes large, the input current flows in a peak shape as the capacitor is charged. As a result, the reduction of the power factor and the harmonics of the power supply become a problem, and the maximum rating of parts such as capacitors and switching elements must be increased.

Although the reactor 16 is inserted in the circuit in order to improve the power factor, the cost is increased. Furthermore, a circuit such as an active filter is required to prevent power supply harmonics, which makes the circuit complicated and expensive. Thus, in the above-mentioned conventional example, the AC voltage is once converted into the DC voltage,
Since the pseudo AC voltage is generated by the PWM control, the effective value component of the fundamental wave effective for driving the single-phase induction motor 6 is insufficient. In order to improve this, there is a method of using the rectifier circuit 4 as a voltage doubler rectifier circuit, but this also causes a cost increase.

Further, the pulse width changing P as described above is used.
In order to generate a WM signal, it is necessary to compare a sine wave having a target frequency with a high frequency triangular wave that is a carrier. When the sine wave is larger than the triangular wave, the high level is set, and when the sine wave is smaller than the triangular wave, the low level is set to generate the PWM signal. In order to make such a comparison, the main controller 9
The microcomputer used in the above had to be highly functional.

Since the inverter section 3 generates a pseudo AC voltage to drive the single-phase induction motor 6, only a rectangular wave can be applied to the single-phase induction motor 6 even at the maximum output, and the commercial power source is used. Only about 70% of the AC voltage of 1 was available. Therefore, when a large torque is required such as at the time of starting, the torque is insufficient.

In an inductive load including an inductance like the single-phase induction motor 6, the PWM signal or the main winding 6 is used.
When the four switching transistors are all turned off by stopping the single-phase induction motor 6 in a, the current that has been flowing up to that point (current flowing in the G direction in the figure) is about to be cut. The counter electromotive force that causes the current to continue to flow is generated and the regenerative current i is flowing through the freewheel diodes 5b and 5d. When the current flowing through the main winding 6a flows in the direction opposite to the G direction when the four switching transistors 4a to 4d are turned off, the regenerative current flows via the freewheel diodes 5a and 5c. It goes without saying that is flowing. In addition, the voltage of the power supply line suddenly rises due to the regenerative current i, and there is a fear that the rectifying element such as the switching transistor or the diode in the rectifying circuit 2 is destroyed.
For this reason, it is necessary to increase the maximum rating of the element, resulting in an increase in cost.

In addition to the inverter device, there is a phase control system (not shown) that uses a switching element such as a thyristor or a triac to simply control the single-phase induction motor. In this phase control method, for example, a single-phase induction motor and a triac are connected in series, an AC voltage is applied to this, and a triac is turned on by transmitting a gate signal to the triac after a predetermined time has passed from the zero-cross point. It controls the voltage applied to the single-phase induction motor.

By adjusting the gate signal, the time for which the AC voltage waveform is cut is changed to control the voltage applied to the single-phase induction motor. When the temporary voltage changes, the rotation speed-torque characteristic of the single-phase induction motor changes, and the rotation speed of the single-phase induction motor changes. However, in the phase control method, in the variable speed control of the single-phase induction motor, the voltage waveform is applied to the single-phase induction motor with a large distortion because the voltage is controlled by cutting a part of the AC voltage.

Due to this waveform distortion, the power factor of the single-phase induction motor is greatly reduced. Since the power factor decreases, the current flowing through the single-phase induction motor increases, and the maximum rating of the thyristor, triac, etc. for performing phase control must be increased. As a result, the cost was increased.

In particular, when the voltage applied to the single-phase induction motor is lowered, the cut portion becomes large and the distortion becomes large. Therefore, it becomes difficult to obtain the effective component of the fundamental wave effective for the single-phase induction motor, and the controllable voltage range is narrowed.

As described above, the conventional inverter device and the device using the phase control method have the above-mentioned problems, but also have various other problems. For example, the conventional inverter device has a problem that vibration and noise are generally large.

Further, since the number of times of switching of the switching transistor is relatively large, the number of times of switching is large.
The loss increased and the efficiency decreased. It was also a cause of noise such as noise terminal voltage and unnecessary radiation.

When the single-phase induction motor is stopped, the brake cannot be applied only by turning off the four full-bridge type switching transistors, so that it cannot be stopped rapidly. On the other hand, in a phase control type device using a triac or the like, when a brake is applied, it is necessary to newly provide another switching element for the brake.

Further, in order to obtain a target rotation speed in the single-phase induction motor, a circuit for detecting the rotation speed is separately provided, and feedback control is performed according to the detected rotation speed. With such control, the rotation speed can be kept constant even if the input voltage fluctuates, but parts such as a pilot generator and a hall element are required to detect the rotation speed, which makes the device expensive. It was

When the frequency of the power source is 50 Hz or 60 Hz, the pulley ratio of the single-phase induction motor is changed so that a desired rotation speed can be obtained. Two types of pulleys, 50 Hz and 60 Hz, are provided. Was needed.

The present invention solves these problems.
To provide an inverter device that is inexpensive, efficient, suppresses vibration, noise and noise, prevents element destruction, expands the control range, and can increase the torque when starting the induction motor. With the goal.

[0022]

In order to achieve the above object, in the first structure of the present invention, the first and second switching elements connected in series between the power supply line and the ground line and the power supply are also provided. A third and a fourth switching element connected in series between a line and a ground line, a connection midpoint between the first and second switching elements, and the third,
One of the first and fourth switching elements is turned on and the other is turned on or on with the load connected between the connection midpoints of the fourth switching element and the second and third switching elements being off. A first mode for controlling ON / OFF, and a second mode in which the first and fourth switching elements are OFF.
In an inverter device including an inverter control means having a second mode for controlling one of the third switching elements to be turned on and the other to be turned on or off, the rectifying means rectifies an alternating voltage from a commercial power source, and the rectifying means Means for applying the rectified waveform voltage to the power supply line are provided.

In such a configuration, the AC voltage of the commercial power supply is applied to the power supply line in the form of an unsmoothed rectified waveform voltage. In the first mode, current flows through the load in the route of power supply line → first switching element → load → fourth switching element → ground line. Further, in the second mode, the power supply line → the third switching element → the load → the second
Current flows to the load through the switching element → ground line path. In each of these modes, the voltage applied to the load is the voltage of the power supply line (rectified waveform voltage) chopped in pulses. Moreover, in the first mode and the second mode, the voltage applied to the load is in the opposite direction, so that it becomes a pseudo AC voltage as a whole. At this time, for example, if the first and second modes are switched by starting at the zero-cross of the AC voltage of the commercial power supply, the pseudo AC voltage becomes sinusoidal. The effective voltage of the pseudo AC voltage applied to the load is controlled by adjusting the ON / OFF duration of the switching element in each of the first mode and the second mode.

Further, in the second configuration of the present invention, in the first configuration, the load is an inductive load, and in the first mode, the first switching element is PWM-controlled to perform the fourth configuration. The switching element is turned on, and in the second mode, the third switching element is PWM-controlled to turn on the second switching element.

In such a configuration, the rectified waveform voltage which is not smoothed on the power supply line is generated by the switching element PW.
When M is controlled, it is chopped and becomes a pseudo AC voltage. At this time, the effective voltage applied to the inductive load is controlled by changing the duty ratio of the PWM signal. PW
Since M control is performed only for one switching element in each mode, there is no risk of on / off synchronization deviation and the number of times of switching is reduced as compared with the case where it is performed for two switching elements. To do.

Further, in a third structure of the present invention, in the first structure or the second structure, there is a detecting means for detecting a zero-cross point of the AC voltage, and the inverter control means is the zero-cross point. The first mode and the second mode are switched in synchronism with the above.

In such a configuration, the first mode and the second mode are switched in synchronization with the zero-cross point of the AC voltage, and the pseudo sine wave is applied to the inductive load.

Further, in a fourth configuration of the present invention, in the above second configuration, the inductive load is an induction motor, and when the brake is applied, the induction load is fixed to one of the first and second modes and Instead of the PWM signal, a DC voltage is applied to the switching element.

In such a configuration, when the induction motor is braked, the rectified waveform voltage is applied to the induction motor as it is without being chopped. When the rectified waveform voltage is applied to the winding of the induction motor, the magnetic poles of the winding are fixed, so that the rotor of the induction motor is braked and the induction motor is suddenly stopped.

Further, in the fifth configuration of the present invention, in the second configuration, a freewheel diode is connected in parallel to any of the first to fourth switching elements.

In such a configuration, the first mode, the second mode
In each of the above modes, when the PWM controlled switching element is turned off, the first and third power line side
Since the switching elements are both turned off, the counter electromotive force of the inductive load is generated. Since the regenerative current flows back to the ground line through the diode and the switching element and is attenuated, it does not flow into the rectifying means and prevents the voltage of the power supply line from rising sharply. Further, when the power of the inverter device is turned off, all the first to fourth switching elements are turned off. At this time, the regenerative current due to the counter electromotive force generated in the inductive load causes the diode on the ground line side and the power line side to Although it is circulated to the power supply line by the diode, there is no problem because the inverter device is put into an unused state when the power supply is cut off.

Further, in a sixth structure of the present invention, in the third structure, a freewheel diode is connected in parallel to any of the first to fourth switching elements, and the inductive load is stopped. In the period, the first,
The third switching element is turned off and the second and fourth switching elements are turned on.

In such a configuration, the regenerative current generated after the operation of the inductive load is stopped is circulated in either direction by either the second or fourth switching element or the ground line side diode. And decay. This regenerative current does not flow into the rectifying means and prevents the voltage of the power supply line from rising sharply to prevent damage to the element. The operation when the power of the inverter device is turned off is the same as in the case of the fifth configuration.

Further, in a seventh configuration of the present invention, in the second configuration, there is provided a detecting means for detecting a zero-cross point of the AC voltage, and the first and the second are provided for a predetermined period including the zero-cross point. The switching element PWM-controlled in the second mode is turned off, and the first and second modes are switched.

In such a configuration, the PWM-controlled switching element is turned off for a predetermined period including the zero-cross point. A zero-cross point is detected during that period, and the first and second modes are switched in synchronization with the AC voltage. PWM control is started after a lapse of a predetermined period. No voltage is applied to the inductive load for a predetermined period including the zero-cross point.

In the inductive load, there is a phase difference between the voltage and the current applied to the inductive load. Therefore, in the vicinity of the zero-cross point of the AC voltage, there is a period in which the direction of the applied voltage and the direction of the current are opposite. Even if PWM control is performed during this period, it is not very effective. It is possible to omit such PWM control that does not function effectively. Further, it is possible to prevent the power supply line and the ground line from being short-circuited when switching between the first and second modes.

Further, in the eighth structure of the present invention, in the second structure, there is provided means for detecting the amplitude of the AC voltage, and the duty ratio of the PWM signal is changed based on the amplitude of the AC voltage. Provide means.

In such a configuration, the duty ratio is changed according to the amplitude of the detected AC voltage. If the amplitude of the AC voltage increases, the duty ratio is decreased, and conversely, if the amplitude decreases, the duty ratio is increased to keep the effective voltage of the voltage applied to the load constant. As a result, the load is not affected by fluctuations in the amplitude of the AC voltage.

Further, in a ninth configuration of the present invention, in the first configuration, the load is an induction motor, has means for detecting the frequency of the AC voltage, and based on the frequency of the AC voltage, A means for changing the duty ratio of the PWM signal is provided.

In such a configuration, it is detected whether the frequency of the AC voltage is 50 Hz or 60 Hz. When the frequency is 60 Hz, the duty ratio of the PWM signal is reduced to reduce the effective voltage applied to the induction motor.
The rotation speed of the induction motor increases as the frequency increases, but by reducing the effective voltage, the rotation speed is suppressed and a constant rotation speed can be obtained regardless of the frequency of the AC voltage.

In the tenth structure of the present invention, the above-mentioned fourth structure is used.
In the above configuration or the ninth configuration, when the induction motor is started, a DC voltage is applied to the switching element instead of the PWM signal.

In such a configuration, since a DC voltage is applied to the switching element at the time of start-up, the rectified waveform voltage is not chopped and is converted to AC with the waveform left and applied to the induction motor. . The induction motor can output the maximum torque by the AC voltage that is the basic component of the commercial power supply, and starts rapidly. After a while, the switching element has PWM instead of DC voltage.
A signal is given and the induction motor is quickly controlled to the target rotation speed.

Further, in the eleventh structure of the present invention, it has a power supply line, a load, and a switching element, and controls the switching element to be turned on / off to supply power from the power supply line to the load. In the above inverter device, the rectified waveform voltage from the rectifying means for rectifying the AC voltage of the commercial power supply is input to the power supply line.

In such a configuration, the AC voltage of the commercial power source is rectified by the rectifying means. The rectified waveform voltage is input to the power supply line. Switching element is on /
By being off-controlled, the voltage of the power supply line is chopped. The voltage applied to the load is controlled. By controlling the on / off period, the appropriate voltage is applied to the load.

Further, in the twelfth structure of the present invention, the first structure
In the configuration of No. 1, the rectifying means rectifies the AC voltage into a full-wave rectified waveform voltage.

In such a configuration, the AC voltage from the commercial power source is rectified into the full-wave rectified waveform voltage by the rectifying means,
It is transmitted to the power line. By controlling the ON / OFF of the switching element, the full-wave rectified waveform voltage is converted into an appropriate voltage and applied to the load.

In addition, in a thirteenth structure of the present invention, the above first
In the configuration of No. 1, the rectifying means rectifies the AC voltage into a half-wave rectified waveform voltage.

In such a configuration, the AC voltage from the commercial power source is rectified by the rectifying means into a half-wave rectified waveform voltage,
It is transmitted to the power line. By controlling ON / OFF of the switching element, the half-wave rectified waveform voltage is converted into an appropriate voltage and applied to the load.

In the fourteenth structure of the present invention, the first structure
In the first configuration, the rectifying means is provided with a capacitor, and the AC voltage is rectified into a pulsating rectified waveform voltage.

In such a structure, the voltage rectified by the rectifying means is smoothed by the capacitor. However, since the electric capacity of the capacitor is small, it is not completely smoothed and becomes a pulsating current rectified waveform voltage. By controlling ON / OFF of the switching element, the rectified waveform voltage is converted into an appropriate voltage and applied to the load.

In the fifteenth aspect of the present invention, the first
In the configuration of No. 1, two switching elements are connected in series. In such a configuration, a voltage is applied to the load from one direction, and the voltage applied to the load is controlled by on / off control.

Further, in the sixteenth constitution of the present invention, the first constitution
In the configuration of 1, the four switching elements are connected in a full bridge type. In such a configuration, four switching elements are connected in a full bridge type,
An alternating voltage can be applied to the load. The voltage applied to the load is controlled by controlling ON / OFF of the switching element.

In the seventeenth constitution of the present invention, the first constitution
In the configuration of No. 1, the switching element is controlled based on the zero cross point of the AC voltage. In such a configuration, the switching element switches the switching pattern at the zero-cross point of the AC voltage, and the voltage applied to the load is synchronized with the frequency of the commercial power source.

[0054]

BEST MODE FOR CARRYING OUT THE INVENTION

<First Embodiment> A first embodiment of the present invention will be described with reference to FIGS. 1, 2, and 3. FIG. 1 is a control block diagram showing a first embodiment of an inverter device of the present invention. The AC voltage of the commercial power source 1 is full-wave rectified by a rectifier circuit 2 such as a diode bridge, and four switching transistors 4a, 4b, 4c, 4d such as power transistors and four free wheel diodes 5a, 5b, 5c, 5
It is input through the power supply line 100 to the inverter unit 3 in which d is a full bridge type. As can be seen from the comparison with FIG. 18, the smoothing circuit 17 is omitted in this embodiment. Therefore, the rectified waveform voltage output from the rectifier circuit 2 is applied to the inverter unit 3 as it is (in a pulsating flow) without being converted into a direct current. Along with this, the reactor 16 for improving the power factor is also unnecessary.

The midpoints of the switching transistors 4a and 4b and the midpoints of the switching transistors 4c and 4d are connected to the single-phase induction motor 6. The single-phase induction motor 6 has a main winding 6a and an auxiliary winding 6b, and a capacitor 7 is connected in series to the auxiliary winding 6b. When an AC voltage is applied to the single-phase induction motor 6, a rotating magnetic field is generated by the main winding 6a and the auxiliary winding 6b to rotate a rotor (not shown).

The rotation speed is determined by the frequency of the AC voltage applied to the single-phase induction motor 6. Even if the amplitude of the applied AC voltage changes, the single-phase induction motor 6
The rotation speed-torque characteristic of changes the rotation speed.

The power supply frequency detection means 8 detects the zero-cross point of the AC voltage of the commercial power supply 1 and sends it to the main control means 9.
The main control unit 9 determines the duty ratio of the switching pattern based on the signal indicating the target rotation speed from the rotation speed setting unit 10. The PWM control means 11 creates a PWM signal for switching the switching transistors 4a, 4b, 4c, and 4d from the information of the zero-cross point and the duty ratio from the main control unit 9. The inverter driving means 12 switches the switching transistors 4a, 4b, 4c and 4d based on the PWM signal.

Next, the switching pattern by the switching drive signals Va to Vd will be described with reference to FIG. The full-wave rectified waveform voltage input to the inverter unit 3 is only rectified by the diode bridge 2 of the commercial power supply 1 and is not smoothed by the smoothing circuit 17 (see FIG. 18) such as a capacitor, so that a complete DC voltage waveform is obtained. However, it has a pulsating full-wave rectified waveform. This voltage waveform is used as the input voltage Vin of the inverter unit 3.

The switching drive signals Va, Vb, Vc,
Vd is the switching transistors 4a, 4b,
This is a signal for turning on / off 4c and 4d. The switching transistors 4a, 4b, 4c, and 4d are turned on when the switching drive signals Va, Vb, Vc, and Vd are at a high level, and are turned off when they are at a low level.

In the first mode, the switching transistor 4a turns on / off according to the drive signal Va. At that time, the switching transistor 4d continues to be turned on because the drive signal Vd is at the high level. During this time, the switching transistors 4b and 4c are in the off state because Vb and Vc are both at the low level. As a result, the positive-direction induction motor application signal VM is given to the single-phase induction motor 6.

When the power supply frequency detection means 8 detects the zero-cross point of the AC voltage, the PWM control means 11 switches from the first mode to the second mode. In the second mode, Va and Vd become low level and the switching transistor 4
a, 4d are turned off, and the switching transistor 4c is set to P
ON / OFF control is performed by the WM signal Vc. At this time, the switching transistor 4b continues to be turned on by the high level Vb. As a result, the negative direction induction motor application signal VM is given.

When the zero cross point of the AC voltage is detected again, the switching pattern is returned to the original pattern, and the above switching is repeated thereafter. First, the first mode is set in the period T1, the second mode is set in the period T2, and the first mode is set again in the period T3. Thus, the first
The mode and the second mode are alternately repeated. In addition, PWM
The signal has a constant frequency of several kHz or more, and only its duty ratio (on / off ratio) changes. However, the PWM signal shown in FIG. 2 has a constant duty ratio. On the other hand, in FIG. 9 described later, the input voltage Vi
The duty ratio is changed according to the magnitude of n, and in FIG. 10, the duty ratio is changed according to the frequency of the input voltage Vin. However, in the case of these FIG. 9 and FIG.
For only one period, the duty ratio is constant,
The conventional duty ratio change is not performed.

In the voltage waveform applied to the single-phase induction motor 6 by such switching, since the inverter input voltage Vin has a pulsating shape, the pulse is PAM-modulated, and the induction motor application signal VM. It becomes a pseudo sine wave as shown in. The effective voltage VT actually applied to the single-phase induction motor 6 has a sinusoidal curve.

For example, a duty ratio of 50% (ON 50%,
When the commercial power supply 1 is AC 100V (effective value) in the case of OFF 50%), the effective voltage is 50V. By controlling the duty ratio in this way, the amplitude of the voltage applied to the single-phase induction motor 6 is controlled. Since the rotation speed-torque characteristic of the single-phase induction motor 6 changes depending on the applied primary voltage, the rotation speed changes by controlling the voltage applied to the single-phase induction motor 6. By varying the duty ratio in this way, the rotation speed of the single-phase induction motor 6 is controlled to the target rotation speed set by the rotation speed setting means 10.

By the way, in the first mode, the switching transistor 4a is on / off controlled by the PWM signal. When the switching transistor 4a is switched from on to off, the current flowing in the G direction in FIG. 3 is cut, and a counter electromotive force is generated. At this time, in the present embodiment, since the switching transistor 4d is in the ON state, the regenerative current A due to the counter electromotive force causes the free wheel diode 5b, the electric motor 6,
It is returned to the ground line 101 side through the switching transistor 4d. Regenerative current A is power line 100
Since it does not flow to the power line, it prevents the voltage of the power supply line from rising sharply.

On the other hand, in the second mode, the switching transistor 4c is on / off controlled. When the switching transistor 4c is switched from on to off, the regenerative current B flows in the direction opposite to the G direction. Since the switching transistor 4b is in the ON state, the regenerative current B is returned to the ground line 101 side through the freewheel diode 5d, the electric motor 6, and the switching transistor 4b. The regenerative current B does not flow in the power supply line 100. The voltage of the power supply line 100 is prevented from rapidly increasing, and the switching transistors 4a to 4d and the elements such as the diodes in the rectifier circuit 2 are prevented from being destroyed. When the power of the inverter device is turned off, the switching transistors 4a, 4b, 4c and 4d are simultaneously turned off. The high voltage generated at both ends of the main winding 6a is mitigated by the diodes 5a to 5d as in the conventional inverter device.

As described above, the smoothing circuit 17 is used in this embodiment.
Power line 1 (see Figure 18) has been deleted
The current does not flow in the peak state at 00, and the reduction of the power factor and the harmonics of the power source are prevented. The induction motor applied signal VM contains many AC fundamental wave components, and the efficiency is improved. Even when the control voltage is in the low voltage region, the distortion of the waveform is small, so that the voltage can be controlled. Since there is only one switching transistor 4a to 4d controlled by the PWM signal in each mode, the number of times of switching can be reduced. This suppresses noise such as noise terminal voltage and unnecessary radiation.

Further, the switching transistor is an IGBT.
If a MOS-FET is used, the frequency of the PWM signal can be set to several tens of kHz or higher, and the audible frequency or higher can be achieved to reduce noise.

<Second Embodiment> A second embodiment of the present invention will be described with reference to FIGS. In FIGS. 4 and 5, the same parts as those in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted. In FIG. 4, braking means 13 is provided to brake the single-phase induction motor 6 to bring it to a sudden stop. In FIG. 5, the switching transistor 4a
Is turned on / off by the PWM signal, and the braking is started at time t0 from the state in which the single-phase induction motor 6 is controlled in the period T1. Braking is performed in the periods T2 and T3.

As shown in FIG. 5, when the brake is applied from the end of the first mode (in this case, the period of T1), Va and Vd are set to the high level during the periods of T2 and T3, and the switching element 4a. 4d turned on, Vb, Vc
To the low level and the switching transistors 4b and 4
c is turned off. As a result, the induction motor application signal VM becomes a positive pulsating flow DC voltage like the inverter input voltage Vin.

When this DC voltage is applied to the single-phase induction motor 6, the current j is changed to the switching transistors 4a and 4d.
Through the main winding 6a in the G direction. for that reason,
The main winding 6a serves as an electromagnet with fixed magnetic poles, and brakes a rotor (not shown) of the single-phase induction motor 6. In this way, the single-phase induction motor 6 can be stopped suddenly.

However, if this state is continued for a long time, the temperature of the main winding 6a rises due to the current j. Therefore, it is appropriate depending on the inertia (ease of stopping) of the single-phase induction motor 6 and the braking performance. Change the time to apply DC voltage to
Stop braking.

On the other hand, when the brake is applied from the second mode, the switching transistors 4a and 4d are turned off and the switching transistors 4b and 4c are turned on. As a result, current flows through the switching transistors 4b and 4c in the main winding 6a in the direction opposite to the G direction. As a result, the single-phase induction motor 6 is similarly stopped suddenly.

If a DC voltage is applied to the single-phase induction motor 6, the brake is applied. Therefore, even if the switching transistor is not turned on for the entire braking time, the temperature rise of the switching transistor and For example, due to improvement in braking performance, the switching transistor may be turned on or off in a pulsed manner.

<Third Embodiment> A third embodiment of the present invention will be described with reference to FIGS. In FIG. 6, the same parts as those in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted. In the third embodiment, during the stop period of the single-phase induction motor 6, the switching transistors 4a and 4c are turned off and the switching transistors 4b and 4d are turned on. In the periods T1 and T2, the state in which the single-phase induction motor 6 is driven by the PWM control is stopped at the time t0. Period T3
Is the suspension period.

Time t at which the second mode of period T2 ends
When switching is stopped at 0, the switching transistor 4
a, 4c are turned off, and switching transistors 4b, 4
d turns on. At this time, a counter electromotive force is generated in the opposite direction to G. In this case, the regenerative current B returns to the ground line 101 side through the free wheel diode 5d and the switching transistor 4b. Since the regenerative current B is gradually attenuated, the regenerative current B does not return to the power supply line 100, and the element is prevented from being broken. When the single-phase induction motor 6 is stopped at the time when the first mode ends, a counter electromotive force is generated in the G direction, but the regenerative current A passes through the freewheel diode 5b and the switching transistor 4d and the ground line. Reflux on side 101.

<Fourth Embodiment> A fourth embodiment of the present invention will be described with reference to FIG. In FIG. 7, the same parts as those in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted. Near the zero-cross point of the AC voltage of the commercial power source 1 (see Fig. 1),
The PWM signal is masked at a predetermined time from t1 to t2 so as to include the zero-cross point. Va and Vc in the mask period
Is set to a low level to turn off both of the switching transistors 4a and 4c which are turned on / off by the PWM signal.

The switching transistors 4b and 4d are turned on / off in accordance with the zero cross point of the mask period. For example, in the mask periods t1 to t2, Vb is changed from a low level to a high level, and Vd is changed from a high level to a low level to turn on the transistor 4b, turn off the transistor 4d, and the next mask period t1 ′ to At t2 ′, the transistor 4b is turned off and the transistor 4d is turned off by changing Vb from high level to low level and changing Vd from low level to high level. Therefore, during the mask periods t1 to t2 and t1 'to t2', the transistors 4b and 4 are
d has been turned on alternately, but transistor 4
Since a and 4c are both off, no voltage is applied to the induction motor 6 (see VM in FIG. 7). When the mask period becomes longer, the effective voltage of the induction motor applied signal VM decreases, but the frequency of the commercial power source 1 (see FIG. 1) becomes 5
Since it is 0 Hz or 60 Hz, if the mask period is 1 millisecond or less, it will be the valley portion of the inverter input voltage Vin, so there is little effect.

Since there is a phase difference between the applied voltage and current in an inductive load such as the single-phase induction motor 6 (see FIG. 1), switching 4a and 4c (see FIG. 1) are performed in this mask period.
Even if the switching is rapidly performed, the direction of the applied voltage and the direction of the current are reversed, and the switching effect by the PWM control is not so effective. In this embodiment, unnecessary switching is omitted by not performing PWM switching during the mask period.

When the mask period is not provided, at the zero-cross point of the AC voltage, if the switching transistors 4b and 4d (see FIG. 1) are turned on / off, the switching transistors 4a and 4b are switched.
If the on / off switching of (see FIG. 1) is delayed, the power supply line 100 and the ground line 101 may be short-circuited and the switching transistors 4a to 4d may be destroyed.
00 and the ground line 101 are prevented from being short-circuited. Thereby, the switching transistors 4a-4
The destruction of d is prevented.

<Fifth Embodiment> A fifth embodiment of the present invention will be described with reference to FIGS. 8 and 9. 8 and 9, the same parts as those in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted. In the present embodiment, the input voltage detection means 14 for detecting the AC voltage of the commercial power supply 1 is provided to detect the amplitude of the AC voltage. Incidentally, 15a and 15b are resistors for taking in a voltage proportional to the AC voltage to the input voltage detecting means 14.

Based on the detected amplitude, the main controller 9
When the voltage is large, PWM as shown in FIG.
When the duty ratio of the signal is lowered and the input voltage is large, the PWM control means 11 is controlled so as to raise the duty ratio as shown in FIG. 9B. As a result, the effective voltage VT applied to the single-phase induction motor 6 is kept constant regardless of the magnitude of the input voltage.

According to the present embodiment, even if the input voltage changes, the primary voltage applied to the single-phase induction motor 6 becomes constant, the rotation speed does not change, and there is an advantage of being stable.
Accordingly, it is not necessary to provide a rotation speed detecting means such as a pilot generator or a hall element for keeping the rotation speed constant.

<Sixth Embodiment> A sixth embodiment of the present invention will be described with reference to FIG. In addition, in FIG.
The same parts as those in FIG. Whether the frequency of the commercial power source 1 (see FIG. 1) is 50 Hz or 60 H by the power source frequency detecting means 8 (see FIG. 1)
It is detected whether it is z. When the frequency is 60 Hz, the duty ratio of the PWM signal is lowered to lower the effective voltage VT applied to the single-phase induction motor 6 (see FIG. 1).

In the single-phase induction motor 6 (see FIG. 1), when the frequency is 60 Hz, the synchronous rotation speed due to the rotating magnetic field becomes faster when the frequency is 60 Hz, and when the same voltage is applied,
The rotation speed becomes faster when the frequency is 60 Hz. 60Hz
By lowering the duty ratio of the PWM signal at this time, the voltage applied to the single-phase induction motor 6 (see FIG. 1) is lowered, thereby obtaining the same rotation speed as in the case of the frequency of 50 Hz. As a result, the electric motor 6 can be rotated at the same rotation speed regardless of whether the frequency is 50 Hz or 60 Hz.

<Seventh Embodiment> A seventh embodiment of the present invention will be described with reference to FIG. In addition, in FIG.
The same parts as those in FIG. Single-phase induction motor 6 at time t0 (see FIG. 1)
Is started. In the periods T1 and T2, the single-phase induction motor 6
On / off control of the switching transistors 4a and 4c (see FIG. 1) is performed at a duty ratio of 100% so that the torque (see FIG. 1) becomes large.

In this way, the induction motor applied voltage V
A sine wave voltage similar to the input voltage is obtained at M. Since the induction motor applied signal VM includes only the fundamental wave component of the input voltage, the efficiency is high and the maximum output torque is obtained. When the single-phase induction motor 6 (see FIG. 1) starts up,
Since the torque may be small, the time T
At 3 and T4, the PWM control is performed by changing the duty ratio so as to achieve the target rotation speed.

As a result, the torque shortage at the time of start-up is resolved, and problems such as inability to start up are solved. The time required for startup is also reduced. Further, the duty ratio may be switched from 100% to the target duty ratio at a time, but the duty ratio may be changed stepwise so as to be closer to the target value.

<Eighth Embodiment> An eighth embodiment of the present invention will be described with reference to FIGS. 12 and 13. Incidentally, FIG.
13, the same parts as those in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted. A rectifier circuit 2 composed of a diode is inserted in the power supply line to half-wave rectify the AC voltage of the commercial power supply 1.

In FIG. 13, in the period T1, the inverter input voltage Vin becomes a half-wave rectified positive voltage. The switching drive signal Va has a PWM waveform, and the switching transistor 4a is on / off controlled. The switching transistors 4b and 4c are turned off and the switching transistor 4d is turned on. The induction motor applied signal VM is generated by such a switching pattern. In the period T2, no voltage is applied to the inverter input voltage Vin. The switching drive signal Va is set to low level to turn off the switching transistor 4a. Therefore, since the signal VM is not given to the electric motor 6 in the period T2, the electric motor 6 only rotates by inertia during this period.

In the period T3, the switching drive signal Vc
Is used as a PWM waveform to control on / off of the switching transistor 4c. Switching transistors 4a, 4
d is turned off, and the switching transistor 4b is turned on. Switching is switched in synchronization with the voltage of the half-wave rectified waveform. The effective voltage VT of the induction motor application signal VM generated by such switching is half the frequency of the commercial power supply 1. In the eighth embodiment, there are intermittent periods when the drive signal VM is not applied to the electric motor 6, so that the torque is reduced by that amount, but the functions of the rectifier circuit 2 and the like are simplified. This embodiment is effective for the low torque electric motor 6.

<Ninth Embodiment> A ninth embodiment of the present invention will be described with reference to FIGS. 14 and 15. Incidentally, FIG.
15, the same parts as those in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted. The AC voltage of the commercial power source 1 is full-wave rectified by the rectifier circuit 2 and smoothed by a normal capacitor 18 having a small electric capacity such as a film capacitor.

However, since the electric capacity of the capacitor 18 is small, the capacitor 18 is not completely smoothed and has a pulsating rectified waveform voltage like the inverter input voltage Vin shown in FIG. Then, switching is performed by the switching drive signals Va to Vd to generate the induction motor application signal VM.
The effective voltage VT has a sinusoidal curve. In this embodiment, the duty ratio is reduced at the end of each period T1, T2, T3, ... Or by providing a mask period as in the fourth embodiment shown in FIG. The small part of may be deleted.

<Tenth Embodiment> A tenth embodiment of the present invention will be described with reference to FIGS. FIG.
6. In FIG. 17, the same parts as those in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted. The load 19 is a load, such as a light bulb, a fluorescent lamp, or an electric heater, which operates even when a voltage is applied in one direction. The applied voltage setting means 20 sets the voltage applied to the load 19.

The switching drive signal Va shown in FIG.
The applied signal VM is generated in DC by Vd, and the load 19
Is applied to The effective voltage VT is controlled by changing the duty ratio.

The first to tenth embodiments can be realized by combining a plurality of them. A two-phase induction motor can also be used instead of the single-phase induction motor 6 (see FIG. 1).

[0097]

【The invention's effect】

<Effect of claim 1> In the present invention, smoothing such that the voltage after rectification becomes a constant value need not be performed, so a large-capacity capacitor such as that of a conventional inverter device need not be used. Therefore, the cost of the device is reduced. Further, there is no problem that a peak current flows through the power supply line when the capacitor is charged. Therefore, the power factor is improved and the power supply harmonics are suppressed. As a result, it is not necessary to connect a separate component such as a reactor for improving the power factor or an active filter as a countermeasure for power source harmonics, and the cost can be reduced from this point as well. Furthermore, the improved efficiency suppresses the value of the current flowing through the switching element, so that the one with a smaller maximum rating can be used. This also leads to cost reduction. Further, since the unrectified rectified waveform voltage is chopped by turning on / off the switching element and the alternating voltage generated thereby is applied to the load, the effective value component of the fundamental wave effective for the load is Increased, the efficiency of load driving has improved.

<Effect of Claim 2> PWM control is performed only for one switching element in each mode.
The number of times of switching is reduced as compared with the case where it is performed for each switching element. Further, there is no fear of on / off synchronization deviation. As a result, the efficiency of the inverter device is improved and the power consumption can be reduced. Also, noise such as noise terminal voltage and unnecessary radiation is reduced. In addition, since a complicated PWM signal used in the conventional inverter device (a PWM signal that changes such that the duty ratio is large at the center of each mode period and small at the end) is not used, The effect is that the microcomputer does not have to have a high function.

<Effect of Claim 3> The pseudo AC voltage applied to the load has a sine wave shape, so that the load is smoothly driven and the efficiency is improved. This is simple because it is only necessary to detect the zero-cross of the AC voltage of the commercial power source for controlling the mode switching.

<Effect of Claim 4> When the brake is applied to the induction motor, a current is supplied to the induction motor in one direction. As a result, the main winding of the induction motor becomes an electromagnet whose magnetic poles are fixed and acts as a braking means. Therefore, the brake can be realized without providing another special braking circuit.

<Effect of Claim 5> When the switching element is switched from ON to OFF by the PWM control, the regenerative current flowing by the counter electromotive force flows back through the diode. The regenerative current does not return to the power supply line, and the rise in voltage of the power supply line can be suppressed. As a result, destruction of elements such as switching elements and diodes used in the rectifying means is prevented and reliability is improved. In addition, a small maximum rating can be used, leading to cost reduction.

<Effect of claim 6> The regenerative current generated when the inductive load is stopped causes the second and fourth switching elements on the ground line side to be in the ON state. It flows back through the fourth switching element and is attenuated. Therefore, the voltage of the power supply line is prevented from sharply increasing due to the regenerative current, so that the element is prevented from being broken. Since the maximum rating of the element can be lowered, the cost can be reduced.

<Effect of Claim 7> Since the voltage and current applied to the inductive load have a phase difference, there is a period near the zero cross when the directions of the voltage and the current applied to the inductive load are opposite. Since PWM control does not work effectively during this period, the switching element that is PWM controlled is turned off for a predetermined period. As a result, unnecessary switching due to PWM control is omitted. When the switching element of the first or third switching element is turned on during the predetermined period, when the switching timing of the second and fourth switching elements deviates from the zero cross point, the first and second switching elements. Alternatively, the power supply line and the ground line may be short-circuited by the third and fourth switching elements, but in the invention of this claim, when the mode is switched at the zero-cross point, the second line on the ground line side,
Even if the timing of switching on / off of the fourth switching element is deviated, the first and third switching elements on the power supply line side are in the off state, so that the power supply line and the ground line are not short-circuited and the element is destroyed. To be prevented.

<Effect of Claim 8> Even if the amplitude of the AC voltage of the commercial power source fluctuates, the duty ratio is controlled based on the amplitude. If the amplitude becomes large, the duty ratio becomes small, and if the amplitude becomes small, the duty ratio becomes large. As a result, the effective voltage applied to the load is kept constant. Further, as a result, when the load is an induction motor, feedback control for keeping the rotation speed constant becomes unnecessary. Therefore, it is not necessary to attach a rotation speed detecting means such as a pilot generator or a hall element. Inexpensive control can be performed in response to voltage fluctuations.

<Effect of Claim 9> The frequency of the AC voltage is 5
When 0 Hz or 60 Hz is detected and the frequency is 60 Hz, the duty ratio of the PWM signal is reduced. This reduces the effective voltage applied to the induction motor.
As the induction motor has a higher frequency, the synchronous rotation speed due to the rotating magnetic field increases, so by lowering the effective voltage,
The same rotation speed can be obtained when the frequency is 50 Hz or 60 Hz. Therefore, it is not necessary to change the pulley ratio of the induction motor, and even if the commercial power source is in the 50Hz area,
The same can be used in the Hz area.

<Effect of Claim 10> When a large torque is required such as when the induction motor is started, almost 100% of the commercial power can be applied to the induction motor, and the torque of the induction motor becomes maximum. . Since the sinusoidal voltage is applied to the induction motor instead of the PWM-controlled pseudo AC voltage in the conventional inverter device, the inherent performance of the induction motor can be sufficiently obtained. As a result, it is possible to prevent the induction motor from being unable to start and to start it quickly.

<Effect of Claim 11> The AC voltage from the commercial power source becomes a rectified waveform voltage by the rectifying means. Since a large-capacity capacitor is not used for the rectifying means,
Low cost. This waveform voltage has high efficiency because the effective value component of the fundamental wave effective for the load increases in the voltage applied to the load due to the ON / OFF control of the switching element.

<Effect of Claim 12> Since the voltage applied to the load is generated from the full-wave rectified waveform voltage, the voltage can be continuously applied to the load, and a large output can be obtained.

<Effect of Claim 13> Since electric power is supplied to the load from the half-wave rectified waveform voltage, the voltage is intermittently applied and a large output cannot be obtained, but the rectifying means may rectify only the half-wave. So it will be simple. If the output of the load may be small, an inexpensive inverter device can be realized.

<Effect of Claim 14> Since a capacitor having a small electric capacity is used, the cost does not increase so much. The noise generated on the power line is mitigated by the capacitor so that it does not affect the load.

<Effect of Claim 15> A voltage is applied to the load from one direction, and only the effective voltage value is controlled. If the load operates only by applying a voltage from one direction, the cost is reduced because there are only two switching elements. Moreover, the control can be simplified.

<Effect of Claim 16> Four switching elements are connected in a full bridge type, and an AC voltage can be applied to a load. Control is not too complicated, and it is not necessary to use a high-performance microcomputer.

<Effect of Claim 17> The voltage applied to the load has a wavy shape, the load is smoothly driven, and the efficiency is improved. Since it is only necessary to detect the zero-cross of the AC voltage of the commercial power supply for the mode switching control,
Easy.

[Brief description of drawings]

FIG. 1 is a control block diagram of an inverter device according to a first embodiment of the present invention.

FIG. 2 is a signal waveform diagram thereof.

FIG. 3 is a circuit diagram showing the flow of the regenerative current.

FIG. 4 is a control block diagram of an inverter device according to a second embodiment of the present invention.

FIG. 5 is a signal waveform diagram thereof.

FIG. 6 is a signal waveform diagram of an inverter device according to a third embodiment of the present invention.

FIG. 7 is a signal waveform diagram of an inverter device according to a fourth embodiment of the present invention.

FIG. 8 is a control block diagram of an inverter device according to a fifth embodiment of the present invention.

FIG. 9 is a control block diagram thereof.

FIG. 10 is a signal waveform diagram of an inverter device according to a sixth embodiment of the present invention.

FIG. 11 is a signal waveform diagram of an inverter device according to a seventh embodiment of the present invention.

FIG. 12 is a control block diagram of an inverter device according to an eighth embodiment of the present invention.

FIG. 13 is a signal waveform diagram thereof.

FIG. 14 is a control block diagram of an inverter device according to a ninth embodiment of the present invention.

FIG. 15 is a signal waveform diagram thereof.

FIG. 16 is a control block diagram of an inverter device according to a tenth embodiment of the present invention.

FIG. 17 is a signal waveform diagram thereof.

FIG. 18 is a control block diagram of a conventional inverter device.

FIG. 19 is a signal waveform diagram thereof.

FIG. 20 is a circuit diagram showing the flow of the regenerative current.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Commercial power source 2 Rectifier circuit 3 Inverter section 6 Single-phase induction motor 8 Power supply frequency detection means 9 Main control section 10 Rotation speed setting means 11 PWM control means 12 Inverter drive means 16 Reactor 17 Smoothing circuit 18 Capacitor 19 Load

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H02P 7/63 301 H02P 7/63 301N

Claims (17)

[Claims] 1. A first switching element and a second switching element connected in series between a power supply line and a ground line, and a third switching element and a fourth switching element connected in series between the power supply line and the ground line. , A load connected between the connection midpoints of the first and second switching elements and the connection midpoints of the third and fourth switching elements, and the second,
In the off state of the third switching element, the first and the fourth
A first mode in which one of the switching elements is turned on and the other is turned on or on / off controlled; and one of the second and third switching elements is turned on while the first and fourth switching elements are off. In an inverter device provided with an inverter control means having a second mode for controlling the other on or on / off, the rectifying means rectifies an AC voltage from a commercial power source, and a rectified waveform voltage from the rectifying means is applied to the power supply line. An inverter device comprising means. 2. The load is an inductive load, the first switching element is PWM-controlled in the first mode to turn on the fourth switching element, and the third switching element is in the second mode. 2. The inverter device according to claim 1, wherein the switching element is PWM-controlled to turn on the second switching element. 3. A detection means for detecting a zero-cross point of the AC voltage, wherein the inverter control means switches between the first and second modes in synchronization with the zero-cross point. The inverter device according to claim 1 or claim 2. 4. The induction load is an induction motor, and when a brake is applied, it is fixed to one of the first and second modes and a DC voltage is applied to a switching element instead of a PWM signal. The inverter device according to claim 2. 5. The inverter device according to claim 2, wherein a freewheel diode is connected in parallel to each of the first to fourth switching elements. 6. A freewheel diode is connected in parallel to any of the first to fourth switching elements, and the first and the fourth switching elements are connected in parallel during a stop period of the inductive load.
The inverter device according to claim 3, wherein the third switching element is fixed in an off state and the second and fourth switching elements are fixed in an on state. 7. A detection device for detecting a zero-cross point of the AC voltage, wherein a switching element PWM-controlled in the first and second modes is turned off for a predetermined period including the zero-cross point. The inverter device according to claim 2, wherein the first and second modes are switched. 8. The apparatus according to claim 1, further comprising means for detecting the amplitude of the AC voltage, and means for changing the duty ratio of the PWM signal based on the amplitude of the AC voltage. Inverter device according to. 9. The load is an induction motor, has means for detecting the frequency of the AC voltage, and means for changing the duty ratio of the PWM signal based on the frequency of the AC voltage. The inverter device according to claim 1. 10. The PW when starting the induction motor.
The inverter device according to claim 4 or 9, wherein a DC voltage is applied to the switching element instead of the M signal. 11. An inverter device comprising a power supply line, a load, and a switching element, wherein the switching element is on / off controlled to supply electric power to the load from the power supply line. An inverter device characterized in that a rectified waveform voltage from a rectifying means for rectifying an AC voltage is input to the power supply line. 12. The inverter device according to claim 11, wherein the rectifying means rectifies the AC voltage into a full-wave rectified waveform voltage. 13. The inverter device according to claim 11, wherein the rectifying means rectifies the AC voltage into a half-wave rectified waveform voltage. 14. The inverter device according to claim 11, wherein the rectifying means is provided with a capacitor, and the AC voltage is rectified into a pulsating rectified waveform voltage. 15. The inverter device according to claim 11, wherein two switching elements are connected in series. 16. The inverter device according to claim 11, wherein the four switching elements are connected in a full-bridge type. 17. The inverter device according to claim 11, wherein the switching element is controlled based on the zero-cross point of the AC voltage.