JP3530449B2 - Inverter driven motor device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter drive motor device provided with a function of protecting an inverter from overcurrent.

[0002]

2. Description of the Related Art Such an inverter drive motor device 20
0 is used, for example, as a compression unit for compressing a refrigerant in a refrigerating device or an air conditioner, as a drive source for an electric fan, etc., and as an electric motor (hereinafter referred to as a motor), various motors such as a DC brushless motor are used. For example, the configuration of an inverter drive motor device 200 in which the motor 3 is driven by the inverter 2 as shown in FIG. 5 is well known. Note that, in each of the following drawings, the portions denoted by the same reference numerals have the same functions as the portions having the same reference numerals described in any of the drawings.

Referring to FIG. 5, the microcomputer 5 drives the inverter 2 by applying a control signal for continuously rotating the motor 3 to the drive circuit 4 to control the drive circuit 4. Is each power transistor (hereinafter referred to as transistor) TU / TV / T
The W, TX, TY, and TZ are used to drive the motor 3 by converting the DC power supply 1 into a plurality of phases, for example, a three-phase AC power supply.

The transistors TU to TZ are driven by
Position detection part (not shown) for detecting the position of the rotor 3R
Is supplied to the microcomputer 5 to control the rotor 3R to rotate synchronously. The DC power supply 1 is, for example, an AC power supply (not shown), for example, a DC power supply obtained by rectifying and smoothing an AC voltage obtained by transforming a commercial AC power supply into a required voltage.

The overcurrent detection circuit 6 is detected by a current detection element for detecting a current supplying a current from the DC power supply 1 to the inverter 2, for example, a current detection resistor Rs arranged in a negative-side electric circuit of the inverter 2. This is a part for detecting whether or not the direct current value exceeds a predetermined amount, that is, whether or not it is an overcurrent.

When an overcurrent is detected, the overcurrent detection circuit 6 gives an overcurrent detection signal 6A indicating that it is an overcurrent to the microcomputer 5 via the overcurrent abnormality holding circuit 7, and the microcomputer 5
Controls the drive circuit 4 to stop the driving of the inverter 2, and an overcurrent protection operation is performed. With this overcurrent protection operation, after the driving of the inverter 2 is stopped, a control signal from the microcomputer 5 is sent. The abnormality canceling circuit 8 cancels the abnormality holding of the overcurrent abnormality holding circuit 7.

The overcurrent abnormality holding circuit 7 is, for example,
The abnormality canceling circuit 8 is configured so that the abnormality holding by the flip-flop circuit is canceled by a transistor Tr provided with a protection resistor Rr on the input side, for example. There is.

The overcurrent detection circuit 6 includes a comparator Cp,
Circuit DC power supply Vcc, overcurrent detection resistors R1 and R2,
The reference voltage resistors R3 and R4 are included. Since the DC power supply 1 has a voltage of 280 V and the circuit DC power supply Vcc has a voltage of 5 to 15 V, the DC power supply 1 and the circuit power supply Vcc are separate power supplies. When the voltage is low and can be configured with a voltage similar to that of the circuit DC power supply Vcc, the DC power supply 1 and the circuit DC power supply Vcc may be configured to be the same. In this case, it is necessary that the voltage of the portion corresponding to the circuit DC power supply Vcc is not changed when an overcurrent occurs.

The respective parts of the overcurrent detection circuit 6 are set under the following operating conditions. In the following mathematical expression, Vcc represents the voltage of the circuit DC power supply Vcc, and the voltage Em1 at the positive terminal of the comparator Cp, that is, the + terminal, is as shown in the following mathematical expression (1).

Em1 = Vcc · R4 / (R3 + R4) (1) Further, the current Is flowing in the current detection resistor Rs is directed from the negative electrode circuit side of the inverter 2 to the negative electrode of the DC power source 1 as indicated by an arrow. The flow direction is positive and each resistance is R1.
>> Rs, R2 >> Rs, comparator C
The voltage Em2 at the negative terminal of p, that is, at the negative terminal is as shown in the following mathematical expression (2). Em2 = (-Is.Rs) + [(Vcc + Is.Rs) R2 / (R1 + R2)] = (R2.Vcc-R1.Rs.Is) / (R1 + R2) (2) Therefore, when Em1 <Em2 , Comparator C
p output, that is, the overcurrent detection signal 6A is low level L
When it is ow and Em1> Em2, the output of the comparator Cp, that is, the overcurrent detection signal 6A is configured to be a high level High.
The overcurrent detection signal 6 having a waveform like [comparator output voltage] is output.

The operation waveforms of the respective parts in FIG. 6 are operation examples when the inverter 2 and the motor 3 are constituted by a three-phase DC brushless motor, and the transistors TU to TZ of the inverter 2 are fixed to the motor 3 respectively. Sub winding 3U / 3V / 3
It is configured to perform three-phase driving in which W is energized for a phase of 120 °. In [energized phase] [transistor drive waveform] of FIG. 6, the U-phase transistor TU is energized, O of the Y-phase transistor TY due to chopping
This is an operation example in the state where N / OFF is performed to energize in a fine pulse state.

In addition, each transistor TU in this operation state
7 to 9 are indicated by the thick arrow lines, and when both the U-phase transistor TU and the Y-phase transistor TY are ON, as shown in FIG.
The above positive current flows through the overcurrent detection resistor Rs, and U
When the phase TU is in the ON state and the Y phase TU is in the OFF state, the freewheeling diode DV connected in parallel to the V phase transistor TV as shown in FIG.
Because the current flows through the resistor, the overcurrent detection resistor Rs
No current flows through.

Here, even after the energization of all the transistors TU to TZ is stopped, the stator windings 3U.3 of the motor 3 are
The energy stored in V flows in the opposite direction, and this becomes regenerative current Ir, and as shown in FIG.
And a current flowing through the freewheeling diode DX connected in parallel to the X-phase transistor TX, a current flows in the negative direction that flows in the overcurrent detection resistor Rs in the opposite direction to the positive direction. .

In the case of the energized state according to the [transistor drive waveform] of FIG. 6, in the normal state, Em1 <Em2 and the overcurrent detection signal 6A = Low. Therefore, the abnormality holding circuit 7 is the [abnormality holding circuit] of FIG.
The signal on the “normal” side in the above, that is, the signal on the low level side is given to the microcomputer 5, and since the microcomputer 5 gives the control signal for driving all the transistors TU to TZ to the drive circuit 4, Transistors TU to T
Z operates to supply a three-phase alternating current to the motor 3.

When the position detection signal of the rotor 3R is not obtained for some reason, the current value given from the DC power supply 1 to the inverter 2 is, for example, an overcurrent damage to the transistors TU to TZ due to an overcurrent, The value becomes a predetermined value for preventing demagnetization of the magnetic poles of the rotor 3R.
s current and overcurrent protection level], for example, when a current reaching the “overcurrent protection operation level Is1” flows in the overcurrent detection resistor Rs, The voltage drops to a predetermined value and the comparator Cp
6 is in the state of [comparator positive / negative terminal input voltage (overwrite)] [comparator output voltage] in FIG. 6, and Em1> Em2 abnormality detection signal 6A = High. A signal of "abnormal" level is given to the microcomputer 5 like the "abnormality protection circuit" of 6, and the microcomputer 5 detects all the transistors T
A control signal for stopping the driving of U to TZ is given to the drive circuit 4, all the transistors TU to TZ operate, and the transistors TU to TZ themselves do not give a current to the motor 3.

The current flowing through the motor 3 is the current value I as shown in [Rs current and overcurrent protection level] in FIG.
Since it shifts to the sn side, the current flowing through the overcurrent detection resistor Rs falls below the “overcurrent protection operation level Is1”, and the overcurrent detection signal 6A of the comparator Cp shifts to the Low side as shown in [Comparator output voltage] in FIG. Returning to this, the overcurrent abnormality holding circuit 7 continues to hold the "abnormal" state as shown by the "abnormality holding circuit" in FIG. 6, and this holding is carried out by the abnormality clearing circuit 8 under the control of the microcomputer 5. When it is done, it is released and returns to the "normal" side.

Here, in [Rs current and overcurrent protection level] in FIG. 6, the portion where the "regeneration current period" after the inverter 3 is stopped flows to the "-A" side is as described above. Inverter 3 stator winding transistors TU to T
Z itself does not apply a current to the motor 3, but is a portion of the regenerative current Ir generated by the energy stored in the stator windings 3U and 3V of the motor 3. That is, in this rotating state, the motor 3 is performing the same power generation operation as the generator, and the current generated by this power generation operation appears as the regenerative current Ir.

[0018]

SUMMARY OF THE INVENTION In the above prior art,
In addition to the overcurrent detection circuit, an overcurrent abnormality holding circuit and an overcurrent abnormality cancellation circuit for canceling this holding must be provided, so a device with a complicated configuration cannot be provided simply and inexpensively. Since an abnormality or a failure occurs in the overcurrent abnormality holding circuit / overcurrent abnormality cancellation circuit, there is a disadvantage that maintenance work becomes complicated. Therefore, there is a problem that it is desired to provide a device that eliminates such inconvenience.

[0019]

According to the present invention, an electric motor is driven by an inverter for converting a direct current power source into an alternating current power source as described above, and the current supplied from the direct current power source to the inverter is detected. An inverter drive motor device for holding and canceling the overcurrent protection operation for stopping the drive of the above-mentioned inverter based on the output obtained by comparing the detected voltage obtained by the comparison with a predetermined reference voltage by a comparator. At

For the hysteresis operation of the above comparator
Based on the first configuration, a holding release means for holding and releasing the above is provided.

In the first configuration, when the regenerative current of the motor after the stop has reached a predetermined negative current, the above-mentioned cancellation is performed based on the reset operation of the hysteresis operation. The second configuration according to

In the above-mentioned first structure, the microcomputer for controlling the drive of the above-mentioned inverter does not perform the reset operation of the above hysteresis operation by the regenerative current of the above-mentioned electric motor after the above-mentioned stop. The above problem is solved by the third configuration in which the above-mentioned cancellation is performed based on the control.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION As an embodiment of the present invention, an inverter drive motor device 200 having the configuration shown in FIG.
First, an embodiment to which the present invention is applied will be described with reference to FIGS. In FIGS. 1 to 4, portions indicated by the same reference numerals as those in FIGS. 5 to 7 have the same functions as the portions indicated by the same reference numerals in FIGS. Further, in FIGS. 1 to 4, the portions denoted by the same reference numerals have the same functions as the portions having the same reference numerals described in any of FIGS. 1 to 4.

[0024]

[Embodiment] [First Embodiment] The first embodiment will now be described with reference to FIGS. 1 and 2.
An example will be described. In general, the configuration of the first embodiment constitutes the first configuration and the second configuration described above. The points different from the configuration of the prior art in FIG. 5 are as follows. Is.

First, the abnormal current detection circuit 6 and the microcomputer 5 are eliminated by removing the overcurrent abnormality holding circuit 7 and the abnormality cancellation circuit 8.
By this, the operation is performed in place of the overcurrent abnormality holding circuit 7 and the abnormality cancellation circuit 8.

Second, the capacitor C2 is connected between the positive terminal of the comparator Cp, that is, the + terminal and the ground, and the feedback circuit by the resistor R5 is provided between the + terminal and the output terminal. 2 is a portion where the comparator Cp is made to perform the hysteresis operation as shown in FIG. 2 by connecting the capacitor C1 between the negative terminal of the above, that is, the negative terminal and the ground. The comparator Cp is of an open collector output circuit type.

That is, specifically, the above equation (1)
When the condition according to (2) is set to be the same and the input voltage Em1 of the + terminal when the output of the comparator Cp is at the low level Low is Em1a, Em1a = Vcc (R4 // R5) / [R3 + (R4 // R
5)] becomes.

Further, when the output of the comparator Cp is at high level High, the input voltage Em1 at the + terminal is Em1.
If b, then Em1b = VccR4 / (R3 + R4).

The capacitors C1 and C2 are set so that the output of the comparator Cp becomes a low level Low during the initial operation when the circuit DC power supply Vcc is applied to the comparator Cp, and the capacitance of the capacitors C1 and C2 is set. The value is set to a minute capacity that does not affect the operation of each part during overcurrent protection operation.

Further, the resistors R1 to R5 have the current Is detected by the current detection resistor Rs as in the state before the overcurrent protection operation in [Rs current and overcurrent protection level] of FIG. , an overcurrent protection level Is1, when is <Is1 overcurrent detection signal 6A = Low, so that Em1 <Em2, is set to the condition of the following formula (3).

{(R4 // R5) / [R3 + (R4 // R5)]} <[R2 / (R1 + R2)] ... (3) Then, Is1 <Is, and [Comparator of FIG. Output voltage], after the overcurrent detection signal 6A = High and once the overcurrent protection operation is performed, even if Is = 0, the state of Em1> Em2 is maintained, Like [Comparator positive terminal input voltage] in 2, the circuit constants are set so that the overcurrent detection signal 6A = High is maintained and the overcurrent protection operation is held. (4)
It becomes the state of.

[(R4 / (R3 + R4)]> [R2 / (R1 + R2)] (4) In the state where this overcurrent protection operation is held, [Rs current and overcurrent protection level in FIG. ], Regenerative current
The current value of the negative current portion of Ir decreases, and even if the current Ir becomes zero, the current state continues, and [Rs of FIG.
Current and overcurrent protection level]
At s2, that is, Em1 <Em2, and the circuit constants are set so as to invert to the overcurrent detection signal 6A = Low as shown in [Comparator positive terminal input voltage] in FIG. Therefore, the comparison state in the comparator Cp is as shown in FIG. 2 [comparator positive / negative terminal input voltage (overwrite)].

As described above, the level of the compared input applied to the-terminal of the comparator Cp once exceeds the level of the first comparison input, and the comparison output obtained by inverting the comparison output is output.
Operation carried out, i.e., after the inversion operation, the level of the comparison input even down to the level of the comparison input, maintains its comparison output, further, is down to a second level
In this invention, the hysteresis operation of the comparator means that the return operation for returning the comparison output to the original comparison output state, that is, the reset operation is performed.

Then, in the first embodiment, the predetermined current value for performing the reset operation in the hysteresis operation of the comparator Cp is set to the overcurrent protection of [Rs current and overcurrent protection level] in FIG. Release level Is2
As described above, the regenerative current Ir of the motor 3 generated after the driving of the inverter 2 is stopped by the microcomputer 5 and the driver circuit 4 is set to a current value which becomes a predetermined current value Is2.

In this first embodiment, the three-phase DC brushless motor as described above is applied, but the motor 3 such as a general induction motor is approximated by a sine wave type pulse width modulation. It is a range that can be implemented by a person skilled in the art, as a matter of course, according to the person skilled in the art, that the overcurrent protection operation can be similarly applied by applying the configuration in the case of being driven by the inverter 2 that outputs a voltage. The description is omitted here.

[Second Embodiment] A second embodiment will be described below with reference to FIGS. The configuration of the second embodiment generally comprises the first configuration and the third configuration described above, and the points different from the first configuration described above are as follows.
This is a place where the abnormality canceling circuit 8 is added and the canceling operation is performed by the control of the microcomputer 5.

In FIG. 3, at the start of the operation of the apparatus, the microcomputer 5 detects the abnormality cancellation circuit 8 when the circuit DC power supply Vcc reaches a predetermined voltage value before driving the inverter.
Is reset to the abnormal state, the output of the comparator Cp of the overcurrent detection circuit 6, that is, the overcurrent detection signal 6A is reset to the low level Low side. After performing such an operation, the microcomputer 5 supplies a control signal for driving the inverter 2 to the drive circuit 4 to drive the inverter 2 so that the motor 3 is continuously rotated.

Then, the overcurrent detection circuit 6 includes the first
Similar to the embodiment, the comparator C detects an overcurrent condition and
When the microcomputer 5 is provided with an output in which the p overcurrent detection signal 6A is set to the high level High, the microcomputer 5 causes the drive circuit 4 to operate.
The overcurrent protection operation is held so as to stop the driving of the inverter 2 by controlling.

However, the reset operation level Is2A capable of performing the reset operation in the hysteresis operation of the comparator Cp is set to [Rs current and overcurrent protection level] in FIG.
Like the reset operation level of, the negative current value is larger than the maximum value Isn of the negative current due to the regenerative current Ir, and | Is2A |> | Isn | is set, so the reset operation in the hysteresis operation is performed. Since it cannot be performed, the state in which the overcurrent protection operation is held is maintained.

That is, unlike the [abnormality holding circuit] of FIG. 4, the abnormality detection signal 6A cannot be returned to the low level Low state by the operation of the comparator Cp. Therefore, the comparison state in the comparator Cp is as shown in FIG. 4 [comparator positive / negative terminal input voltage (overwrite)].

Whether a short pulse-like control signal 8A is given from the microcomputer to the abnormality clearing circuit 8 when a clock circuit (not shown) provided in the microcomputer 1 measures a predetermined time, for example, 10 seconds. Or, by giving a control signal 8A from the microcomputer 5 to the abnormality canceling circuit 8 based on a signal from an operating section (not shown) of the microcomputer 5 and grounding the + terminal of the comparator Cp by the abnormality canceling circuit 8, The reset operation of the hysteresis operation of the comparator Cp is performed.

Therefore, in the configuration of the second embodiment, the regenerative current I of the motor 3 after the driving of the inverter 2 is stopped
Depending on r, the resetting operation of the hysteresis operation of the comparator Cp is not performed, but the abnormality is held under the control of the microcomputer 5 that controls the drive of the inverter 2, that is,
The holding of the overcurrent protection operation is released.

[0043]

Effects of the Invention According to the present invention, as described above, the hysteresis operation of the comparator itself provided in the abnormality detection circuit, and is subjected to release the holding of the overcurrent protection operation DOO
In addition, release the negative current or regenerative current of the motor.
Based on the control of the microcomputer that controls the drive of the burner.
Since it is not necessary to provide an overcurrent abnormality holding circuit or an overcurrent abnormality holding circuit and an abnormality clearing circuit as in the past, maintenance work due to a failure of these circuits becomes unnecessary, and the device There is an effect that can be provided simply and cheaply.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention, and FIG.
9 shows the prior art, and the contents of each figure are as follows.

FIG. 1 is an overall block configuration diagram.

[Fig. 2] Operation waveform diagram of main parts

[FIG. 3] Overall block configuration diagram

FIG. 4 is an operation waveform diagram of main parts.

[FIG. 5] Overall block configuration diagram

FIG. 6 is an operation waveform diagram of main parts.

FIG. 7 is an operation state diagram of main parts.

FIG. 8 is an operation state diagram of main parts.

FIG. 9 is an operation state diagram of main parts

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 DC power supply 2 Inverter 3 Motor 3R Rotor 3U / 3V / 3W Stator winding 4 Drive circuit 5 Microcomputer 6 Overcurrent detection circuit 6A Overcurrent detection signal 7 Overcurrent abnormality holding circuit 8 Abnormality cancellation circuit 200 Inverter drive electric motor device C1 C2 capacitor Cp comparator DU to DZ diode Em1 + terminal voltage Em2 − terminal voltage Ir regenerative current Is current Is1 overcurrent protection operation level Isn maximum regenerative current Rr protection resistor Rs current detection resistor R1 and R2 overcurrent detection resistor R3 R4 resistance for reference voltage R5 resistance TU to TZ transistor U U phase V V phase Vcc DC power supply W W phase for circuit

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yuichi Izawa 2-5-5 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd. (56) Reference JP 2000-32773 (JP, A) JP JP 10-197572 (JP, A) JP 5-344742 (JP, A) JP 62-235630 (JP, A) JP 2000-32771 (JP, A) (58) Fields investigated (Int.Cl) . ⁷ , DB name) H02M 7/48 F25B 13/00 H02P 6/12 H02P 7/00

Claims (3)

(57) [Claims] 1. A comparator for driving a motor by an inverter that converts a DC power supply into an AC power supply, and detecting voltage obtained by detecting a current supplied to the inverter from the DC power supply and a predetermined reference voltage. An inverter drive motor device that holds and releases an overcurrent protection operation that stops driving of the inverter based on an output that detects an overcurrent by comparison with the above, based on a hysteresis operation of the comparator ,
An inverter-driven electric motor device comprising a holding release means for holding and releasing the above. 2. The cancellation according to claim 1, wherein the cancellation is performed based on a reset operation of the hysteresis operation when the regenerative current of the electric motor after the stop has reached a predetermined negative current. Inverter drive motor device. 3. The reset operation of the hysteresis operation is not performed depending on the regenerative current of the electric motor after the stop, and the cancellation is performed based on the control of the microcomputer that controls the drive of the inverter. The inverter-driven electric motor device according to claim 1.