CA1185320A - Circuit arrangement for controlling electric drive units - Google Patents
Circuit arrangement for controlling electric drive unitsInfo
- Publication number
- CA1185320A CA1185320A CA000392543A CA392543A CA1185320A CA 1185320 A CA1185320 A CA 1185320A CA 000392543 A CA000392543 A CA 000392543A CA 392543 A CA392543 A CA 392543A CA 1185320 A CA1185320 A CA 1185320A
- Authority
- CA
- Canada
- Prior art keywords
- circuit
- inverter
- voltage
- store
- output
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000006243 chemical reaction Methods 0.000 claims description 5
- 230000001419 dependent effect Effects 0.000 abstract description 3
- 230000001276 controlling effect Effects 0.000 description 7
- 238000010586 diagram Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 2
- 230000001133 acceleration Effects 0.000 description 1
- QHGVXILFMXYDRS-UHFFFAOYSA-N pyraclofos Chemical compound C1=C(OP(=O)(OCC)SCCC)C=NN1C1=CC=C(Cl)C=C1 QHGVXILFMXYDRS-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
- H02M7/42—Conversion of DC power input into AC power output without possibility of reversal
- H02M7/44—Conversion of DC power input into AC power output without possibility of reversal by static converters
- H02M7/48—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
- H02M7/53871—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
- H02M7/53873—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current with digital control
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Inverter Devices (AREA)
- Control Of Ac Motors In General (AREA)
- Dc-Dc Converters (AREA)
Abstract
ABSTRACT
A circuit for controlling the speed of electric drives, whose output produces alternating current at a voltage and frequency appropriate to the particular drive for best efficiency, comprises an inverter driven from a variable d.c. supply (typically derived from the A.C. mains power). A desired input value, which may be a voltage or a frequency signal, controls a store containing the control values for the d.c. supply, which are output in accordance with the value of the input signal, to control the voltage output of the inverter. The desired input value signal also controls a further store whose read out speed is dependent upon the input value signal, and which thus determines the frequency of output of the inverter. Selection means allow only certain of the stored values to be used as appropriate to the drive which the inverter is to feed. The store for the d.c. supply feeds a digital to analogue circuit so that analogue control signals are fed to the d.c. supply.
A circuit for controlling the speed of electric drives, whose output produces alternating current at a voltage and frequency appropriate to the particular drive for best efficiency, comprises an inverter driven from a variable d.c. supply (typically derived from the A.C. mains power). A desired input value, which may be a voltage or a frequency signal, controls a store containing the control values for the d.c. supply, which are output in accordance with the value of the input signal, to control the voltage output of the inverter. The desired input value signal also controls a further store whose read out speed is dependent upon the input value signal, and which thus determines the frequency of output of the inverter. Selection means allow only certain of the stored values to be used as appropriate to the drive which the inverter is to feed. The store for the d.c. supply feeds a digital to analogue circuit so that analogue control signals are fed to the d.c. supply.
Description
~ ~35~
CIRCUIT EOR CONTROLLING El.ECTRIG DRIVES
The invention relates to a circuit for controlling electric drives, including an alternating current rectifier, a d.c. controller and an alternating current inverter driven from an electronic control circuit.
When controlling the speed of alternating current drives, use is conventionally made of frequency inverters, since they enable the speed to be controlled with little lossO Distortion must be the minimum possible in the output vol tage of the inverter over the whole speed range, and moreover the ratio between the output voltage of the inverter and its frequency must stand in a relationship which is specific for the particular speed control. Optimum energy utilisation is pbssible only if both conditions are met.
The known circuits for controlling the speed of electric drives use electronic step switches which, by special control of such switches, produce the required output voltage from the inverter. Complicated switching processes must take place in the step switches, for which can be used, for example, distributors, shift registers, counters or other equivalent quasi-dynamic step switchesO
3~
A very complicated circuit is therefore required to meet the demands of this quasl-dynamic system. However, the quasl-dynamlc nature in ltself has a negative efect on the dlstortion in the output voltage p~oduced, over the whole frequency range ~speed range).
Since the distortion creates a deterloration in energy conversion because, for example, the energy con-verted into heat in an electric motor is directly pro-portional to the distortion, such voltage arrangements are not suitable for applications requiring optimum utilisation of energy, for example, heat pumps~
As already mentioned, the optimum conversion of electric energy in~o dynamic energy also depends on the ratio between the output voltage produced by an inverter and its frequency. In many appllcations, such ratio is primarily linear, and in the Known circuits for con-trolling electrlc drives there is a possibility of slightly influencing the voltage-frequency ratio at the top and/or bottom end of the speed range. In this way an attempt is made to meet the requirements of any particular application to some extent. In the case of certain electric drives such as, for example, heat pump drives or circulating and delivery pump drives, the vol~age-frequency ratio is basically non-linear (e.g. cubic in the case of a fan drive), so that the known methods for adapt~ng the voltage-;~
3~3~
frequency ratio of an inverter are completely inadequatefor that of the particular application. Due to its poor utilisation of energy, a controllabl~ drive operated in this way is completely uneconomic and therefore un-satisfactory.
I~ is therefore an object of the invention to provide a circuit for controlling electric drives with the optimum util isation of energy.
According to the invention there is provided a circuit for controlling an electxic drive, comprising an alternating current rectifier connected to a d.c.
controller which is connected to an alternating current inverter driven from an electronic control circuit, wherein a desired input value for the electric drive, converted by an analog-to-digital converter, addresses a store the particular addresses of which contain control values which ~re proportional to the output voltages of the inverter, and a respective desired output value is fed from the store after conversion in a digital-to-analog converter to the controller as a desired control value.
The new circuit makes it possible to store in the store, for example a read only memory, a number of desired values representing the voltage-frequency ratio, and to select such a ratio by a selector for the operation of an electric drive.
The d.c controller can be constructed as a voltage controller and receive the desired voltage value of the alternating current inverter from the Aigital-to-analog ~,,~
)3~2~
converter.
The control circuit of the alternating current inverter can have a further store which delivers control signals for the inverter and whose read-out spee~ is derived from the desired input value representing the required frequency outpu~ of the voltage-frequency ratio.
The control circuit embodying the invention will now be explained in greater detail with reference to the accompanying drawings, wherein:-Figure l is a circuit diagram, and Figure 2 is a graph.
The circuit diagram (Figure 13 partly in the form ofa block diagram, consists of an alternating current (three phase) rectifier 1 which feeds an alternating current (three phase) inverter 3 through a d.c. voltage controller 2. The alternating current inverter 3 comprises six n-p-n transistors 4, which are disposed in pairs with their collector-emitter paths in series, each pair shunted across the output voltage of the d.c. controller 2. Each of the three connecting points of the emitter of a transistor to the collector of another transistor of a pair forms an output U,V,W of the alternating current inverter 3. A driver stage 5 has six outputs ~O to Q5 which control the base electrcdes of the six transistors (4), so that alternating current with a frequency dependent on ~he operation of the transistors and an amplitude dependent on the output voltage of the d.c. controller 2 is produced at the outputs U,V,W.
~353~
The driver stage 5 is controlled by six outputs QO to Q5 of a fixed value store 6, whose read-out speed can in turn be controlled by outputs QO to Q3 of a counter 7.
A selector a enables partlcular addresses Of the fixed value store 6 to be selected for calling up, so that particular wave shapes can be selected for the output voltage to be produced. The counter 7 is supplied with signals from a voltage-frequency converter 9 ~which receives a desired input voltage Vin) or a desired frequency input Fin, respectively.
Of primary concern is the control circuit of the d.c. controller 2, which will now be described. For this purpose a fixed value store 10 stores a number of voltage-frequency ratios of particular electric drives, which can b~ selected by a selector 11.
The store 10 is addressed via outputs QO to Q7 o~ an analog-to-digital converter 12 which is controlled by the output signal of a frequency-voltage converter 13 fed with input Fin. As a result, in dependence on selection by the selector 11, dlgital data is available at outputs QO to Q7 of the store 10, which outputs pass via a digital~to-analog converter 14 as a desired voltage input to the voltage controller 2 supplied with the actual voltage value. In thls way the data of a number of voltage-frequency ratios can be stored in the store 10 and as a result a number of i3~g~
characteristics are avallable for the optimum acceleration and/or deceleration of the particular electric drive to be controlled. However, in addition to voltage control, it is also posslble to control the load current and/or the power of the particular drive. The aforementioned signals Fin and in act on the circuit in similar manner to a super-ordinate control.
As can be seen from the graph (Figure 2) electric drives may have very different voltage~frequency ratios.
In the graph, voltage is plotted on the ordinate, the frequency being plotted on the abscissa. A curve 20 .Indlcates that for a fan, while a curve 21 indicates that for a typical heat pump-electric motor. The circuit therefore enables the characteristics to be broken up into 2n portions 22 whose voltage values correspond to the data contained in the store 10. ~he result is an ~ppreciably improved utillsation of energy in the conversion of electric energy lnto dynamic energy, distortion of the output voltage produced belng considerably reduced by the cont,rol circui~
embodying the invention.
CIRCUIT EOR CONTROLLING El.ECTRIG DRIVES
The invention relates to a circuit for controlling electric drives, including an alternating current rectifier, a d.c. controller and an alternating current inverter driven from an electronic control circuit.
When controlling the speed of alternating current drives, use is conventionally made of frequency inverters, since they enable the speed to be controlled with little lossO Distortion must be the minimum possible in the output vol tage of the inverter over the whole speed range, and moreover the ratio between the output voltage of the inverter and its frequency must stand in a relationship which is specific for the particular speed control. Optimum energy utilisation is pbssible only if both conditions are met.
The known circuits for controlling the speed of electric drives use electronic step switches which, by special control of such switches, produce the required output voltage from the inverter. Complicated switching processes must take place in the step switches, for which can be used, for example, distributors, shift registers, counters or other equivalent quasi-dynamic step switchesO
3~
A very complicated circuit is therefore required to meet the demands of this quasl-dynamic system. However, the quasl-dynamlc nature in ltself has a negative efect on the dlstortion in the output voltage p~oduced, over the whole frequency range ~speed range).
Since the distortion creates a deterloration in energy conversion because, for example, the energy con-verted into heat in an electric motor is directly pro-portional to the distortion, such voltage arrangements are not suitable for applications requiring optimum utilisation of energy, for example, heat pumps~
As already mentioned, the optimum conversion of electric energy in~o dynamic energy also depends on the ratio between the output voltage produced by an inverter and its frequency. In many appllcations, such ratio is primarily linear, and in the Known circuits for con-trolling electrlc drives there is a possibility of slightly influencing the voltage-frequency ratio at the top and/or bottom end of the speed range. In this way an attempt is made to meet the requirements of any particular application to some extent. In the case of certain electric drives such as, for example, heat pump drives or circulating and delivery pump drives, the vol~age-frequency ratio is basically non-linear (e.g. cubic in the case of a fan drive), so that the known methods for adapt~ng the voltage-;~
3~3~
frequency ratio of an inverter are completely inadequatefor that of the particular application. Due to its poor utilisation of energy, a controllabl~ drive operated in this way is completely uneconomic and therefore un-satisfactory.
I~ is therefore an object of the invention to provide a circuit for controlling electric drives with the optimum util isation of energy.
According to the invention there is provided a circuit for controlling an electxic drive, comprising an alternating current rectifier connected to a d.c.
controller which is connected to an alternating current inverter driven from an electronic control circuit, wherein a desired input value for the electric drive, converted by an analog-to-digital converter, addresses a store the particular addresses of which contain control values which ~re proportional to the output voltages of the inverter, and a respective desired output value is fed from the store after conversion in a digital-to-analog converter to the controller as a desired control value.
The new circuit makes it possible to store in the store, for example a read only memory, a number of desired values representing the voltage-frequency ratio, and to select such a ratio by a selector for the operation of an electric drive.
The d.c controller can be constructed as a voltage controller and receive the desired voltage value of the alternating current inverter from the Aigital-to-analog ~,,~
)3~2~
converter.
The control circuit of the alternating current inverter can have a further store which delivers control signals for the inverter and whose read-out spee~ is derived from the desired input value representing the required frequency outpu~ of the voltage-frequency ratio.
The control circuit embodying the invention will now be explained in greater detail with reference to the accompanying drawings, wherein:-Figure l is a circuit diagram, and Figure 2 is a graph.
The circuit diagram (Figure 13 partly in the form ofa block diagram, consists of an alternating current (three phase) rectifier 1 which feeds an alternating current (three phase) inverter 3 through a d.c. voltage controller 2. The alternating current inverter 3 comprises six n-p-n transistors 4, which are disposed in pairs with their collector-emitter paths in series, each pair shunted across the output voltage of the d.c. controller 2. Each of the three connecting points of the emitter of a transistor to the collector of another transistor of a pair forms an output U,V,W of the alternating current inverter 3. A driver stage 5 has six outputs ~O to Q5 which control the base electrcdes of the six transistors (4), so that alternating current with a frequency dependent on ~he operation of the transistors and an amplitude dependent on the output voltage of the d.c. controller 2 is produced at the outputs U,V,W.
~353~
The driver stage 5 is controlled by six outputs QO to Q5 of a fixed value store 6, whose read-out speed can in turn be controlled by outputs QO to Q3 of a counter 7.
A selector a enables partlcular addresses Of the fixed value store 6 to be selected for calling up, so that particular wave shapes can be selected for the output voltage to be produced. The counter 7 is supplied with signals from a voltage-frequency converter 9 ~which receives a desired input voltage Vin) or a desired frequency input Fin, respectively.
Of primary concern is the control circuit of the d.c. controller 2, which will now be described. For this purpose a fixed value store 10 stores a number of voltage-frequency ratios of particular electric drives, which can b~ selected by a selector 11.
The store 10 is addressed via outputs QO to Q7 o~ an analog-to-digital converter 12 which is controlled by the output signal of a frequency-voltage converter 13 fed with input Fin. As a result, in dependence on selection by the selector 11, dlgital data is available at outputs QO to Q7 of the store 10, which outputs pass via a digital~to-analog converter 14 as a desired voltage input to the voltage controller 2 supplied with the actual voltage value. In thls way the data of a number of voltage-frequency ratios can be stored in the store 10 and as a result a number of i3~g~
characteristics are avallable for the optimum acceleration and/or deceleration of the particular electric drive to be controlled. However, in addition to voltage control, it is also posslble to control the load current and/or the power of the particular drive. The aforementioned signals Fin and in act on the circuit in similar manner to a super-ordinate control.
As can be seen from the graph (Figure 2) electric drives may have very different voltage~frequency ratios.
In the graph, voltage is plotted on the ordinate, the frequency being plotted on the abscissa. A curve 20 .Indlcates that for a fan, while a curve 21 indicates that for a typical heat pump-electric motor. The circuit therefore enables the characteristics to be broken up into 2n portions 22 whose voltage values correspond to the data contained in the store 10. ~he result is an ~ppreciably improved utillsation of energy in the conversion of electric energy lnto dynamic energy, distortion of the output voltage produced belng considerably reduced by the cont,rol circui~
embodying the invention.
Claims (6)
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. a circuit for controlling an electric drive, comprising an alternating current rectifier connected to a d.c. controller which is connected to an alternating current inverter driven from an electronic control circuit, wherein a desired input value for the electric drive, converted by an analog-to-digital converter, addresses a store the particular addresses of which contain control values which Are proportional to the output voltages of the inverter, and a respective desired output value is fad from the store after conversion in a digital-to-analog converter to the controller as a desired control value.
2. A circuit as defined in claim 1, wherein the desired control value represents the voltage-frequency ratio of the electric drive.
3. A circuit as defined in claim 2, wherein a number of voltage-frequency ratios of particular electric drives, are carried in said store and selection means for selecting some of said number of ratios.
4. A circuit as defined in claims 1, 2 or 3, wherein the store is a read only memory.
5. A circuit as defined in claim 1, 2 or 3, wherein the controller takes the form of a d. c. voltage controller, and the desired control value fed by the digital-to-analog converter to the voltage controller represents the desired value of the output voltage of the alternating current inverter.
6. A circuit as defined in claim 1, 2 or 3 wherein the electronic control circuit of the alternating current inverter has a further store, which delivers control signals for the inverter and whose read-out speed is derived from the desired input value to provide desired frequency output from said inverter.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3100821A DE3100821A1 (en) | 1981-01-14 | 1981-01-14 | "CIRCUIT ARRANGEMENT FOR CONTROLLING ELECTRICAL DRIVES" |
| DEP3100821.6 | 1981-01-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1185320A true CA1185320A (en) | 1985-04-09 |
Family
ID=6122534
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000392543A Expired CA1185320A (en) | 1981-01-14 | 1981-12-17 | Circuit arrangement for controlling electric drive units |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS57129172A (en) |
| CA (1) | CA1185320A (en) |
| DE (1) | DE3100821A1 (en) |
| DK (1) | DK282A (en) |
| FR (1) | FR2498029B1 (en) |
| GB (1) | GB2091052B (en) |
| SE (1) | SE8107251L (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3016545A1 (en) * | 1980-04-29 | 1981-11-05 | Emil Weber Fabrik für Ölhydraulik GmbH & Co, 7129 Güglingen | HYDRAULIC LOCKING UNIT FOR LOCKING TILTABLE CABS OF TRUCKS |
| GB2111326B (en) * | 1981-12-01 | 1985-07-24 | Chloride Group Ltd | No-break power supply |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3766431A (en) * | 1967-10-23 | 1973-10-16 | Thorn Electrical Ind Ltd | A lighting control system including an analogue to digital converter |
| US4320331A (en) * | 1979-10-01 | 1982-03-16 | General Electric Company | Transistorized current controlled pulse width modulated inverter machine drive system |
-
1981
- 1981-01-14 DE DE3100821A patent/DE3100821A1/en not_active Withdrawn
- 1981-12-03 SE SE8107251A patent/SE8107251L/en not_active Application Discontinuation
- 1981-12-17 CA CA000392543A patent/CA1185320A/en not_active Expired
- 1981-12-18 JP JP56203848A patent/JPS57129172A/en active Pending
-
1982
- 1982-01-04 DK DK282A patent/DK282A/en not_active Application Discontinuation
- 1982-01-12 FR FR8200349A patent/FR2498029B1/en not_active Expired
- 1982-01-13 GB GB8200896A patent/GB2091052B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| SE8107251L (en) | 1982-07-15 |
| FR2498029B1 (en) | 1985-07-05 |
| DK282A (en) | 1982-07-15 |
| JPS57129172A (en) | 1982-08-11 |
| GB2091052B (en) | 1984-11-28 |
| DE3100821A1 (en) | 1982-08-12 |
| FR2498029A1 (en) | 1982-07-16 |
| GB2091052A (en) | 1982-07-21 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry | ||
| MKEX | Expiry |
Effective date: 20020409 |