JP2943180B2 - Inductive load drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention] (Industrial application field) The present invention relates to an inductive system in which a plurality of inductive loads excited to have two simultaneous excitation periods are PWM-controlled. The present invention relates to a load driving device.

(Prior Art) FIG. 9 shows an example of a conventional driving device for a four-phase variable reluctance motor, for example. That is, 1 is an AC power supply, 2 is a DC power supply circuit for obtaining a DC power supply from the AC power supply 1, and 3 is a smoothing capacitor of the DC power supply circuit 2. 4 _{1 to} 4 ₄ are first to fourth phase motor coils as four inductive loads,
5 _1, 6 ₁ to 5 _4, 6 ₄ are semiconductor switching elements serving transistor for Tsudan charge controlling a motor coil 4 ₁ to 4 ₄ These first phase to fourth-phase. Figure 10 (a) to (d) shows the excitation period signal SE ₁ to SE ₄ determines the exciting period of the motor coil 4 ₁ to 4 ₄ in the first phase to fourth-phase, 90-degree position to each other It is a 180-degree excitation type having a phase difference. As is apparent from Figure 10, each phase of the motor coil 4 ₁ to 4 ₄ has a period of two-phase excitation. And
Each phase of the motor coil 4 ₁ to 4 _4, PW in each excitation period
M control is performed, so that the speed of the variable reluctance motor is controlled so as to reach the set speed.
That is, when the PWM control of each phase of the motor coil 4 ₁ to 4 _4, the fundamental wave V _S consisting of a triangular wave as shown in FIG. 11 (a)
Conduction period of each phase of the motor coil 4 ₁ to 4 ₄ are determined by comparing the level signal V _L corresponding to the speed signal. In this case, for example, the motor coil 4 of the _first and second phases and 4 ₂
The, in the period of the two-phase excitation, FIG. 11 (b) and the transistors 5 ₁ As shown in (c), 6 ₁ and 5 _2, 6 ₂ to energizing signal (gate signal) G ₁ and G ₂ by given, FIG. 11 (d) and the voltage V ₁ and V ₂ as shown by (e)
Is applied.

In the variable reluctance motor (invention SUMMARY is), the motor coil 4 ₁
Or between 4 ₄ and the frame ground, for example, as shown in FIG. 9, there is very small capacitance C between the motor coil 4 ₁ and 4 ₂ and the frame ground 7, the motor coil 4 ₁ as well as
4 voltages V ₁ and V ₂ are applied to the ₂ transistors 5 _1, 6 ₁ and 5
_{When a} high-speed switching operation is performed so as to be turned on and off at ₂ , 62, a large voltage change rate (dv / dt) occurs,
As a result, as shown in FIGS. 11 (f) and (g), displacement currents, that is, leakage currents i ₁ and i ₂ flow. This leakage current i ₁ and i
₂ is represented by C · dv / dt, and increases as dV / dt increases. Therefore, the leakage current i ₁ and i ₂ as a leakage current due to the motor coil 4 ₁ and 4 ₂ voltages V ₁ and V ₂ are simultaneously applied
Becomes i ₁ + i _{2 as} shown in FIG. 11 (h), which is an extremely large value.

In recent years, the switching speed of semiconductor switching elements has been increasingly increased, and some of them have reached the ultrasonic range. This is effective in that noise can be reduced. The currents i ₁ and i ₂ become large, that is, the leakage current i ₁ + i ₂ becomes extremely large, which poses a safety problem, and sometimes the earth leakage breaker operates.

In order to solve such a problem, it is conceivable that the variable reluctance motor has a double insulation structure, but this causes a new problem that it becomes expensive, and sometimes a 0.1 mm
In the variable reluctance motor which needs to secure the above air gap, it is difficult to form a double insulation structure.

The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce leakage current even when a plurality of inductive loads excited to have a period of two simultaneous excitations are PWM-controlled. An object of the present invention is to provide an inductive load driving device that can be reduced as much as possible.

[Constitution of the Invention] (Means for Solving the Problems) The present invention provides a drive device for an inductive load in which a plurality of inductive loads that are excited so as to have two simultaneous excitation periods are PWM-controlled. , Characterized in that control means is provided for performing a time difference control such that one end time coincides with the other start time of the conduction period by PWM control of the two inductive loads during the period of simultaneous excitation. .

(Operation) According to the inductive load driving device of the present invention, the energization periods of the two inductive loads during the period of simultaneous excitation do not overlap, and therefore, leakage current does not overlap. The leakage current can be made as small as possible.

(Embodiment) Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

 First, the overall configuration will be described with reference to FIG.

AC power supply 10 is connected to an input terminal of DC power supply circuit 11. The DC power supply circuit 11 rectifies the AC power supply voltage, boosts it as necessary, and outputs it as a DC voltage to the power supply lines 12 and 13 connected to the output terminals. The smoothing capacitor 14 is connected.

The motor, for example, the variable reluctance motor 15 includes a plurality of four-phase motor coils 16 _{1 to} 1 serving as inductive loads on the stator.
It includes a 6 _4, by energizing the first through the motor coil 16 ₁ to 16 ₄ of the fourth phase according to the rotation of the rotor, those structure known to cause a torque on the rotor. And
In each of these motor coils 16 _{1 to} 16 ₄ , one terminal thereof is connected to the power supply line 12 through a current detection resistor 17 _{1 to} 17 ₄ and an NPN transistor 18 _{1 to} 18 ₄ as a semiconductor switching element in series. is, the transistors 19 ₁ to 19 for each other terminal semiconductor switching element serving as an NPN
₄ are connected to the power supply line 13 via each. These transistors 18 ₁ , 19 _{1 to} 18 ₄ , 19 ₄ are for switching the excitation current of the corresponding motor coils 16 _{1 to} 16 ₄ , and their bases are connected to the respective output terminals of the drive circuit 20. Energization signals (gate signals) G _{1 to} G ₄
Is given. Diodes 21 ₁ and 22
₁ to 21 _4, 21 ₄ are used to secure the circuit for supplying a current (regenerative current) delay when transistors 18 _1, 19 ₁ to 18 _4, 19 ₄ off.

The variable reluctance motor 15 is provided with first and second optical rotary encoders 23 and 24. The first rotary encoder 23 corresponds to a rotational position detecting means for detecting the rotational position of the rotor, and the A and B two-phase magnetic pole signals having a phase difference of 90 degrees in electrical angle corresponding to the magnetic pole of the rotor.
And outputs the S _P. The second rotary encoder 24 for detecting the rotational speed of the rotor and outputs a pulse train signal S _R corresponding to the rotational speed. The output terminal of the second rotary encoder 24 is connected to the input terminal of the F / V conversion circuit 25, so as the pulse train signal S _R is converted into a voltage signal S _V. Further, the output terminal of the F / V conversion circuit 25 is connected to the negative (-) side input terminal of the subtracter 26 to which the speed command signal V ^* from the external NC machine is applied to the positive (+) side input terminal. Have been. As a result, a speed feedback system is formed, and the subtracter 26 outputs a speed deviation signal ΔV corresponding to the deviation between the command speed and the actual speed. The output terminal of the subtracter 26 is a PID (proportional / integral / differential) compensation circuit 2
7, the speed deviation signal ΔV
Is output as a current command signal I ^* with improved responsiveness and stability. Then, the output terminal of the PID compensator 27 is connected to the positive input terminal of the subtractor 28 ₁ to 28 ₄ for each phase.

On the other hand, the negative side input terminal of each phase of the motor coil 16 ₁ to 16 ₄ to the detection terminal of the current detecting resistor 17 ₁ to 17 ₄ connected in series isolation circuit 29 via a subtracter 28 ₁ to 28 ₄ It is connected to, thereby, the current command signal I ^* subtractor 28 in ₁ to 28 ₄ actual current detection signal SI ₁ to SI ₄ are compared. These subtractors 28 ₁ to 28 ₄ outputs a current deviation signal [Delta] I ₁ [Delta] I ₄ between the actual current and the command current, the output terminal of each is PI (proportional-integral) compensation circuit 30 ₁ to 30 ₄ through it and is connected to the input terminals I a PWM (pulse width modulation) circuit 31 ₁ to 31 _4.

Now, PWM circuits 31 ₁ to 31 ₄ are those constituting the control means 34 together with the first and second fundamental wave generating circuit 32 and 33. The first fundamental wave generating circuit 32 outputs, for example, a first fundamental wave V _S (see FIGS. 3 (a) and 4 (a)) as a sawtooth wave, and its output terminal is a second fundamental wave V _S. PWM circuit 31 for input and a first phase and the third phase of the fundamental wave generating circuit 33 ₁ and 31
₃ is connected to each input terminal Ib. The second fundamental wave generating circuit 33 and the second fundamental wave by inverting the first fundamental wave V _S
It outputs V _R (see FIGS. 3 (b) and 4 (b)), and its output terminal is a PWM circuit 3 for the second and fourth phases.
It is connected to one ₂ and 31 ₄ each of the input terminals 1 b of. In this case, PWM circuits 31 ₁ to 31 _4, as well known, according to the current deviation signal [Delta] I ₁ to [Delta] I _4, it outputs a PWM signal P ₁ to P ₄ pulse width becomes wider as there if large The output terminal is connected to each input terminal of the drive circuit 20 via the excitation period control circuit 35. This excitation period control circuit 35
The output terminal of the excitation period determination circuit 36 is connected to the input terminal of the first stage, and the output terminal of the first rotary encoder 23 is connected to the input terminal of the excitation period determination circuit 36. Here, the excitation period determining circuit 36 outputs a first second view from the pole signal S _P output from the rotary encoder 23 (a) to the excitation period signal SE ₁ to SE ₄ as shown in (d), these excitation period signal SE ₁ to SE ₄ is of a and 180-degree excitation method has a phase difference of 90 degrees from each other. When the excitation period signal SE ₁ to SE ₄ from the excitation period determining circuit 36 is supplied to the exciting period control circuit 35, the exciting period control circuit
The reference numeral 35 designates a period in which each of the excitation period signals SE _{1 to} SE ₄ is present (high-level period), and passes the corresponding PWM signal P _{1 to} P ₄ to the drive circuit 20 to supply the drive signal to the drive circuit 20. and outputs a signal (gate signal) G ₁ to G _4. Phase 1 to 4
The motor coil 16 ₁ to 16 ₄ of the phases, to flow pulse-modulated excitation current by transistors 18 _1, 19 ₁ to 18 _4, 19 ₄ is turned on by energizing signal G ₁ to G _4.

Next, the operation of this embodiment will be described with reference to FIGS.

Assuming now that the variable reluctance motor 15 is rotating, the excitation period determining circuit 36
The second view corresponding to the magnetic pole signal S _P output A, B2 phase output from the 23 (a) and together with the first phase and outputs the excitation period signal SE ₁ and SE ₂ of the second phase as shown in (b) these exciting period signal SE ₁ and SE ₂ Figure 2 obtained by inverting the (c) and (d)
The third and fourth phase excitation period signals SE ₃ and SE _{4 as shown in FIG.}
Is output. Further, PWM circuits 31 ₁ and for the first and third phases
31 _3, Figure 3 from the first basic waveform generating circuit 32 (a)
And a first fundamental wave V _S as shown in FIG.
PWM signal P of the pulse width based on magnitude of the level signal by comparing the level signal corresponding to ₁ and 28 ₃ to PI compensating circuit 30 ₁ and 30 ₃ current deviation supplied via a signal [Delta] I ₁ and [Delta] I _{3 1} and P ₃ are output, and PWM circuits 31 ₂ for the second and fourth phases are output.
And 31 _4, FIG. 3 (b) and FIG. 4 (b) to as shown second fundamental wave V _R and PI compensating circuit from the subtractor 28 ₂ and 28 ₄ from the second fundamental wave generating circuit 33 compares the level signal corresponding to 30 ₂ and the current deviation signal applied through 30 ₄ [Delta] I ₂ and [Delta] I ₄ of the pulse width based on magnitude of the level signal
And outputs a PWM signal P ₂ and P _4. Furthermore, the excitation period control circuit 3
5 is PW while the first phase excitation period signal SE ₁ is given.
Outputs M signals P _1, while the exciting period signal SE ₂ of the second phase is given by outputting the PWM signal P _2, the excitation period signal S of the third phase
While the E ₃ is given by outputting the PWM signal P _3, while the excitation period signal SE ₄ of the fourth phase is given to output a PWM signal P _4. The output from the excitation period control circuit 35
PWM signal P ₁ to P ₄ is applied to the base of the output transistor 18 _1, 19 ₁ to 18 _4, 19 ₄ as energizing signals G ₁ to G ₄ from the drive circuit 20, than Te, the first phase to fourth Phase motor coil
The PWM control of 16 _{1 to} 16 ₄ is performed.

Now, we describe Figure 3 and first and second phase of the motor period of two-phase excitation coils 16 ₁ and 16 ₂ in accordance with Figure 4. PWM circuit 31 ₁ for the first phase, as shown in FIG. 3 (a) and 4 (a), the first fundamental wave V _S and the current deviation signal Δ
Compares the level signal VL ₁ corresponding to I _1, FIG. 3 (c)
And output a PWM signal P ₁ as shown in FIG.
This is output as a current signal G ₁ through the exciting period control circuit 35 and the driving circuit 20. Further, PWM circuit 31 ₂ for the second phase,
As shown in FIG. 3 (b) and FIG. 4 (b), by comparing the level signal VL ₂ corresponding to the second fundamental wave V _R and a current deviation signal [Delta] I _2, FIG. 3 (d) and as shown in FIG. 4 (d), and outputs a PWM signal P _2, which is output as a current signal G ₂ through the exciting period control circuit 35 and the driving circuit 20. Accordingly, the transistors 18 ₁ , 19 ₁ and 18 ₂ , 19 ₂ are turned on, respectively, and the first and second phase motor coils 16 ₁ and 16 ₂ are provided in FIGS. 3 (e) and (f) and FIG. Although the voltage V ₁ and V ₂ are applied as shown in (e) and (f), as described above,
Energizing signals G ₁ and G ₂ from being formed from two of the fundamental wave V _R obtained by the first fundamental wave V _S and inverting it, it will have a time difference so that the mismatch condition. Here, FIG. 3 shows that the duty ratio of the PWM signals P ₁ and P ₂ is 1: 1.
FIG. 4 shows a case where the duty ratio is other than 1: 1.

In the case of FIG. 3, the first and second phase motor coils
Since the applied voltages V ₁ and V ₂ of 16 ₁ and 16 ₂ rise from the low level to the high level and fall from the high level to the low level, that is, the energization start time and the energization end time completely match, the first phase leakage current i ₁ by the motor coil 16 ₁
, As shown in FIG. 3 (g), and the leakage current i ₂ of the second phase of the motor coil 16 ₂ is as shown in FIG. 3 (h). Therefore, the two leakage currents i ₁ and i ₂ are substantially canceled out by being combined, and become substantially zero as shown in FIG. 3 (i).

In the case of FIG. 4, the first phase of the falling and the motor coil 16 ₂ of the applied voltage V of the second phase of the applied voltage V ₁ of the motor coil 16 ₁
Since the _second rise is matched, leakage current i ₁ by the motor coil 16 ₁ of the first phase is as shown in FIG. 4 (g), and the leakage current i of the motor coil 16 ₂ of the second phase _Two
Is as shown in FIG. 4 (h). Accordingly, as shown in FIG. 4 (i), in the fall and unmatched portion of the rise of the applied voltage V ₁ and V _2, although the leakage current i ₁ or i ₂ is produced as it is, it applied voltages V ₁ and in the fall and matching parts of the rise of the V _2, the leakage current i ₁
And i ₂ are canceled out to be substantially zero.

Above, although those described for the motor coil 16 _1, 16 ₂ as a 2-phase excitation, it is also similar to the above for the other phases. That is, the energization signal G ₄ for the fourth phase of the motor coil 16 ₄ comprising the motor coil 16 ₁ of the first phase and 2-phase excitation,
Because it is formed on the basis of the second fundamental wave V _R, energizing signals G ₁
It comes to have a time difference so that the mismatch condition is a current signal G ₄ and. Further, the energization signal based on the first fundamental wave V _S
G ₃ energization signals G ₂ and G ₄ are for the second phase and the fourth phase of the motor coil 16 ₂ and 16 ₄ to the motor coil 16 ₃ of the third phase obtained with two-phase excitation, the second fundamental wave V because they are formed on the basis of the _R, it comes to have a time difference so that the mismatch condition is a current signal G ₃ and energization signals G ₂ and G _4.

Thus, in this embodiment, formed on the basis of the energization signals G ₁ and G ₃ for the motor coil 16 ₁ and 16 ₃ of the first phase and the third phase to the first fundamental wave V _S, these and 2 so as to form the basis of the energization signals G ₂ and G ₄ for the second phase and the fourth phase motor coil 16 ₂ and 16 ₄ to the phase excitation to the second fundamental wave V _R obtained by inverting the fundamental wave V _S did. Therefore, the energization periods of the motor coils of each phase that are two-phase excitation do not overlap, and as a result, the leakage current can be made as small as possible, and unlike the conventional case, the safety is sufficiently improved. Can be secured and the earth leakage breaker does not operate,
In addition, the variable reluctance motor 15 does not need to have a double insulation structure, and can be manufactured at low cost.

FIGS. 5 to 7 show a second embodiment of the present invention. Only the parts different from the first embodiment will be described below. While the signal forming signal is configured as hardware, the signal forming signal is configured as software using a microcomputer 37 as control means.

That is, the arithmetic unit 38 with the speed command signal V ^* and the actual current detection signal SI ₁ to SI ₄ is given through the A / D converter circuit 39 and 40, the pulse train signal S _R is given, furthermore, the system System clock signal from clock generation circuit 41
S _CK is provided. Signals are transmitted and received between the arithmetic section 38 and the timing counter 42. The timing counter 42 receives a system clock from the system clock generation circuit 41.
S _CK is provided. Here, the timing counter 42 is formed of, for example, a ring counter. When a start signal is given, the timing counter 42 counts the system clock signal _SCK shown in FIG. n "is the fundamental wave V value corresponding to one period of _S) and comprising each a high level (H) and low level (L)
And outputs a timing pulse T _P as shown in FIG. 6 are repeated to replace the (b). The operation unit 38 operates as described later to supply a signal to the PWM signal generation unit 43, and the PWM signal generation unit 43 receives the system clock signal _SCK from the system clock generation circuit 41.
Is also given. In this case, PWM signal generating unit 43 has a first phase to fourth-phase counter 44 ₁ to 44 _4, these are for example made of down counter starts counting down when data is preset During the down-counting, a high-level signal is output.

The operation of the second embodiment will be described with reference to the time chart of FIG. 6 and the flowchart of FIG. Now, when the microcomputer off 37 starts the operation (start), the arithmetic unit 38 first performs a normal initialization operation after the processing step S ₁ of the "initialization" of the "timing counter start" output step S ₂ Becomes Calculation unit 38, in this output step S ₂ will provide a start signal to the timing counter 42, therefore, the timing counter 42 counts the system clock signal S _CK as shown in FIG. 6 (a) 6 outputs a timing pulse T _P as shown in FIG. (b). Next, the arithmetic unit 38
Next input step S ₃ of the "pulse train read", here,
Nde read pulse train signal S _R is stored in the RAM, the processing steps S ₄ of "actual speed calculation". Calculation unit 38, is stored in the RAM and calculates the actual speed from the period of the processing steps S ₄ In example pulse train signal S _R, further, "the speed command reading" migrated speed command signal V in input step S ₅ of Read ^* and RA
Is stored in the M, then proceeds to "rate deviation calculation" for the process step S _6. Calculating section 38, the process in step S ₆ is stored in the RAM and calculates the current deviation signal I ^* from the command speed and the actual speed, the process proceeds to input step S ₇ of the next "actual current reading" real Read the current detection signals SI _{1 to} SI ₄
After storing in the RAM, and the process proceeds to step S ₈ of the "current deviation calculation (pulse width data)". Calculating section 38, the process based on this by calculating the current deviation signal [Delta] I ₁ to [Delta] I ₄ in step S ₈ each phase of the pulse width data "m" (where, n ≧ m ≧ 0) to the determined RAM and Remember. afterwards,
Calculation unit 38, the determination step S ₉ next to "or L → H?",
Decision step of "Is H → L?" When timing pulse T _P of the timing counter 42, it is judged whether the up standing from the low (L) to the high level (H), is determined, for example, "NO" here moves to S _10. Then, the operation unit 38
Determines whether the determination step S ₁₀ in the first phase counter 44 _first output signal (PWM signal P ₁₎ fell standing from the high level (H) to the low level (L), for example, "NO" so that the flow returns to the determination step S ₉ when the decision was. Here, when the timing pulse T _P of the timing counter 42 is up standing from the low (L) to the high level (H) is,
The arithmetic unit 38, in the judgment step S ₉ of "or L → H?""YE
Next output step S ₁₁ of determining that S "," first-phase and third-phase counter to the pulse width data preset ", the first
A phase and preset pulse width data of the first and third phases, "m" in the third phase counter 44 ₁ and 44 _3. Thus, as shown in FIG. 6 (c), the first phase counter 44 ₁
Indicates that the numerical data "m" is preset and counts down, and during this down count, the high level (H) is set.
And outputs the PWM signal P _1. The third phase counter 44 ₃ is also similar, PWM of the down-count during the high level (H)
And outputs a signal P _3. Thereafter, when the first phase and third-phase counter 44 ₁ and 44 ₃ finishes counting down, the PWM
The output of the signal P ₁ and P ₃ is stopped. The arithmetic unit 38 is as if through the processing steps S ₁₁ returns to input step S ₃ of the "pulse train loading". Further, when the output signal serving as PWM signal P ₁ of the counter 44 ₁ first phase fell standing from the high level (H) to the low level "L", the operating section 38, "H → L or?" Decision step S of it is determined "YES" in ₁₀ output step S ₁₂ next to the "second phase and the fourth phase counter to the pulse width data preset", where the first to the second phase and the fourth phase counter 44 ₂ and 44 ₄ The pulse width data “m” of the two phases and the fourth phase is preset. Thus, as shown in FIG. 6 (d), the second phase counter 44 _Numerical data "m"
There During this down-counting while counting down the preset outputs a PWM signal P ₂ at a high level (H). The fourth phase counter 44 ₄ is also similar in its down count outputs a PWM signal P ₄ in the high level (H). Thereafter, the second phase and the fourth phase counter 44 ₂ and 44 ₄ has finished counting down, the output of the PWM signal P ₂ and P ₄ is stopped. The arithmetic unit 38 is as if through the processing steps S ₁₂ returns to the input step S ₁₃ of the "pulse train loading".

PWM signal P ₁ to P ₄ in the second embodiment are those given to the exciting period control circuit 35 in FIG. 1,
Therefore, the same effects as those of the first embodiment can be obtained by the second embodiment.

In the above second embodiment, a decision step S ₁₀ in "or H → L?", PWM signal P ₁ of the first phase counter 44 ₁ is Tsu Tatsuka from the high level (H) to the low level (L) and determining whether Taka not, is divided into the steps of the third phase counter 44 ₃ of the PWM signal P ₃ it is determined whether the down standing from the high level (H) to the low level (L), the step of each in may be configured to preset the respective pulse width data to the second phase counter 44 ₂ and the fourth-phase counter 44 ₄ when it is determined "YES".

Figure 8 is a third embodiment of the present invention, the first and the differs from the second embodiment, the motor coil 16 ₁ to 16 ₄ two motors 45 and instead of 46 as an inductive load Is used. That is, the motors 45 and 46
The parallel operation is controlled by simultaneous excitation by a control device 48 as control means. Again, since there is very small capacitance C between the motor 45 and 46 and the frame 47, there is a problem that leakage currents i ₁ and i ₂ flows. Therefore, the motor 45 and the
When performing the PWM control of 46, similarly to the first or second embodiment, the time difference control is performed so that the passage period of the motors 45 and 46 coincides with the start time of the energization of one of them. It is good. Where frame 47
With connecting the frame 49 of the control device 48 at the ground line 50 and, if the ground via a current meter 51 and the frame 49 of, it is possible to perform the measurement of the leakage current i ₁ and i ₂ by the ammeter 51 .

In the case where the PWM signal is obtained by software using a microcomputer as in the second embodiment,
For example, even if three or more motor coils are excited simultaneously, such as a stepping motor, it is possible to perform PWM control so that these energization periods do not overlap. When two combinations are considered, the energization period is time-controlled so that the end time of one energization coincides with the start time of the other energization.

[Effect of the Invention] As described above, the inductive load driving device according to the present invention has a structure in which even if PWM control is performed with a period during which two or more inductive loads are simultaneously excited, the The current can be reduced as much as possible, so that the safety can be sufficiently ensured, and the earth leakage breaker does not operate, and there is no need to use a double insulation structure. It has the effect that it has.

[Brief description of the drawings]

1 to 4 show a first embodiment of the present invention.
FIG. 2 is an overall electrical configuration diagram, FIG. 2 is an excitation period signal waveform diagram for explaining the operation, FIGS. 3 and 4 are signal waveform diagrams of respective portions for explaining the operation, and FIGS. FIG. 7 shows a second embodiment of the present invention. FIG.
FIG. 7 is a time chart for explaining the operation, FIG. 7 is a flowchart for explaining the operation, and FIG. 8 is a third embodiment of the present invention.
FIG. 9 is a schematic configuration diagram showing an embodiment of FIG.
10 and 11 show a conventional example in FIGS. 1, 2 and 3, respectively.
FIG. In the drawings, the DC power supply circuit 11, the variable reluctance motor 15, 16 ₁ to 16 ₄ motor coil of the first phase to fourth-phase (inductive load), 18 ₁ to 18 ₄ and 19 ₁ to 19 ₄ are transistors , 20 driving circuit, 31 ₁ to 31 ₄ are PWM circuit, the first fundamental wave generating circuit 32, the second fundamental wave generating circuit 33, the control means 34, 35 exciting period control circuit 36 is energized Period determination circuit,
37 is a microcomputer (control means), 38 is an arithmetic unit,
43 is a PWM signal generator, 45 and 46 are motors (inductive loads), and 48 is a control device (control means).

Claims (1)

(57) [Claims] 1. An inductive load driving device in which a plurality of inductive loads excited so as to have a period of two simultaneous excitations is PWM-controlled, wherein two inductive loads during a period of simultaneous excitation are provided. A drive device for an inductive load, characterized in that control means is provided for controlling a time difference so that one end time coincides with the other start time of the energization period by the PWM control of the load.