Arrangement for monitoring a frequency converter

• US 20060265160A1
• Filed: 05/02/2006
• Published: 11/23/2006
• Est. Priority Date: 05/03/2005
• Status: Active Grant

• Current Assignee: Vacon Oy (Danfoss A/S)
• Original Assignee: Vacon Oyj (Danfoss A/S)
• Inventors: Komulainen, Risto, Pakkala, Janne
• Granted Patent: US 7,688,603 B2
• Time in Patent Office: Days
• US Class Current: 702/75
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 5/458 using semiconductor devices only

Abstract

An arrangement and method for monitoring a frequency converter, said frequency converter being a voltage-controlled PWM frequency converter provided with a control unit (12) and having an uncontrolled or a mains-frequency controlled mains bridge (10) connectable to an alternating-current source (U_L1, U_L2, U_L3), a direct-voltage intermediate circuit and a controlled load bridge (11) for producing a variable-frequency multi-phase output voltage (U_U, U_V, U_W), which direct-voltage intermediate circuit of the frequency converter is provided with a small-capacitance direct-voltage capacitor, the mains bridge (10) being connected to the load bridge (11) directly without a large-capacitance direct-voltage capacitor functioning as an intermediate energy storage, and which arrangement comprises a measuring unit for measuring the direct voltage of the intermediate voltage circuit. In the arrangement, the measuring unit (MEAS123) measures at least one quantity of the intermediate-circuit direct voltage, and the control unit determines on the basis of the aforesaid quantity at least one input voltage value and/or a failure situation of the frequency converter or its load circuit.

Claims

1. A method for monitoring a frequency converter,

said frequency converter being a voltage-controlled PWM frequency converter having an uncontrolled or a mains-frequency controlled mains bridge (10) connectable to an alternating-current source (U_L1, U_L2, U_L3), a direct-voltage intermediate circuit and a controlled load bridge (11) for producing a variable-frequency multi-phase output voltage (U_U, U_V, U_W),

which direct-voltage intermediate circuit of the frequency converter is provided with a small-capacitance direct-voltage capacitor, the mains bridge (10) being connected to the load bridge (11) directly without a large-capacitance direct-voltage capacitor functioning as an intermediate energy storage, and

in which method the direct voltage of the intermediate voltage circuit is measured,

characterized in that the method comprises

measuring at least one quantity of the intermediate-circuit direct voltage, and

determining on the basis of the aforesaid quantity at least one input voltage value and/or a failure situation of the frequency converter or its load circuit.

2. A method according to claim 1, characterized in that the said quantity is the voltage value of the direct-voltage peaks, on the basis of which is determined the voltage of the alternating-current mains supply network.

3. A method according to claim 1, characterized in that the said quantity is the time between peaks of the direct voltage, on the basis of which is determined the frequency of the alternating-current mains supply network.

4. A method according to claim 1, characterized in that the said quantity is the voltage value of the peaks of the direct voltage, on the basis of which is determined the asymmetry of the alternating-current mains supply network.

5. A method according to claim 1, characterized in that the said quantity is the direct-voltage level and the failure situation is a short-circuit situation, which is detected from the direct voltage level falling rapidly down.

6. An arrangement for magnetic reluctance a frequency converter,

said frequency converter being a voltage-controlled PWM frequency converter provided with a control unit (12) and having an uncontrolled or a mains-frequency controlled mains bridge (10) connectable to an alternating-current source (U_L1, U_L2, U_L3), a direct-voltage intermediate circuit and a controlled load bridge (11) for producing a variable-frequency multi-phase output voltage (U_U, U_V, U_W),

which direct-voltage intermediate circuit of the frequency converter is provided with a small-capacitance direct-voltage capacitor, the mains bridge (10) being connected to the load bridge (11) directly without a large-capacitance direct-voltage capacitor functioning as an intermediate energy storage, and

which arrangement comprises a measuring unit for measuring the direct voltage of the intermediate voltage circuit,

characterized in that in the arrangement

the measuring unit (MEAS123) measures at least one quantity of the intermediate-circuit direct voltage, and

the control unit determines on the basis of the aforesaid quantity at least one input voltage value and/or a failure situation of the frequency converter or its load circuit.

7. An arrangement according to claim 6, characterized in that the said quantity is the voltage value of the direct-voltage peaks, on the basis of which is determined the voltage of the alternating-current mains supply network.

8. An arrangement according to claim 6, characterized in that the said quantity is the time between peaks of the direct voltage, on the basis of which is determined the frequency of the alternating-current mains supply network.

9. An arrangement according to claim 6, characterized in that the said quantity is the voltage value of the peaks of the direct voltage, on the basis of which is determined the asymmetry of the alternating-current mains supply network.

10. An arrangement according to claim 6, characterized in that the said quantity is the direct-voltage level and the failure situation is a short-circuit situation, which is detected from the direct voltage level falling rapidly down.

11. Use of direct-voltage measurement of the intermediate voltage circuit of a frequency converter, said frequency converter being a voltage-controlled PWM frequency converter having an uncontrolled or a mains-frequency controlled mains bridge (10) connectable to an alternating-current source (U_L1, U_L2, U_L3), a direct-voltage intermediate circuit and a controlled load bridge (11) for producing a variable-frequency multi-phase output voltage (U_U, U_V, U_W), which direct-voltage intermediate circuit of the frequency converter is provided with a small-capacitance direct-voltage capacitor, the mains bridge (10) being connected to the load bridge (11) directly without a large-capacitance direct-voltage capacitor functioning as an intermediate energy storage,

to determine at least one supply voltage value and/or a failure situation of the frequency converter or its load circuit.