JPH0467435B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling a power conversion device that obtains a controlled output by pulse width modulating a semiconductor switching element at a high frequency conversion frequency.

[Conventional technology and its problems]

FIG. 3 is a diagram showing a conventional control method for a power conversion device, and FIG. 4 is a diagram showing operating waveforms of each part in FIG. 3. In FIG. 3, the output error signal obtained from the output of the power conversion device via the error amplifier 1 is used as the comparison circuit input signal S ₁ , and the comparison circuit input signal S ₁ and the pulse width control reference signal S ₂ are compared. Comparison is made in circuit 2, and when the comparison circuit input signal S ₁ and pulse width control reference signal S ₂ match as shown in FIG. 4, comparison circuit 2 sends a signal to pulse generator 3. When this signal is applied, the pulse generating circuit 3 sends an off signal _S3 to the semiconductor switching element 4 to turn off the semiconductor switching element 4. However, in this conventional power converter control method, if noise or the like occurs in the output or detection system of the power converter, the noise or the like is superimposed on the comparator circuit input signal S1 via the error amplifier ₁ , and the power converter is This may cause the device to malfunction. Furthermore, if a filter (not shown) consisting of a resistor and a capacitor is inserted between the error amplifier 1 and the comparator circuit 2 in order to remove this noise, there is a drawback that the high-speed response of the power converter cannot be maintained. Ta.

[Means for solving problems]

In order to eliminate the above drawbacks, the present invention integrates the output error signal over approximately one period for each period of the high frequency conversion frequency, holds the integrated value, and compares the held value with a pulse width control reference signal. The present invention provides a method for controlling a power conversion device, which is characterized by controlling the pulse width of a semiconductor switching element.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing operating waveforms of each part of FIG. 1.
In FIG. 1, an output error signal obtained from the output of a power conversion device via an error amplifier 1 is converted into a current by a voltage-current conversion circuit 5, and is integrated over approximately one cycle by an integration circuit 6. The value is held in the hold circuit 7 by the hold pulse signal _S4 from the pulse generator 3, and the obtained hold value is used as the comparator circuit input signal _S1 , and the comparator circuit input signal _S1 and the pulse width control reference signal _S2 The comparator circuit 2 compares the input signal S ₁ with the comparator circuit input signal S 1 as shown in FIG.
The comparison circuit 2 sends a signal to the pulse generation circuit 3 when the pulse width control reference signal S ₂ and the pulse width control reference signal S 2 match.
When this signal is applied, the pulse generator 3 sends an off signal _S3 to the semiconductor switching element 4 to turn off the semiconductor switching element 4. On the other hand, immediately after the above-mentioned integral value is held in the above-mentioned hold circuit 7, an integration reset pulse signal _S5 is sent from the pulse generator 3 to the integration circuit 6, the integration circuit 6 is reset, and the integration is again performed over approximately one cycle. That will happen. In such a control method for a power converter, even if noise occurs in the output or detection system of the power converter, the noise is averaged over the conversion cycle, so the influence of noise can be reduced, and the effects of switching can be reduced. The influence of ripple components can be eliminated. Furthermore, the above can be done while maintaining high-speed response.

FIG. 5 is a diagram showing another embodiment of the present invention, which is a power conversion device that obtains DC output from a three-phase input power source while maintaining the input current of each phase in a sinusoidal waveform. FIG. 6 is a diagram showing operating waveforms of each part in FIG. 5. In FIG. 5, a voltage obtained from the output of the power conversion device via an error amplifier 1 is converted into a current by a voltage-current conversion circuit 5, and is integrated over approximately one cycle by an integrating circuit 6, and the integrated value is A hold pulse signal _S4 from the pulse generator 3 is used to hold the signal in the hold circuit 7. On the other hand, the above hold circuit 7
Immediately after the above integral value is held, an integral reset pulse signal _S5 is sent from the pulse generator 3 to the integrating circuit 6.
is sent, the integration circuit 6 is reset, and integration is again performed over approximately one cycle. Next, the main circuit current flowing through the semiconductor switching element of the high frequency converter 8 is detected by the current detection circuit 9, multiplied by the above-mentioned hold value by the multiplier 10, and converted into a current by the voltage-current conversion circuit 11. The integration circuit 13 (U, V, W) integrates only during the period when the gate circuit 12 (U, V, W) is gated, and the integrated value is used as the comparison circuit input signal S _{1 (U} , _{V , W)} , The comparison circuit input signal S _{1 (U} , _V , _W) and the pulse width control reference signal S _{2 (U} , _V , _W) are connected to the comparison circuit 2 (U, V, W).
When the comparison circuit input signal S _{1 (U} , _V , _W) and the current reference signal S _{2 (U} , _V , _W) match as shown in FIG. U, V, W) send signals to the pulse generation circuit 3. When this signal is applied, the pulse generating circuit 3 sends an off signal to the semiconductor switching element of the high frequency inverter 8.
S _{3 (U} , _V , _W) is sent to turn off the semiconductor switching element, and at the same time, a reset pulse signal S _{6 (U, V, W) is sent to the integrating circuit 13 (U} , _V , _W) to turn off the semiconductor switching element. Instantly resets the integration circuit 13 (U, V, W).
The gate circuit 12 (U, V, W) is gated while the semiconductor switching element of the corresponding high frequency converter 8 is conductive. The semiconductor switching element conducts for a while after the comparison circuit 2 (U, V, W) generates a signal due to a delay in the control circuit, a delay due to the storage time of the semiconductor switching element, etc., but this current is passed through the operation described above. Integrating circuit 13 at
(U, V, W) as the current integral value. Therefore, the current due to the turn-off delay is corrected by determining the pulse width of the next cycle, and the integral value of one cycle of the current flowing through the semiconductor switching element and the current reference control signal S _{2 (U} , _V , _W) are Good linearity can be maintained regardless of the turn-off of the semiconductor switching element or the delay of the off signal. That is, the main circuit current can be controlled while maintaining a good proportional relationship depending on the magnitude of the current reference control signal S _{2 (U} , _V , _W) . The embodiment shown in FIG. 5 has two control inputs, that is, an output error control signal and a current reference control signal, for power control of the power converter, and although power control is possible in any case, the power converter has two control targets. This is especially effective when you have . Other effects are substantially the same as those described in the embodiment shown in FIG. In addition, 14 (U,
V, W) are the gate circuit 12 (U, V, W), the integrating circuit 13 (U, V, W) and the comparison circuit 2 (U,
This is an integral comparison circuit consisting of V, W).

In the embodiment shown in FIG. 5, a plurality of switching elements are controlled in a time-division manner, but the same effect can be obtained even if a plurality of switching elements are controlled simultaneously, that is, multiplexed, using a circuit system.

[Effects of the Invention] As described above, the present invention integrates the output error signal over approximately one period for each period of the high frequency conversion frequency, holds the integrated value, and uses the held value and the pulse width control reference signal. This is a control method for a power conversion device, characterized in that the pulse width of a semiconductor switching element is controlled by comparing the pulse width of the semiconductor switching element. Since the present invention has such characteristics, it is possible to reduce the influence of noise and eliminate the influence of ripples in the conversion period while maintaining high-speed response. Furthermore, when controlling a plurality of semiconductor switching elements, the control balance among the semiconductor switching elements is improved.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing operating waveforms of each part of FIG. 1, FIG. 3 is a diagram showing a conventional control method for a power converter, and FIG. FIG. 5 is a diagram showing another embodiment of the present invention, and FIG. 6 is a diagram showing operating waveforms of each part in FIG. 5. 1...Error amplifier, 2...Comparison circuit, 3...Pulse generator, 4...Semiconductor switching element,
5, 11... Voltage current conversion circuit, 6, 13... Integrating circuit, 7... Hold circuit, 8... High frequency converter, 9... Current detection circuit, 10... Multiplier,
12...gate circuit, 14...integral comparison circuit.

Claims (1)

[Claims] 1. A method for controlling a power conversion device in which at least one semiconductor switching element is switched at a high frequency conversion frequency, and a controlled output is obtained by pulse width modulation using an output error signal, in which the switching element is switched at approximately one period for each period of the high frequency conversion frequency. A power conversion device comprising: integrating the output error signal over the output signal, holding the integrated value, and comparing the held value with a pulse width control reference signal to control the pulse width of the semiconductor switching element. Control method.