JP2862322B2 - Power supply - Google Patents

Description

The present invention relates to a DC power supply circuit that generates a DC output from an AC power supply, and a motor drive circuit that drives a motor with the DC output. In particular, the present invention relates to an input AC power supply. A DC power supply circuit that improves the power factor and simultaneously controls and stabilizes the DC output voltage, the same current, the same power, and the like based on the command value, and
The present invention relates to a motor drive circuit that controls a motor voltage based on a speed command value of the motor.

[Prior Art] In a conventional DC power supply circuit, as described in JP-A-59-198873, a rectified voltage obtained by rectifying an AC power supply by a rectifier circuit is switched by a switching element via a choke coil. A step-up chopper circuit that supplies a switching element end voltage to a smoothing circuit via a diode is employed, and a signal obtained by multiplying an error voltage obtained by comparing an output DC voltage with a reference voltage by the rectified voltage, By modulating the duty ratio of the switching element,
The output DC was stabilized and the power factor was improved at the same time.

[Problems to be Solved by the Invention] In the above-described conventional technology, various noises superimposed on the AC voltage on the rectified voltage and components such as surge voltage due to rectification are mixed in the error voltage to cause a circuit to malfunction. There was a problem.

An object of the present invention is to provide a power supply device capable of improving a power factor without detecting the rectified voltage, and simultaneously controlling and stabilizing an output voltage, a current, a power, and the like.

[Means for Solving the Problems] In order to solve the above problems, the present invention generates the error voltage by an arithmetic means such as a microcomputer in the boost chopper circuit, and further calculates the error voltage from the error voltage when the switching element is used. A ratio control coefficient is calculated, and a duty ratio of the switching element is controlled by a signal obtained by multiplying the current ratio control coefficient by the rectified current value, thereby controlling an output DC voltage to improve a power factor. .

The error current is calculated from the output current and the current command value (reference current), and the output power and the power command value (reference power) are calculated.
Error power is further calculated, and these error currents, error powers, and the like are replaced with the above-described error voltages. Similarly, the output DC current or output power is controlled, and at the same time, the power factor is improved.

Furthermore, in order to stabilize the operation of the power supply circuit, a proportional and integral element is introduced in a control loop of the output voltage or the same current or the same power to calculate the duty ratio control coefficient to improve the dynamic characteristics. .

The proportional and integral elements are a component P proportional to a value obtained by dividing each error by the output voltage in the arithmetic means.
And a component I proportional to the integral are calculated and generated.

The duty ratio control coefficient is generated so as to be proportional to the reciprocal of the addition signal E of P and I or (1-E). If necessary, the peak voltage of the AC power supply, the effective value, etc. To be generated.

Further, the output DC voltage when the load is cut off from the smoothing circuit is detected as the peak voltage of the AC power supply voltage, and the AC power supply voltage detection circuit is omitted.

Further, the peak voltage or the effective value of the AC power supply is set in a storage device in the arithmetic circuit in advance, so that the load cutoff circuit is omitted.

When the synchronous motor is driven by the power supply device of the present invention, the rotational speed of the synchronous motor is calculated from the commutation position signal of the synchronous motor, and is proportional to the deviation between the rotational speed signal and the reference speed command value. And the signal obtained by performing the integral operation is used to calculate the voltage command value, thereby controlling the rotation speed of the synchronous motor and simultaneously improving the power factor.

[Operation] The power supply device of the present invention configured as described above controls the duty ratio of the switching element (chopper) of the boost chopper type power supply circuit according to the rectified current waveform to improve the power factor.

Further, the duty ratio is controlled by a deviation value between an output value and a command value to stabilize output values such as voltage, current, and power.

Further, the response value is stabilized by performing a proportional and integral operation on the deviation value.

Further, when a synchronous motor is connected to the power supply device of the present invention, the duty ratio is controlled by the deviation between the rotational speed of the synchronous motor and the speed command value, thereby stabilizing the rotational speed.

Embodiment First, the operation principle of the present invention will be described with reference to FIG.

The circuit shown in the upper part of FIG.
A known step-up chopper circuit that switches a rectified voltage obtained by rectification by a switching element 32 through an inductor 31 and smoothes the switching element end voltage by a smoothing capacitor 4 through a diode 33 and supplies it to a load 5. It is. Incidentally, reference numeral 61 denotes a resistance element for detecting a rectified current.

In the boost chopper circuit, the switching element 32
Assuming that the switching period is T, the ON time is T ₁ , the OFF time is T ₂ , the inductance value of the inductor 31 is L, and the voltage of the AC power supply 1 is v ₁ , the output voltage applied to the load 5 is Vo = Vo (T / T ₂ ) v ₁ (1) However, the T is made sufficiently shorter than the period of v _1.

When the rectified current, that is, the current detected by the resistance element 61 is defined as i and the OFF ratio (T ₂ / T) is made proportional to the current i as shown in Expression (2), the output voltage Vo becomes T ₂ / T = A ₁ i (2) A ₁ = proportional coefficient Vo = v ₁ / (A ₁ i) (3)

From equation (3), Vo is a DC voltage with a negligible time variation, and thus (v ₁ / i) = constant (4).

From this, it can be seen that the waveforms of the current i and the voltage v ₁ (for example, a commercial frequency AC voltage) are similar, and the phases are in phase. That is, the best power factor 1 can be obtained by making the OFF ratio (T ₂ / T) proportional to the rectified current i.

 Next, the control principle of the output voltage Vo will be described.

From equation (1), the output voltage Vo is the reciprocal of the OFF ratio (T / T ₂ )
Therefore, the output voltage Vo is controlled by an error voltage e obtained by comparing the output voltage Vo with the reference voltage Vr.

e = Vr−Vo (5) That is, since T / T ₂ = 1 / (A ₁ i) according to the equation (2), this is calculated as T / T ₂ = A ₂ e / (A ₁ i) (6) Equation (1) gives Vo = (v ₁ / i) (A ₂ / A ₁ ) (Vr−Vo). Becomes A ₂ is a constant, typically corresponds to the gain of the error amplifier. Also, Corresponds to a loop gain, and if this is sufficiently large, equation (7) becomes Vo = Vr (8), and the output voltage Vo is fixed to the reference voltage Vr.

FIGS. 1 to 3 are diagrams showing a first embodiment of the present invention based on the above control principle.

In FIG. 1, the rectified current is detected by a current detection circuit 6, and the output DC voltage is detected by a voltage detection circuit 8 and input to a microcomputer 9.

The microcomputer 9 has an output Vo and a DC voltage command value Vr.
The proportional coefficient K is generated from the error voltage e obtained by comparing

In addition, the multiplication circuit 63 receives the rectified current signal A ₁ i detected by the resistance element 61 and amplified by the amplifier 62,
This is multiplied by the proportional coefficient K to output a signal. That is, the output V ₂ of the multiplication circuit 63 is given by V ₂ = KA ₁ i (9).

V ₂ is the reciprocal of equation (6), that is, the OFF ratio (T ₂ /
T).

As is well known, the feedback control system calls it PID,
Processes such as proportional (P), integral (I), and derivative (D) are added to the error voltage e (= Vo−Vr), and these are combined as necessary and fed back to improve the responsiveness of the system. Is done.

When only P is applied, the value of K becomes K = 1 / (A ₂ e) (10), and when the proportional component P and the same integral component I of e are used, K = 1 / (P + I) (11)

Note that (P + I) is referred to as a virtual error E.

On the other hand, the loop gain (v ₁ / i) (A ₂ / A
₁₎ Since varies depending on the size of the AC voltage v _1, as shown in equation in order to remove the influence of this variation (12) (13), the amplitude V ₁ or the effective value of the AC voltage v ₁ in the K It should be good to multiply by.

K = V ₁ / (A ₂ e) (12) K = V ₁ / (P + I) (13) The processing V ₂ of the multiplier 63 is applied to the comparator 72 in the switching signal circuit 7 and The output is compared with the output to generate a rectangular wave signal for switching. The rectangular signal is applied to the switching transistor 32 via the driver 71.

When the maximum value of the output voltage V ₂ of the multiplier circuit 63 is set equal to the maximum value V _H of the output of the triangular wave generator 73, the transistor 32
The OFF ratio (T ₂ / T) is T ₂ / T = V ₂ / V _H (14).

The OFF ratio changes in proportion to the rectified current i, and its magnitude is controlled in proportion to the error voltage, the virtual error voltage, etc., so that the output DC voltage Vo is stabilized, and Power factor value is obtained.

Also, from FIG. 1, the above V ₂ , that is, the off-time ratio (T ₂ / T)
Is the output (A ₁ i) of the amplifier 62 and the microcomputer 9
T ₂ / T = A ₁ ik (15) Substituting this into equation (1) gives Vo = v ₁ / (A ₁ ik) (16), and obtaining k from this gives k = v ₁ / (A ₁ iVo) (17).

Comparing equation (17) with equation (12) or (13) shows that i in equation (17) may be replaced with a virtual current proportional to the error signal e or (P + I). However, in this case, v ₁ is simultaneously replaced with a voltage having no pulsation such as the amplitude value of the input voltage. The microcomputer 9 calculates the virtual current from the error signal, and further calculates k from the virtual current, the amplitude of the input voltage, the output voltage, and the like.

FIG. 2 shows K of the equation (13) performed by the microcomputer 9.
5 is a flowchart showing the calculation means.

In step S1, the microcomputer 9 takes in the output DC voltage Vo and the DC voltage command value (reference voltage) Vr,
In step S2, the proportional term P is calculated from the error voltage (Vr−Vo).
And an integral term I are generated, and the two are added to produce a virtual error E
Generate Here, the proportional term P is given by K _P (Vr−Vo). I is generated by adding K _I (Vr−Vo) to the integral term I ₁ at that time. K _P and K _I are ratio coefficients.

In step S3, the proportional coefficient K is calculated using the above E.

K = V ₁ / E (18) where V ₁ is the peak voltage of the AC power supply 1. Also,
This proportional coefficient K may be obtained from equation (17).

It said V ₁ was able to detect the output DC voltage Vo when blocks the transistor 32, the load 5 is removed, or lightly.

In the next step S4, the microcomputer 9 sets the K
Is output.

Since the equation (18) includes the division by the virtual error E, there is a problem that the number of processing steps in the microcomputer 9 is large, and practically, it is desired to make an operation excluding the above division.

FIG. 3 is a flowchart in the case where 1 / in the above equation (18) is linearly approximated as in equation (19).

1 / E ≒ 1-E (19) FIG. 4 is a diagram showing the configuration of the second embodiment of the present invention.

4 is different from FIG. 1 in that a maximum current ratio command generating circuit 75 and an operational amplifier 74 are added to the control circuit 7. In FIG. 4, if the resistance value of the resistor 61 is R, the current flowing through the resistor 61 is i, the output voltage of the multiplying circuit 63 is V ₂ , and the output voltage of the maximum current ratio command generating circuit 75 is Vc, the operational amplifier 74 The output V ₇₄ is V ₇₄ = Vc−V ₂ .

Here, the maximum and the output V _H equal ON distribution ratio D ₁ of the above Vc and the triangular wave generator 73 is given by _{D 1 = V 74 / V H} .

The program necessary for the above calculation is stored in the microcomputer 9 as in the case of FIG. 1, whereby the output DC voltage is stabilized, and at the same time, it operates so as to keep the power factor at substantially 1.

FIG. 5 shows a third embodiment of the present invention in which the circuit configuration of FIG. 4 is applied to speed control of a three-phase synchronous motor 18 for driving a compressor 19.

In FIG. 5, the DC output voltage Vo and the power factor are controlled in the same manner as in FIG.

The three-phase synchronous motor 18 has switching transistors TR1 to TR
Driven by an inverter circuit consisting of R6. The position detection circuit 21 detects the rotational position of the rotor of the synchronous motor 18, generates position signals 22 corresponding to each of the three phases, and inputs the position signals 22 to the microcomputer 9.

The microcomputer 9 is a synchronous motor based on the position signal 22.
A drive signal 18 is generated and input to the driver 17 of the inverter circuit. At the same time, the synchronous motor 18
Is calculated and compared with the speed command 24, the proportional coefficient K is calculated according to the comparison result to control the DC output voltage Vo,
Thereby, the output of the synchronous motor 19 is controlled.

FIG. 6 is a waveform example of the three-phase component of the position signal 22,
The components of the three phases are mutually shifted by 60 ° with one cycle being 360 °. The period T corresponding to the rotation speed of the synchronous motor 18 is calculated by measuring the times t ₁ to t ₆ corresponding to the above-mentioned 60 °.

FIG. 7 is a flowchart showing the speed control processing performed by the microcomputer 9.

In step S7, the microcomputer 9 calculates the command speed Nr from the speed command, calculates the cycle T from the position signal 22 in step S8, and calculates the speed N using the speed conversion coefficient Ky in step S9.

Next, in step S10, the speed error ΔN (= Nr−
Generates a proportional term P _N and the integral term I _N than N), the generating a DC voltage command value Vr by adding both. Where the proportional term P
Is given by P _N = K _P ΔN (20) Also, I _N is generated by adding the K _I .DELTA.N the integral term of the time. K _P and K _I are proportional coefficients.

In step S11, a proportional term P and an integral term I are generated from the deviation (Vr-Vo) between the DC voltage command value Vr and the output DC voltage Vo, and the two are added to generate a virtual error E.
Here, the proportional term P is given by P = K _P (Vr−Vo) (21) Also, I is K _I (Vr−
Vo) is generated. K _P and K _I are proportional coefficients.

In step S13, the proportional coefficient K is calculated using E.

K = Vs / (IsVr) (22) In the next step S14, the microcomputer 9 outputs the above K.

By repeating the above speed control processing, the DC output voltage Vo is controlled, and the detected speed N becomes equal to the command speed Nr.

In the embodiment of the present invention shown in FIGS. 5 to 7, the DC voltage command Vr is obtained from the speed error, and the proportional coefficient K is calculated so that the DC output voltage Vo matches the above Vr. Alternatively, the proportional coefficient K may be directly calculated from the calculated value.

FIG. 8 is a block diagram of a fourth embodiment of the present invention for controlling the load current of the DC power supply.

The load current is detected by the resistor 141, amplified by the amplifier 142, and input to the microcomputer 9.

The microcomputer 9 generates a virtual error from the deviation between the DC current detection value and the DC current command, and further calculates a proportional coefficient K from the virtual current command. Further, the proportional coefficient K
And the rectified current detection value detected by the resistor 61 and the transistor
Calculate the duty ratio of 32.

The programs necessary for each of the above operations are stored in the microcomputer 9 as in the case of FIG. 1, whereby the output DC voltage is stabilized, and at the same time, the operation is performed so as to keep the power factor at approximately 1.

FIG. 9 is a block diagram of a fourth embodiment of the present invention for controlling the output power of a DC power supply.

In order to detect the output power in FIG.
The microcomputer 9 receives the output current detected by the DC current detection circuit 14 including the amplifier 142 and the output voltage detected by the DC voltage detection circuit 8 and multiplies the two by the two to calculate the output power.

The microcomputer 9 executes processing such as generating a virtual error from the deviation between the output power and the DC power command value, further calculating a proportional coefficient K from the virtual error, and inputting this to the multiplication circuit 6. The other parts in FIG. 9 operate in the same manner as in FIG.

With the above operation, the output power can be controlled, and at the same time, the power factor can be improved.

[Effects of the Invention] According to the present invention, the power factor of the step-up chopper type power supply circuit can be made close to the ideal value of 1, without detecting the input AC power supply voltage.

Further, simultaneously with the improvement of the power factor, the output values of the voltage, current, power and the like can be controlled and stabilized according to the command value.

Further, the response characteristics can be stabilized by performing the proportional and integral operations on the control deviation.

Furthermore, the synchronous motor can be driven by the power supply device of the present invention to improve the duty ratio and at the same time control and stabilize the rotational speed of the synchronous motor according to the speed command value.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a voltage control type power supply circuit according to a first embodiment of the present invention, FIGS. 2 and 3 are flowcharts each explaining the operation of FIG. 1, and FIG. 4 is a second embodiment of the present invention. FIG. 5 is a voltage control type power supply circuit diagram of an embodiment, FIG. 5 is a synchronous motor control circuit diagram of a third embodiment of the present invention, FIG. 6 is a conduction phase diagram of the synchronous motor, and FIG. FIG. 8 is a flow chart for explaining the operation, FIG. 8 is a current control type power supply circuit diagram according to a fourth embodiment of the present invention, and FIG. 9 is a power control type power supply circuit diagram according to a fifth embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... AC power supply 2 ... Rectifier circuit 3 ... Power factor improvement circuit 31 ... Choke coil 32 ... Switching transistor 4 ... Capacitor 5 ... Load 6 ... Current detection circuit 62, an amplifier, 63, a multiplying circuit, 7, a control circuit, 72, a comparator, 72, a triangular wave generator, 74
... operational amplifier, 8 ... voltage detection circuit, 9 ... microcomputer, 14 ... DC current detection circuit.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-56-166765 (JP, A) JP-A-2-241365 (JP, A) JP-A-3-277172 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) H02M 3/00-3/44 H02M 7/00-7/40

Claims (9)

(57) [Claims] A rectified voltage obtained by rectifying an AC power supply by a rectifier circuit is switched by a switching element via a choke coil, and the switching element terminal voltage is supplied to a smoothing circuit via a diode, and is supplied to the smoothing circuit. In a boost chopper circuit for connecting a load, a means for detecting a rectified current of the rectifier circuit, a means for detecting a voltage, current, or power of the load, a command value generating means, a load voltage, a load current, or a load power Means for generating a deviation value E between the rectified current value and the command value; calculating means for calculating a duty ratio control coefficient of the switching element proportional to the reciprocal of the E or (1-E); A duty ratio control coefficient multiplication circuit; and a duty ratio control circuit that controls the duty ratio of the switching element based on the output of the multiplication circuit. A power supply device characterized by the following. 2. A rectified voltage obtained by rectifying an AC power supply by a rectifier circuit is switched by a switching element via a choke coil, and the switching element terminal voltage is supplied to a smoothing circuit via a diode, and is supplied to the smoothing circuit. In a boost chopper circuit for connecting a load, a means for detecting a rectified current of the rectifier circuit, a means for detecting a voltage, current, or power of the load, a command value generating means, a load voltage, a load current, or a load power Means for generating a deviation value E between the command and the command value, a proportional term P proportional to the deviation value E, and an integral term I proportional to the integral of the deviation value are calculated, and the P and I are added. Means for generating a virtual error E1, and the reciprocal of E1 or (1
-E1) a calculating means for calculating the duty ratio control coefficient, a multiplying circuit of the rectified current value and the duty ratio control coefficient, and a duty ratio of the switching element controlled by an output of the multiplier circuit. A power supply device comprising a duty ratio control circuit. 3. The method according to claim 1, wherein said calculating means includes means for multiplying said current ratio control coefficient by a voltage value of said AC power supply and dividing by said load voltage value. Power supply. 4. The apparatus according to claim 1, further comprising means for controlling connection between said load and said smoothing circuit.
A power supply unit configured to input the smoothing circuit output voltage obtained by shutting down the load during the switching operation of the boost chopper circuit by the connection control unit to the arithmetic circuit as the AC power supply voltage; . 5. The power supply device according to claim 1, wherein the arithmetic circuit includes a storage device for storing the AC power supply voltage value. 6. A rectification voltage obtained by rectifying an AC power supply by a rectification circuit is switched by a switching element through a choke coil, and the switching element terminal voltage is supplied to a smoothing circuit through a diode, and is supplied to the smoothing circuit. In a step-up chopper circuit type motor power supply device to which a synchronous motor driving inverter circuit is connected, a means for detecting a rectified current of the rectifier circuit, a means for detecting an output voltage of the smoothing circuit, a speed command value generating means,
Calculate the DC voltage command value from the commutation position detection circuit of the synchronous motor and the output voltage of the commutation position detection circuit, and further calculate the duty ratio control coefficient of the switching element from the DC voltage command value and the output voltage of the smoothing circuit. Calculating means for calculating;
A multiplication circuit of the rectified current value and the duty ratio control coefficient,
A power ratio control circuit for controlling a duty ratio of the switching element based on an output of the multiplication circuit. 7. The synchronous motor according to claim 6, wherein the calculating means calculates at least a rotational speed N of the synchronous motor from a commutation position signal cycle of the synchronous motor, and calculates the rotational speed N and the speed command value Nr. Means for calculating a proportional term Pn proportional to the deviation value of the above and an integral term In proportional to the integral of the speed deviation value, and adding the Pn and In to generate a DC voltage command Vr; and the smoothing circuit. A proportional term P proportional to a deviation value between the output voltage and the DC voltage command value Vr and an integral term I proportional to the integral of the deviation value are calculated.
And a means for generating a virtual error E by adding I and I, and means for generating the conduction ratio control coefficient by multiplying the AC power supply voltage by E and dividing the smoothing circuit voltage. A power supply device characterized by: 8. The synchronous motor driving device according to claim 7, further comprising means for controlling a connection between said synchronous motor driving inverter circuit and said smoothing circuit, wherein said connection control means stops switching operation of said step-up chopper circuit. Wherein the output voltage of the smoothing circuit obtained by cutting off the inverter circuit is input to the arithmetic circuit as the AC power supply voltage. 9. The power supply device according to claim 7, wherein the arithmetic circuit includes a storage device for storing the AC power supply voltage value.